From 324b5143ab017c02a050b15192d8080a4f5aa850 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 30 Jul 2023 21:03:41 -0500
Subject: [PATCH 01/55] OcFileLib: Add OcDiskGetDevicePath function

---
 Include/Acidanthera/Library/OcFileLib.h       | 12 ++++
 .../{GptPartitionEntry.c => DiskMisc.c}       | 71 ++++++++++++-------
 Library/OcFileLib/OcFileLib.inf               |  2 +-
 3 files changed, 58 insertions(+), 27 deletions(-)
 rename Library/OcFileLib/{GptPartitionEntry.c => DiskMisc.c} (96%)

diff --git a/Include/Acidanthera/Library/OcFileLib.h b/Include/Acidanthera/Library/OcFileLib.h
index 8846d6eada6..8eb973dac2e 100644
--- a/Include/Acidanthera/Library/OcFileLib.h
+++ b/Include/Acidanthera/Library/OcFileLib.h
@@ -482,6 +482,18 @@ OcOpenFileByDevicePath (
   IN     UINT64                    Attributes
   );
 
+/**
+  Retrieve the disk's Device Path from a partition's Device Path.
+
+  @param[in] HdDevicePath  The Device Path of the partition.
+
+  @retval Device Path or NULL
+**/
+EFI_DEVICE_PATH_PROTOCOL*
+OcDiskGetDevicePath (
+  IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
+  );
+
 /**
   Retrieve the disk's device handle from a partition's Device Path.
 
diff --git a/Library/OcFileLib/GptPartitionEntry.c b/Library/OcFileLib/DiskMisc.c
similarity index 96%
rename from Library/OcFileLib/GptPartitionEntry.c
rename to Library/OcFileLib/DiskMisc.c
index b0f4b8a02a0..28bfcef35ef 100644
--- a/Library/OcFileLib/GptPartitionEntry.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -173,7 +173,6 @@ STATIC
 EFI_HANDLE
 InternalPartitionGetDiskHandle (
   IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath,
-  IN  UINTN                     HdNodeOffset,
   OUT BOOLEAN                   *HasBlockIo2
   )
 {
@@ -181,27 +180,14 @@ InternalPartitionGetDiskHandle (
 
   EFI_STATUS  Status;
 
-  EFI_DEVICE_PATH_PROTOCOL  *PrefixPath;
+  EFI_DEVICE_PATH_PROTOCOL  *DiskPath;
   EFI_DEVICE_PATH_PROTOCOL  *TempPath;
 
   ASSERT (HdDevicePath != NULL);
-  ASSERT (HdNodeOffset < GetDevicePathSize (HdDevicePath));
   ASSERT (HasBlockIo2 != NULL);
 
-  PrefixPath = DuplicateDevicePath (HdDevicePath);
-  if (PrefixPath == NULL) {
-    DEBUG ((DEBUG_INFO, "OCPI: DP allocation error\n"));
-    return NULL;
-  }
-
-  //
-  // Strip the HD node in order to retrieve the last node supporting Block I/O
-  // before it, which is going to be its disk.
-  //
-  TempPath = (EFI_DEVICE_PATH_PROTOCOL *)((UINTN)PrefixPath + HdNodeOffset);
-  SetDevicePathEndNode (TempPath);
-
-  TempPath = PrefixPath;
+  DiskPath = OcDiskGetDevicePath (HdDevicePath);
+  TempPath = DiskPath;
   Status   = gBS->LocateDevicePath (
                     &gEfiBlockIo2ProtocolGuid,
                     &TempPath,
@@ -210,7 +196,7 @@ InternalPartitionGetDiskHandle (
   *HasBlockIo2 = !EFI_ERROR (Status);
 
   if (EFI_ERROR (Status)) {
-    TempPath = PrefixPath;
+    TempPath = DiskPath;
     Status   = gBS->LocateDevicePath (
                       &gEfiBlockIoProtocolGuid,
                       &TempPath,
@@ -222,30 +208,32 @@ InternalPartitionGetDiskHandle (
     DebugPrintDevicePath (
       DEBUG_INFO,
       "OCPI: Failed to locate disk",
-      PrefixPath
+      TempPath
       );
 
     DiskHandle = NULL;
   }
 
-  FreePool (PrefixPath);
+  FreePool (DiskPath);
 
   return DiskHandle;
 }
 
 /**
-  Retrieve the disk's device handle from a partition's Device Path.
+  Retrieve the disk's Device Path from a partition's Device Path.
 
   @param[in] HdDevicePath  The Device Path of the partition.
 
+  @retval Device Path or NULL
 **/
-EFI_HANDLE
-OcPartitionGetDiskHandle (
+EFI_DEVICE_PATH_PROTOCOL*
+OcDiskGetDevicePath (
   IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   )
 {
+  EFI_DEVICE_PATH_PROTOCOL     *PrefixPath;
+  EFI_DEVICE_PATH_PROTOCOL     *TempPath;
   CONST HARDDRIVE_DEVICE_PATH  *HdNode;
-  BOOLEAN                      Dummy;
 
   ASSERT (HdDevicePath != NULL);
 
@@ -260,9 +248,41 @@ OcPartitionGetDiskHandle (
     return NULL;
   }
 
+  PrefixPath = DuplicateDevicePath (HdDevicePath);
+  if (PrefixPath == NULL) {
+    DEBUG ((DEBUG_INFO, "OCPI: DP allocation error\n"));
+    return NULL;
+  }
+
+  //
+  // Strip the HD node in order to retrieve the last node supporting Block I/O
+  // before it, which is going to be its disk.
+  //
+  TempPath = (EFI_DEVICE_PATH_PROTOCOL *)((UINTN)PrefixPath + ((UINTN)HdNode - (UINTN)HdDevicePath));
+  SetDevicePathEndNode (TempPath);
+
+  TempPath = PrefixPath;
+
+  return TempPath;
+}
+
+/**
+  Retrieve the disk's device handle from a partition's Device Path.
+
+  @param[in] HdDevicePath  The Device Path of the partition.
+
+**/
+EFI_HANDLE
+OcPartitionGetDiskHandle (
+  IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
+  )
+{
+  BOOLEAN                      Dummy;
+
+  ASSERT (HdDevicePath != NULL);
+
   return InternalPartitionGetDiskHandle (
            HdDevicePath,
-           (UINTN)HdNode - (UINTN)HdDevicePath,
            &Dummy
            );
 }
@@ -591,7 +611,6 @@ OcGetGptPartitionEntry (
 
   DiskHandle = InternalPartitionGetDiskHandle (
                  FsDevicePath,
-                 (UINTN)HdNode - (UINTN)FsDevicePath,
                  &HasBlockIo2
                  );
   if (DiskHandle == NULL) {
diff --git a/Library/OcFileLib/OcFileLib.inf b/Library/OcFileLib/OcFileLib.inf
index e81d5a24c5f..d801c25b94f 100755
--- a/Library/OcFileLib/OcFileLib.inf
+++ b/Library/OcFileLib/OcFileLib.inf
@@ -33,7 +33,7 @@
   LocateFileSystem.c
   OpenFile.c
   ReadFile.c
-  GptPartitionEntry.c
+  DiskMisc.c
   FirmwareFile.c
   FileMisc.c
 

From 6a4a475446fdfb2aa7773184dc4d359d1ce299f6 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 30 Jul 2023 21:05:48 -0500
Subject: [PATCH 02/55] OcFileLib: Fix uncrustify on previous commit

---
 Include/Acidanthera/Library/OcFileLib.h | 2 +-
 Library/OcFileLib/DiskMisc.c            | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Include/Acidanthera/Library/OcFileLib.h b/Include/Acidanthera/Library/OcFileLib.h
index 8eb973dac2e..116a587eee3 100644
--- a/Include/Acidanthera/Library/OcFileLib.h
+++ b/Include/Acidanthera/Library/OcFileLib.h
@@ -489,7 +489,7 @@ OcOpenFileByDevicePath (
 
   @retval Device Path or NULL
 **/
-EFI_DEVICE_PATH_PROTOCOL*
+EFI_DEVICE_PATH_PROTOCOL *
 OcDiskGetDevicePath (
   IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   );
diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index 28bfcef35ef..a2acd037499 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -226,7 +226,7 @@ InternalPartitionGetDiskHandle (
 
   @retval Device Path or NULL
 **/
-EFI_DEVICE_PATH_PROTOCOL*
+EFI_DEVICE_PATH_PROTOCOL *
 OcDiskGetDevicePath (
   IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   )
@@ -277,7 +277,7 @@ OcPartitionGetDiskHandle (
   IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   )
 {
-  BOOLEAN                      Dummy;
+  BOOLEAN  Dummy;
 
   ASSERT (HdDevicePath != NULL);
 

From 50b0e45e6fa7b33bf5db07928a37f50f257d895d Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 30 Jul 2023 21:25:19 -0500
Subject: [PATCH 03/55] OcBootManagementLib: Add initial functions for Mac
 legacy booting

---
 .../BootManagementInternal.h                  |  13 +
 .../OcBootManagementLib/LegacyBootSupport.c   | 297 ++++++++++++++++++
 .../OcBootManagementLib.inf                   |   1 +
 3 files changed, 311 insertions(+)
 create mode 100644 Library/OcBootManagementLib/LegacyBootSupport.c

diff --git a/Library/OcBootManagementLib/BootManagementInternal.h b/Library/OcBootManagementLib/BootManagementInternal.h
index 1a3ac19387a..6b16061accb 100644
--- a/Library/OcBootManagementLib/BootManagementInternal.h
+++ b/Library/OcBootManagementLib/BootManagementInternal.h
@@ -124,6 +124,19 @@ typedef enum {
   BootEntryDisabled,
 } INTERNAL_ENTRY_VISIBILITY;
 
+EFI_STATUS
+InternalLoadAppleLegacyInterface (
+  IN  EFI_HANDLE                ParentImageHandle,
+  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath,
+  OUT EFI_HANDLE                *ImageHandle
+  );
+
+BOOLEAN
+InternalDiskContainsBootcode (
+  IN EFI_HANDLE  DiskHandle,
+  IN BOOLEAN     UseBlockIo2
+  );
+
 EFI_STATUS
 InternalCheckScanPolicy (
   IN  EFI_HANDLE  Handle,
diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
new file mode 100644
index 00000000000..45cf0ce3284
--- /dev/null
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -0,0 +1,297 @@
+/** @file
+  Copyright (C) 2023, Goldfish64. All rights reserved.
+
+  All rights reserved.
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+**/
+
+#include "BootManagementInternal.h"
+
+#include <Protocol/DevicePath.h>
+
+#include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/OcDebugLogLib.h>
+#include <Library/OcDevicePathLib.h>
+#include <Library/OcFileLib.h>
+#include <Library/OcMiscLib.h>
+#include <Library/PrintLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+
+#define MBR_SECTOR_SIZE  512
+
+//
+// PIWG firmware media device path for Apple legacy interface.
+// FwFile(2B0585EB-D8B8-49A9-8B8CE21B01AEF2B7)
+//
+static CONST UINT8                     AppleLegacyInterfaceMediaDevicePathData[] = {
+  0x04, 0x06, 0x14, 0x00, 0xEB, 0x85, 0x05, 0x2B,
+  0xB8, 0xD8, 0xA9, 0x49, 0x8B, 0x8C, 0xE2, 0x1B,
+  0x01, 0xAE, 0xF2, 0xB7, 0x7F, 0xFF, 0x04, 0x00,
+};
+static CONST EFI_DEVICE_PATH_PROTOCOL  *AppleLegacyInterfaceMediaDevicePathPath = (EFI_DEVICE_PATH_PROTOCOL *)AppleLegacyInterfaceMediaDevicePathData;
+
+#define MAX_APPLE_LEGACY_DEVICE_PATHS  16
+
+STATIC
+BOOLEAN
+CheckLegacySignature (
+  IN CONST CHAR8  *SignatureStr,
+  IN UINT8        *Buffer,
+  IN UINTN        BufferSize
+  )
+{
+  UINT32  Offset;
+
+  Offset = 0;
+
+  return FindPattern ((CONST UINT8 *)SignatureStr, NULL, AsciiStrLen (SignatureStr), Buffer, BufferSize, &Offset);
+}
+
+STATIC
+EFI_STATUS
+ScanAppleLegacyInterfacePaths (
+  IN OUT EFI_DEVICE_PATH_PROTOCOL  **DevicePaths,
+  IN     UINTN                     MaxDevicePaths
+  )
+{
+  EFI_STATUS  Status;
+  UINTN       NoHandles;
+  EFI_HANDLE  *Handles;
+  UINTN       HandleIndex;
+  UINTN       PathCount;
+  UINTN       PathIndex;
+  BOOLEAN     DevicePathExists;
+
+  EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
+  EFI_DEVICE_PATH_PROTOCOL   *DevicePath;
+
+  MaxDevicePaths--;
+  PathCount = 0;
+
+  //
+  // Get all LoadedImage protocol handles.
+  //
+  Status = gBS->LocateHandleBuffer (
+                  ByProtocol,
+                  &gEfiLoadedImageProtocolGuid,
+                  NULL,
+                  &NoHandles,
+                  &Handles
+                  );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  for (HandleIndex = 0; HandleIndex < NoHandles && PathCount < MaxDevicePaths; HandleIndex++) {
+    Status = gBS->HandleProtocol (
+                    Handles[HandleIndex],
+                    &gEfiLoadedImageProtocolGuid,
+                    (VOID **)&LoadedImage
+                    );
+    if (EFI_ERROR (Status)) {
+      continue;
+    }
+
+    Status = gBS->HandleProtocol (
+                    LoadedImage->DeviceHandle,
+                    &gEfiDevicePathProtocolGuid,
+                    (VOID **)&DevicePath
+                    );
+    if (EFI_ERROR (Status)) {
+      continue;
+    }
+
+    //
+    // Legacy boot interface will be behind a memory range node.
+    //
+    if (  (DevicePathType (DevicePath) != HARDWARE_DEVICE_PATH)
+       || (DevicePathSubType (DevicePath) != HW_MEMMAP_DP))
+    {
+      continue;
+    }
+
+    //
+    // Ensure we don't add a duplicate path.
+    //
+    DevicePathExists = FALSE;
+    for (PathIndex = 0; PathIndex < PathCount; PathIndex++) {
+      if (DevicePathNodeLength (DevicePath) != DevicePathNodeLength (DevicePaths[PathIndex])) {
+        continue;
+      }
+
+      if (CompareMem (DevicePath, DevicePaths[PathIndex], DevicePathNodeLength (DevicePath))) {
+        DevicePathExists = TRUE;
+        break;
+      }
+    }
+
+    if (DevicePathExists) {
+      continue;
+    }
+
+    DevicePaths[PathCount++] = AppendDevicePath (DevicePath, AppleLegacyInterfaceMediaDevicePathPath);
+  }
+
+  FreePool (Handles);
+
+  DevicePaths[PathCount] = NULL;
+  return EFI_SUCCESS;
+}
+
+EFI_STATUS
+InternalLoadAppleLegacyInterface (
+  IN  EFI_HANDLE                ParentImageHandle,
+  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath,
+  OUT EFI_HANDLE                *ImageHandle
+  )
+{
+  EFI_STATUS                Status;
+  EFI_DEVICE_PATH_PROTOCOL  *WholeDiskPath;
+  EFI_DEVICE_PATH_PROTOCOL  **LegacyDevicePaths;
+  CHAR16                    *UnicodeDevicePath;
+  UINTN                     Index;
+
+  //
+  // Get device path to disk to be booted.
+  // TODO: Handle CD booting, device path is not required in that case.
+  //
+  WholeDiskPath = OcDiskGetDevicePath (HdDevicePath);
+  if (WholeDiskPath == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  DebugPrintDevicePath (DEBUG_INFO, "OCB: Legacy disk device path", WholeDiskPath);
+
+  // TODO: Mark target partition as active on pure MBR and hybrid GPT disks.
+  // Macs only boot the active partition.
+
+  //
+  // Set BootCampHD variable pointing to target disk.
+  //
+  Status = gRT->SetVariable (
+                  APPLE_BOOT_CAMP_HD_VARIABLE_NAME,
+                  &gAppleBootVariableGuid,
+                  EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
+                  GetDevicePathSize (WholeDiskPath),
+                  WholeDiskPath
+                  );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // Get list of possible locations for Apple legacy interface and attempt to load.
+  //
+  LegacyDevicePaths = AllocateZeroPool (sizeof (*LegacyDevicePaths) * MAX_APPLE_LEGACY_DEVICE_PATHS);
+  if (LegacyDevicePaths == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  Status = ScanAppleLegacyInterfacePaths (LegacyDevicePaths, MAX_APPLE_LEGACY_DEVICE_PATHS);
+  if (!EFI_ERROR (Status)) {
+    for (Index = 0; LegacyDevicePaths[Index] != NULL; Index++) {
+      Status = gBS->LoadImage (
+                      FALSE,
+                      ParentImageHandle,
+                      LegacyDevicePaths[Index],
+                      NULL,
+                      0,
+                      ImageHandle
+                      );
+      if (Status != EFI_NOT_FOUND) {
+        DEBUG_CODE_BEGIN ();
+
+        UnicodeDevicePath = ConvertDevicePathToText (LegacyDevicePaths[Index], FALSE, FALSE);
+        DEBUG ((
+          DEBUG_INFO,
+          "OCB: Loaded Apple legacy interface at dp %s - %r\n",
+          UnicodeDevicePath != NULL ? UnicodeDevicePath : L"<null>",
+          Status
+          ));
+        if (UnicodeDevicePath != NULL) {
+          FreePool (UnicodeDevicePath);
+        }
+
+        DEBUG_CODE_END ();
+
+        break;
+      }
+    }
+  }
+
+  FreePool (LegacyDevicePaths);
+
+  return Status;
+}
+
+BOOLEAN
+InternalDiskContainsBootcode (
+  IN EFI_HANDLE  DiskHandle,
+  IN BOOLEAN     UseBlockIo2
+  )
+{
+  EFI_STATUS  Status;
+  UINT8       *Buffer;
+  UINTN       BufferSize;
+  BOOLEAN     BootcodeResult;
+
+  OC_DISK_CONTEXT  DiskContext;
+
+  ASSERT (DiskHandle != NULL);
+
+  Status = OcDiskInitializeContext (&DiskContext, DiskHandle, UseBlockIo2);
+  if (EFI_ERROR (Status)) {
+    return FALSE;
+  }
+
+  //
+  // Retrieve the first sector of the disk.
+  //
+  BufferSize = ALIGN_VALUE (MBR_SECTOR_SIZE, DiskContext.BlockSize);
+  Buffer     = AllocatePool (BufferSize);
+  if (Buffer == NULL) {
+    DEBUG ((DEBUG_INFO, "OCBP: Buffer allocation error\n"));
+    return FALSE;
+  }
+
+  Status = OcDiskRead (
+             &DiskContext,
+             0,
+             BufferSize,
+             Buffer
+             );
+
+  if (EFI_ERROR (Status)) {
+    FreePool (Buffer);
+    return FALSE;
+  }
+
+  //
+  // Validate sector contents and check for known signatures
+  // indicating the partition is bootable.
+  //
+  BootcodeResult = FALSE;
+  if (CheckLegacySignature ("BOOTMGR", Buffer, BufferSize)) {
+    DEBUG ((DEBUG_INFO, "OCB: Found Windows BOOTMGR\n"));
+    BootcodeResult = TRUE;
+  } else if (CheckLegacySignature ("NTLDR", Buffer, BufferSize)) {
+    DEBUG ((DEBUG_INFO, "OCB: Found Windows NTLDR\n"));
+    BootcodeResult = TRUE;
+  }
+
+  FreePool (Buffer);
+
+  return BootcodeResult;
+}
diff --git a/Library/OcBootManagementLib/OcBootManagementLib.inf b/Library/OcBootManagementLib/OcBootManagementLib.inf
index efb5743b9a3..02b44687c72 100644
--- a/Library/OcBootManagementLib/OcBootManagementLib.inf
+++ b/Library/OcBootManagementLib/OcBootManagementLib.inf
@@ -45,6 +45,7 @@
   DmgBootSupport.c
   HotKeySupport.c
   ImageLoader.c
+  LegacyBootSupport.c
   PolicyManagement.c
   OcBootManagementLib.c
 

From 86717d44c8c716dddd4e9722a9f78f4140062d5b Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 30 Jul 2023 21:44:08 -0500
Subject: [PATCH 04/55] OcBootManagementLib: Fix Windows build error

---
 Library/OcBootManagementLib/LegacyBootSupport.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index 45cf0ce3284..3e9f9cdddac 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -49,7 +49,7 @@ BOOLEAN
 CheckLegacySignature (
   IN CONST CHAR8  *SignatureStr,
   IN UINT8        *Buffer,
-  IN UINTN        BufferSize
+  IN UINT32       BufferSize
   )
 {
   UINT32  Offset;
@@ -244,7 +244,7 @@ InternalDiskContainsBootcode (
 {
   EFI_STATUS  Status;
   UINT8       *Buffer;
-  UINTN       BufferSize;
+  UINT32      BufferSize;
   BOOLEAN     BootcodeResult;
 
   OC_DISK_CONTEXT  DiskContext;

From 5a5112059c092254924fd2c2a7f4c00644b15d4a Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 30 Jul 2023 22:06:33 -0500
Subject: [PATCH 05/55] OcBootManagementLib: Fix Windows build error

---
 Library/OcBootManagementLib/LegacyBootSupport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index 3e9f9cdddac..79360e37a38 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -56,7 +56,7 @@ CheckLegacySignature (
 
   Offset = 0;
 
-  return FindPattern ((CONST UINT8 *)SignatureStr, NULL, AsciiStrLen (SignatureStr), Buffer, BufferSize, &Offset);
+  return FindPattern ((CONST UINT8 *)SignatureStr, NULL, (CONST UINT32) AsciiStrLen (SignatureStr), Buffer, BufferSize, &Offset);
 }
 
 STATIC

From 9893ce7ad0f392bbe821a11138ec2032c8ca83d9 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 31 Jul 2023 18:33:39 -0500
Subject: [PATCH 06/55] OcBootManagementLib: Add legacy boot entry detection

---
 .../Acidanthera/Library/OcBootManagementLib.h |  30 +++
 Library/OcBootManagementLib/BootEntryInfo.c   |  26 +++
 .../OcBootManagementLib/BootEntryManagement.c | 200 +++++++++++++++---
 .../BootManagementInternal.h                  |  25 ++-
 .../OcBootManagementLib/DefaultEntryChoice.c  |  24 ++-
 .../OcBootManagementLib/LegacyBootSupport.c   |  34 ++-
 .../OcBootManagementLib/PolicyManagement.c    |   3 +-
 Library/OcMainLib/OpenCoreMisc.c              |   8 +
 8 files changed, 288 insertions(+), 62 deletions(-)

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index 6c91c350102..934dd6095fe 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -153,6 +153,23 @@ typedef UINT32 OC_BOOT_ENTRY_TYPE;
 #define OC_BOOT_EXTERNAL_TOOL       BIT7
 #define OC_BOOT_SYSTEM              BIT8
 
+/**
+  Legacy system boot type.
+**/
+typedef enum OC_LEGACY_BOOT_TYPE_ {
+  OcLegacyBootTypeNone,
+  OcLegacyBootTypeApple
+} OC_LEGACY_BOOT_TYPE;
+
+/**
+  Legacy operating system type.
+**/
+typedef enum OC_LEGACY_OS_TYPE_ {
+  OcLegacyOsTypeNone,
+  OcLegacyOsTypeWindowsNtldr,
+  OcLegacyOsTypeWindowsBootmgr
+} OC_LEGACY_OS_TYPE;
+
 /**
   Picker mode.
 **/
@@ -262,6 +279,11 @@ typedef struct OC_BOOT_ENTRY_ {
   //
   BOOLEAN                     IsAppleInstaller;
   //
+  // Describes type of legacy OS to be booted.
+  // Set when entry is to be booted through legacy interface.
+  //
+  OC_LEGACY_OS_TYPE           LegacyOsType;
+  //
   // Should make this option default boot option.
   //
   BOOLEAN                     SetDefault;
@@ -348,6 +370,10 @@ struct OC_BOOT_FILESYSTEM_ {
   //
   BOOLEAN               LoaderFs;
   //
+  // Legacy bootsector type.
+  //
+  OC_LEGACY_OS_TYPE     LegacyOsType;
+  //
   // Contains recovery on the filesystem.
   //
   BOOLEAN               HasSelfRecovery;
@@ -949,6 +975,10 @@ struct OC_PICKER_CONTEXT_ {
   //
   CONST CHAR8                 *InstanceIdentifier;
   //
+  // Legacy boot method type.
+  //
+  OC_LEGACY_BOOT_TYPE         LegacyBootType;
+  //
   // Enable polling boot arguments.
   //
   BOOLEAN                     PollAppleHotKeys;
diff --git a/Library/OcBootManagementLib/BootEntryInfo.c b/Library/OcBootManagementLib/BootEntryInfo.c
index b150ea334bb..4171e8d94a5 100644
--- a/Library/OcBootManagementLib/BootEntryInfo.c
+++ b/Library/OcBootManagementLib/BootEntryInfo.c
@@ -890,3 +890,29 @@ InternalDescribeBootEntry (
 
   return EFI_SUCCESS;
 }
+
+EFI_STATUS
+InternalDescribeLegacyBootEntry (
+  IN     OC_BOOT_CONTEXT    *BootContext,
+  IN     OC_LEGACY_OS_TYPE  LegacyOsType,
+  IN OUT OC_BOOT_ENTRY      *BootEntry
+  )
+{
+  ASSERT (LegacyOsType != OcLegacyOsTypeNone);
+
+  //
+  // Name is based on previously detected boot sector type.
+  //
+  switch (LegacyOsType) {
+    case OcLegacyOsTypeWindowsBootmgr:
+    case OcLegacyOsTypeWindowsNtldr:
+      BootEntry->Type = OC_BOOT_WINDOWS;
+      BootEntry->Name = AllocateCopyPool (sizeof (L"Windows (legacy)"), L"Windows (legacy)");
+      break;
+
+    default:
+      break;
+  }
+
+  return EFI_SUCCESS;
+}
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 5ccdb05dc0a..24eddbeb0a5 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -1595,6 +1595,92 @@ AddBootEntryFromBootOption (
   return Status;
 }
 
+/**
+  Create bootable entries from legacy boot partitons.
+
+  @param[in,out] BootContext   Context of filesystems.
+  @param[in,out] FileSystem    Filesystem to scan for recovery.
+
+  @retval EFI_SUCCESS on success.
+**/
+STATIC
+EFI_STATUS
+AddBootEntryFromLegacyPartition (
+  IN OUT OC_BOOT_CONTEXT     *BootContext,
+  IN OUT OC_BOOT_FILESYSTEM  *FileSystem
+  )
+{
+  EFI_STATUS                Status;
+  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
+  OC_BOOT_ENTRY             *BootEntry;
+
+  //
+  // Only support legacy filesystems.
+  //
+  if (FileSystem->LegacyOsType == OcLegacyOsTypeNone) {
+    return EFI_UNSUPPORTED;
+  }
+
+  Status = gBS->HandleProtocol (
+                  FileSystem->Handle,
+                  &gEfiDevicePathProtocolGuid,
+                  (VOID **)&DevicePath
+                  );
+  if (EFI_ERROR (Status)) {
+    return EFI_UNSUPPORTED;
+  }
+
+  DebugPrintDevicePath (DEBUG_INFO, "OCB: Adding legacy entry for disk", DevicePath);
+
+  //
+  // Allocate, initialise, and describe boot entry.
+  //
+  BootEntry = AllocateZeroPool (sizeof (*BootEntry));
+  if (BootEntry == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  BootEntry->IsExternal   = FileSystem->External;
+  BootEntry->DevicePath   = DevicePath;
+  BootEntry->LegacyOsType = FileSystem->LegacyOsType;
+  BootEntry->LaunchInText = TRUE;
+
+  //
+  // Load options are set based on type of disk.
+  // Internal disk = "HD"
+  // External disk = "USB"
+  // Optical disk  = "CD"
+  //
+  // TODO: Support optical media.
+  //
+  if (BootEntry->IsExternal) {
+    BootEntry->LoadOptionsSize = L_STR_SIZE ("USB");
+    BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("USB"), "USB");
+  } else {
+    BootEntry->LoadOptionsSize = L_STR_SIZE ("HD");
+    BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
+  }
+
+  if (BootEntry->LoadOptions == NULL) {
+    FreePool (BootEntry);
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  Status = InternalDescribeLegacyBootEntry (BootContext, FileSystem->LegacyOsType, BootEntry);
+  if (EFI_ERROR (Status)) {
+    FreePool (BootEntry);
+    return Status;
+  }
+
+  RegisterBootOption (
+    BootContext,
+    FileSystem,
+    BootEntry
+    );
+
+  return EFI_SUCCESS;
+}
+
 /**
   Allocate a new filesystem entry in boot entries
   in case it can be used according to current ScanPolicy.
@@ -1608,9 +1694,10 @@ AddBootEntryFromBootOption (
 STATIC
 EFI_STATUS
 AddFileSystemEntry (
-  IN OUT OC_BOOT_CONTEXT  *BootContext,
-  IN     EFI_HANDLE       FileSystemHandle,
-  OUT OC_BOOT_FILESYSTEM  **FileSystemEntry  OPTIONAL
+  IN OUT OC_BOOT_CONTEXT    *BootContext,
+  IN     EFI_HANDLE         FileSystemHandle,
+  IN     OC_LEGACY_OS_TYPE  LegacyOsType,
+  OUT OC_BOOT_FILESYSTEM    **FileSystemEntry  OPTIONAL
   )
 {
   EFI_STATUS                Status;
@@ -1624,6 +1711,7 @@ AddFileSystemEntry (
   Status = InternalCheckScanPolicy (
              FileSystemHandle,
              BootContext->PickerContext->ScanPolicy,
+             LegacyOsType != OcLegacyOsTypeNone,
              &IsExternal
              );
 
@@ -1644,10 +1732,11 @@ AddFileSystemEntry (
 
   DEBUG ((
     DEBUG_INFO,
-    "OCB: Adding fs %p (E:%d|L:%d|P:%r) - %s\n",
+    "OCB: Adding fs %p (E:%d|L:%d|B:%d|P:%r) - %s\n",
     FileSystemHandle,
     IsExternal,
     LoaderFs,
+    LegacyOsType,
     Status,
     OC_HUMAN_STRING (TextDevicePath)
     ));
@@ -1672,6 +1761,7 @@ AddFileSystemEntry (
   Entry->RecoveryFs      = NULL;
   Entry->External        = IsExternal;
   Entry->LoaderFs        = LoaderFs;
+  Entry->LegacyOsType    = LegacyOsType;
   Entry->HasSelfRecovery = FALSE;
   InsertTailList (&BootContext->FileSystems, &Entry->Link);
   ++BootContext->FileSystemCount;
@@ -1815,7 +1905,7 @@ InternalFileSystemForHandle (
     return NULL;
   }
 
-  Status = AddFileSystemEntry (BootContext, FileSystemHandle, &FileSystem);
+  Status = AddFileSystemEntry (BootContext, FileSystemHandle, FALSE, &FileSystem);
   if (!EFI_ERROR (Status)) {
     return FileSystem;
   }
@@ -1830,11 +1920,12 @@ BuildFileSystemList (
   IN BOOLEAN            Empty
   )
 {
-  OC_BOOT_CONTEXT  *BootContext;
-  EFI_STATUS       Status;
-  UINTN            NoHandles;
-  EFI_HANDLE       *Handles;
-  UINTN            Index;
+  OC_BOOT_CONTEXT    *BootContext;
+  EFI_STATUS         Status;
+  OC_LEGACY_OS_TYPE  LegacyOsType;
+  UINTN              NoHandles;
+  EFI_HANDLE         *Handles;
+  UINTN              Index;
 
   BootContext = AllocatePool (sizeof (*BootContext));
   if (BootContext == NULL) {
@@ -1857,6 +1948,9 @@ BuildFileSystemList (
     return BootContext;
   }
 
+  //
+  // Add readable filesystems.
+  //
   Status = gBS->LocateHandleBuffer (
                   ByProtocol,
                   &gEfiSimpleFileSystemProtocolGuid,
@@ -1872,11 +1966,43 @@ BuildFileSystemList (
     AddFileSystemEntry (
       BootContext,
       Handles[Index],
+      FALSE,
       NULL
       );
   }
 
   FreePool (Handles);
+
+  //
+  // Add legacy partitions with valid boot sectors if on a supported legacy platform.
+  //
+  if (Context->LegacyBootType != OcLegacyBootTypeNone) {
+    Status = gBS->LocateHandleBuffer (
+                    ByProtocol,
+                    &gEfiBlockIoProtocolGuid,
+                    NULL,
+                    &NoHandles,
+                    &Handles
+                    );
+    if (EFI_ERROR (Status)) {
+      return BootContext;
+    }
+
+    for (Index = 0; Index < NoHandles; ++Index) {
+      LegacyOsType = InternalGetDiskLegacyOsType (Handles[Index], FALSE);
+      if (LegacyOsType == OcLegacyOsTypeNone) {
+        continue;
+      }
+
+      AddFileSystemEntry (
+        BootContext,
+        Handles[Index],
+        LegacyOsType,
+        NULL
+        );
+    }
+  }
+
   return BootContext;
 }
 
@@ -2079,28 +2205,40 @@ OcScanForBootEntries (
   {
     FileSystem = BASE_CR (Link, OC_BOOT_FILESYSTEM, Link);
 
-    PartitionEntry                  = OcGetGptPartitionEntry (FileSystem->Handle);
-    IsDefaultEntryProtocolPartition = (
-                                         (DefaultEntryId != NULL)
-                                      && CompareGuid (
-                                           &DefaultEntryPartuuid,
-                                           (PartitionEntry == NULL) ? &gEfiPartTypeUnusedGuid : &PartitionEntry->UniquePartitionGUID
-                                           )
-                                         );
+    if (FileSystem->LegacyOsType != OcLegacyOsTypeNone) {
+      //
+      // Process legacy boot partition.
+      //
+      if (IsListEmpty (&FileSystem->BootEntries)) {
+        AddBootEntryFromLegacyPartition (
+          BootContext,
+          FileSystem
+          );
+      }
+    } else {
+      PartitionEntry                  = OcGetGptPartitionEntry (FileSystem->Handle);
+      IsDefaultEntryProtocolPartition = (
+                                           (DefaultEntryId != NULL)
+                                        && CompareGuid (
+                                             &DefaultEntryPartuuid,
+                                             (PartitionEntry == NULL) ? &gEfiPartTypeUnusedGuid : &PartitionEntry->UniquePartitionGUID
+                                             )
+                                           );
 
-    //
-    // No entries, or only entry pre-created from boot entry protocol,
-    // so process this directory with Apple Bless.
-    //
-    if (IsDefaultEntryProtocolPartition || IsListEmpty (&FileSystem->BootEntries)) {
-      AddBootEntryFromBless (
-        BootContext,
-        FileSystem,
-        gAppleBootPolicyPredefinedPaths,
-        gAppleBootPolicyNumPredefinedPaths,
-        FALSE,
-        FALSE
-        );
+      //
+      // No entries, or only entry pre-created from boot entry protocol,
+      // so process this directory with Apple Bless.
+      //
+      if (IsDefaultEntryProtocolPartition || IsListEmpty (&FileSystem->BootEntries)) {
+        AddBootEntryFromBless (
+          BootContext,
+          FileSystem,
+          gAppleBootPolicyPredefinedPaths,
+          gAppleBootPolicyNumPredefinedPaths,
+          FALSE,
+          FALSE
+          );
+      }
     }
 
     //
diff --git a/Library/OcBootManagementLib/BootManagementInternal.h b/Library/OcBootManagementLib/BootManagementInternal.h
index 6b16061accb..e40f34b39d2 100644
--- a/Library/OcBootManagementLib/BootManagementInternal.h
+++ b/Library/OcBootManagementLib/BootManagementInternal.h
@@ -131,16 +131,17 @@ InternalLoadAppleLegacyInterface (
   OUT EFI_HANDLE                *ImageHandle
   );
 
-BOOLEAN
-InternalDiskContainsBootcode (
-  IN EFI_HANDLE  DiskHandle,
-  IN BOOLEAN     UseBlockIo2
+OC_LEGACY_OS_TYPE
+InternalGetDiskLegacyOsType (
+  IN  EFI_HANDLE  DiskHandle,
+  IN  BOOLEAN     UseBlockIo2
   );
 
 EFI_STATUS
 InternalCheckScanPolicy (
   IN  EFI_HANDLE  Handle,
   IN  UINT32      Policy,
+  IN  BOOLEAN     Legacy,
   OUT BOOLEAN     *External OPTIONAL
   );
 
@@ -246,6 +247,22 @@ InternalDescribeBootEntry (
   IN OUT OC_BOOT_ENTRY    *BootEntry
   );
 
+/**
+  Describe legacy boot entry contents by setting fields other than DevicePath.
+
+  @param[in]      BootContext   Boot context.
+  @param[in]      LegacyOsType  Legacy OS type.
+  @param[in,out]  BootEntry     Located boot entry.
+
+  @retval EFI_SUCCESS   The entry point is described successfully.
+**/
+EFI_STATUS
+InternalDescribeLegacyBootEntry (
+  IN     OC_BOOT_CONTEXT    *BootContext,
+  IN     OC_LEGACY_OS_TYPE  LegacyOsType,
+  IN OUT OC_BOOT_ENTRY      *BootEntry
+  );
+
 BOOLEAN
 InternalIsAppleLegacyLoadApp (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
diff --git a/Library/OcBootManagementLib/DefaultEntryChoice.c b/Library/OcBootManagementLib/DefaultEntryChoice.c
index 5c118fc072f..cfcb851cc72 100644
--- a/Library/OcBootManagementLib/DefaultEntryChoice.c
+++ b/Library/OcBootManagementLib/DefaultEntryChoice.c
@@ -1577,14 +1577,22 @@ InternalLoadBootEntry (
 
   DEBUG_CODE_END ();
 
-  Status = gBS->LoadImage (
-                  FALSE,
-                  ParentHandle,
-                  DevicePath,
-                  EntryData,
-                  EntryDataSize,
-                  EntryHandle
-                  );
+  if (BootEntry->LegacyOsType != OcLegacyOsTypeNone) {
+    Status = InternalLoadAppleLegacyInterface (
+               ParentHandle,
+               DevicePath,
+               EntryHandle
+               );
+  } else {
+    Status = gBS->LoadImage (
+                    FALSE,
+                    ParentHandle,
+                    DevicePath,
+                    EntryData,
+                    EntryDataSize,
+                    EntryHandle
+                    );
+  }
 
   if (EntryData != NULL) {
     FreePool (EntryData);
diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index 79360e37a38..9a81fe3096f 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -56,7 +56,7 @@ CheckLegacySignature (
 
   Offset = 0;
 
-  return FindPattern ((CONST UINT8 *)SignatureStr, NULL, (CONST UINT32) AsciiStrLen (SignatureStr), Buffer, BufferSize, &Offset);
+  return FindPattern ((CONST UINT8 *)SignatureStr, NULL, (CONST UINT32)AsciiStrLen (SignatureStr), Buffer, BufferSize, &Offset);
 }
 
 STATIC
@@ -236,16 +236,16 @@ InternalLoadAppleLegacyInterface (
   return Status;
 }
 
-BOOLEAN
-InternalDiskContainsBootcode (
-  IN EFI_HANDLE  DiskHandle,
-  IN BOOLEAN     UseBlockIo2
+OC_LEGACY_OS_TYPE
+InternalGetDiskLegacyOsType (
+  IN  EFI_HANDLE  DiskHandle,
+  IN  BOOLEAN     UseBlockIo2
   )
 {
-  EFI_STATUS  Status;
-  UINT8       *Buffer;
-  UINT32      BufferSize;
-  BOOLEAN     BootcodeResult;
+  EFI_STATUS         Status;
+  UINT8              *Buffer;
+  UINT32             BufferSize;
+  OC_LEGACY_OS_TYPE  LegacyOsType;
 
   OC_DISK_CONTEXT  DiskContext;
 
@@ -253,7 +253,7 @@ InternalDiskContainsBootcode (
 
   Status = OcDiskInitializeContext (&DiskContext, DiskHandle, UseBlockIo2);
   if (EFI_ERROR (Status)) {
-    return FALSE;
+    return OcLegacyOsTypeNone;
   }
 
   //
@@ -263,7 +263,7 @@ InternalDiskContainsBootcode (
   Buffer     = AllocatePool (BufferSize);
   if (Buffer == NULL) {
     DEBUG ((DEBUG_INFO, "OCBP: Buffer allocation error\n"));
-    return FALSE;
+    return OcLegacyOsTypeNone;
   }
 
   Status = OcDiskRead (
@@ -275,23 +275,21 @@ InternalDiskContainsBootcode (
 
   if (EFI_ERROR (Status)) {
     FreePool (Buffer);
-    return FALSE;
+    return OcLegacyOsTypeNone;
   }
 
   //
   // Validate sector contents and check for known signatures
   // indicating the partition is bootable.
   //
-  BootcodeResult = FALSE;
+  LegacyOsType = OcLegacyOsTypeNone;
   if (CheckLegacySignature ("BOOTMGR", Buffer, BufferSize)) {
-    DEBUG ((DEBUG_INFO, "OCB: Found Windows BOOTMGR\n"));
-    BootcodeResult = TRUE;
+    LegacyOsType = OcLegacyOsTypeWindowsBootmgr;
   } else if (CheckLegacySignature ("NTLDR", Buffer, BufferSize)) {
-    DEBUG ((DEBUG_INFO, "OCB: Found Windows NTLDR\n"));
-    BootcodeResult = TRUE;
+    LegacyOsType = OcLegacyOsTypeWindowsNtldr;
   }
 
   FreePool (Buffer);
 
-  return BootcodeResult;
+  return LegacyOsType;
 }
diff --git a/Library/OcBootManagementLib/PolicyManagement.c b/Library/OcBootManagementLib/PolicyManagement.c
index f1b52a05910..5fe66fea4ca 100644
--- a/Library/OcBootManagementLib/PolicyManagement.c
+++ b/Library/OcBootManagementLib/PolicyManagement.c
@@ -286,6 +286,7 @@ EFI_STATUS
 InternalCheckScanPolicy (
   IN  EFI_HANDLE  Handle,
   IN  UINT32      Policy,
+  IN  BOOLEAN     Legacy,
   OUT BOOLEAN     *External OPTIONAL
   )
 {
@@ -301,7 +302,7 @@ InternalCheckScanPolicy (
     return EFI_SECURITY_VIOLATION;
   }
 
-  if ((Policy & OC_SCAN_FILE_SYSTEM_LOCK) != 0) {
+  if (!Legacy && ((Policy & OC_SCAN_FILE_SYSTEM_LOCK) != 0)) {
     FileSystemPolicy = OcGetFileSystemPolicyType (Handle);
 
     if ((Policy & FileSystemPolicy) == 0) {
diff --git a/Library/OcMainLib/OpenCoreMisc.c b/Library/OcMainLib/OpenCoreMisc.c
index 29fb6229e67..b2277b58385 100644
--- a/Library/OcMainLib/OpenCoreMisc.c
+++ b/Library/OcMainLib/OpenCoreMisc.c
@@ -939,6 +939,14 @@ OcMiscBoot (
   Context->InstanceIdentifier   = AsciiInstanceIdentifier;
   Context->BlacklistAppleUpdate = Config->Misc.Security.BlacklistAppleUpdate;
 
+  //
+  // Apple legacy boot interface is only available on Apple platforms.
+  //
+  Context->LegacyBootType = OcLegacyBootTypeNone;
+  if (OcStriCmp (L"Apple", gST->FirmwareVendor) == 0) {
+    Context->LegacyBootType = OcLegacyBootTypeApple;
+  }
+
   if ((Config->Misc.Security.ExposeSensitiveData & OCS_EXPOSE_VERSION_UI) != 0) {
     Context->TitleSuffix = OcMiscGetVersionString ();
   }

From 8cd00866253b90b4d6260d34e4d618f4986bf45d Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Tue, 1 Aug 2023 20:39:34 -0500
Subject: [PATCH 07/55] OcBootManagementLib: Fix incorrect device path
 allocation

---
 Library/OcBootManagementLib/BootEntryManagement.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 24eddbeb0a5..999cc037d1c 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -1640,8 +1640,13 @@ AddBootEntryFromLegacyPartition (
     return EFI_OUT_OF_RESOURCES;
   }
 
+  BootEntry->DevicePath = DuplicateDevicePath (DevicePath);
+  if (BootEntry->DevicePath == NULL) {
+    FreePool (BootEntry);
+    return EFI_OUT_OF_RESOURCES;
+  }
+
   BootEntry->IsExternal   = FileSystem->External;
-  BootEntry->DevicePath   = DevicePath;
   BootEntry->LegacyOsType = FileSystem->LegacyOsType;
   BootEntry->LaunchInText = TRUE;
 
@@ -2001,6 +2006,8 @@ BuildFileSystemList (
         NULL
         );
     }
+
+    FreePool (Handles);
   }
 
   return BootContext;

From 44fb3acb3d8b8967ab28eb133e66726ab17fae24 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 5 Aug 2023 12:16:06 -0500
Subject: [PATCH 08/55] OcBootManagementLib: Improve MBR detection

---
 Include/Acidanthera/Library/OcFileLib.h       | 16 ++++
 .../OcBootManagementLib/BootEntryManagement.c |  2 +-
 .../BootManagementInternal.h                  |  5 +-
 .../OcBootManagementLib/LegacyBootSupport.c   | 84 +++++++++++++------
 Library/OcFileLib/DiskMisc.c                  | 67 +++++++++++++++
 5 files changed, 145 insertions(+), 29 deletions(-)

diff --git a/Include/Acidanthera/Library/OcFileLib.h b/Include/Acidanthera/Library/OcFileLib.h
index 116a587eee3..2b923781be1 100644
--- a/Include/Acidanthera/Library/OcFileLib.h
+++ b/Include/Acidanthera/Library/OcFileLib.h
@@ -19,6 +19,8 @@
 
 #include <Guid/FileInfo.h>
 
+#include <IndustryStandard/Mbr.h>
+
 #include <Protocol/SimpleFileSystem.h>
 #include <Protocol/DevicePath.h>
 #include <Protocol/BlockIo.h>
@@ -602,6 +604,20 @@ OcGetGptPartitionEntry (
   IN EFI_HANDLE  FsHandle
   );
 
+/**
+  Retrieve the disk MBR table, if applicable.
+
+  @param[in]  DiskHandle   Disk device handle to retrive MBR partition table from.
+  @param[in]  UseBlockIo2  Use 2nd revision of Block I/O if available.
+
+  @retval partition entry list or NULL.
+**/
+MASTER_BOOT_RECORD *
+OcGetDiskMbrTable (
+  IN EFI_HANDLE  DiskHandle,
+  IN BOOLEAN     UseBlockIo2
+  );
+
 /**
   Creates a device path for a firmware file.
 
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 999cc037d1c..0a2463b7447 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -1994,7 +1994,7 @@ BuildFileSystemList (
     }
 
     for (Index = 0; Index < NoHandles; ++Index) {
-      LegacyOsType = InternalGetDiskLegacyOsType (Handles[Index], FALSE);
+      LegacyOsType = InternalGetPartitionLegacyOsType (Handles[Index]);
       if (LegacyOsType == OcLegacyOsTypeNone) {
         continue;
       }
diff --git a/Library/OcBootManagementLib/BootManagementInternal.h b/Library/OcBootManagementLib/BootManagementInternal.h
index e40f34b39d2..038e96bcecc 100644
--- a/Library/OcBootManagementLib/BootManagementInternal.h
+++ b/Library/OcBootManagementLib/BootManagementInternal.h
@@ -132,9 +132,8 @@ InternalLoadAppleLegacyInterface (
   );
 
 OC_LEGACY_OS_TYPE
-InternalGetDiskLegacyOsType (
-  IN  EFI_HANDLE  DiskHandle,
-  IN  BOOLEAN     UseBlockIo2
+InternalGetPartitionLegacyOsType (
+  IN  EFI_HANDLE  PartitionHandle
   );
 
 EFI_STATUS
diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index 9a81fe3096f..2e4aa5b8395 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -14,6 +14,8 @@
 
 #include "BootManagementInternal.h"
 
+#include <IndustryStandard/Mbr.h>
+
 #include <Protocol/DevicePath.h>
 
 #include <Library/BaseLib.h>
@@ -29,8 +31,6 @@
 #include <Library/UefiLib.h>
 #include <Library/UefiRuntimeServicesTableLib.h>
 
-#define MBR_SECTOR_SIZE  512
-
 //
 // PIWG firmware media device path for Apple legacy interface.
 // FwFile(2B0585EB-D8B8-49A9-8B8CE21B01AEF2B7)
@@ -237,44 +237,78 @@ InternalLoadAppleLegacyInterface (
 }
 
 OC_LEGACY_OS_TYPE
-InternalGetDiskLegacyOsType (
-  IN  EFI_HANDLE  DiskHandle,
-  IN  BOOLEAN     UseBlockIo2
+InternalGetPartitionLegacyOsType (
+  IN  EFI_HANDLE  PartitionHandle
   )
 {
-  EFI_STATUS         Status;
-  UINT8              *Buffer;
-  UINT32             BufferSize;
-  OC_LEGACY_OS_TYPE  LegacyOsType;
+  EFI_STATUS          Status;
+  MASTER_BOOT_RECORD  *Mbr;
+  MASTER_BOOT_RECORD  *Pbr;
+  OC_LEGACY_OS_TYPE   LegacyOsType;
 
-  OC_DISK_CONTEXT  DiskContext;
+  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
+  OC_DISK_CONTEXT           DiskContext;
+  EFI_HANDLE                DiskHandle;
 
-  ASSERT (DiskHandle != NULL);
+  ASSERT (PartitionHandle != NULL);
 
-  Status = OcDiskInitializeContext (&DiskContext, DiskHandle, UseBlockIo2);
-  if (EFI_ERROR (Status)) {
+  //
+  // Read MBR of whole disk.
+  //
+  DevicePath = DevicePathFromHandle (PartitionHandle);
+  if (DevicePath == NULL) {
     return OcLegacyOsTypeNone;
   }
 
+  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading MBR of disk", DevicePath);
+
+  DiskHandle = OcPartitionGetDiskHandle (DevicePath);
+  if (DiskHandle == NULL) {
+    return OcLegacyOsTypeNone;
+  }
+
+  Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
+  if (Mbr == NULL) {
+    DEBUG ((DEBUG_INFO, "OCB: Disk does not contain a valid MBR partition table\n"));
+    return OcLegacyOsTypeNone;
+  }
+
+  FreePool (Mbr);
+
   //
-  // Retrieve the first sector of the disk.
+  // Retrieve the first sector of the partition.
   //
-  BufferSize = ALIGN_VALUE (MBR_SECTOR_SIZE, DiskContext.BlockSize);
-  Buffer     = AllocatePool (BufferSize);
-  if (Buffer == NULL) {
-    DEBUG ((DEBUG_INFO, "OCBP: Buffer allocation error\n"));
+  Status = OcDiskInitializeContext (
+             &DiskContext,
+             PartitionHandle,
+             TRUE
+             );
+  if (EFI_ERROR (Status)) {
+    return OcLegacyOsTypeNone;
+  }
+
+  Pbr = (MASTER_BOOT_RECORD *)AllocatePool (MBR_SIZE);
+  if (Pbr == NULL) {
+    DEBUG ((DEBUG_INFO, "OCB: Buffer allocation error\n"));
     return OcLegacyOsTypeNone;
   }
 
   Status = OcDiskRead (
              &DiskContext,
              0,
-             BufferSize,
-             Buffer
+             MBR_SIZE,
+             Pbr
              );
-
   if (EFI_ERROR (Status)) {
-    FreePool (Buffer);
+    FreePool (Pbr);
+    return OcLegacyOsTypeNone;
+  }
+
+  //
+  // Validate signature in PBR.
+  //
+  if (Pbr->Signature != MBR_SIGNATURE) {
+    FreePool (Pbr);
     return OcLegacyOsTypeNone;
   }
 
@@ -283,13 +317,13 @@ InternalGetDiskLegacyOsType (
   // indicating the partition is bootable.
   //
   LegacyOsType = OcLegacyOsTypeNone;
-  if (CheckLegacySignature ("BOOTMGR", Buffer, BufferSize)) {
+  if (CheckLegacySignature ("BOOTMGR", Pbr, MBR_SIZE)) {
     LegacyOsType = OcLegacyOsTypeWindowsBootmgr;
-  } else if (CheckLegacySignature ("NTLDR", Buffer, BufferSize)) {
+  } else if (CheckLegacySignature ("NTLDR", Pbr, MBR_SIZE)) {
     LegacyOsType = OcLegacyOsTypeWindowsNtldr;
   }
 
-  FreePool (Buffer);
+  FreePool (Pbr);
 
   return LegacyOsType;
 }
diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index a2acd037499..4779d5940bc 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -14,6 +14,8 @@
 
 #include <Guid/Gpt.h>
 
+#include <IndustryStandard/Mbr.h>
+
 #include <Protocol/BlockIo.h>
 #include <Protocol/BlockIo2.h>
 #include <Protocol/DiskIo.h>
@@ -655,3 +657,68 @@ OcGetGptPartitionEntry (
 
   return PartEntry;
 }
+
+MASTER_BOOT_RECORD *
+OcGetDiskMbrTable (
+  IN EFI_HANDLE  DiskHandle,
+  IN BOOLEAN     UseBlockIo2
+  )
+{
+  EFI_STATUS          Status;
+  MASTER_BOOT_RECORD  *Mbr;
+  OC_DISK_CONTEXT     DiskContext;
+  UINTN               Index;
+  BOOLEAN             IsProtectiveMbr;
+
+  ASSERT (DiskHandle != NULL);
+
+  //
+  // Read first sector containing MBR table.
+  //
+  Status = OcDiskInitializeContext (&DiskContext, DiskHandle, UseBlockIo2);
+  if (EFI_ERROR (Status)) {
+    return NULL;
+  }
+
+  Mbr = (MASTER_BOOT_RECORD *)AllocatePool (sizeof (*Mbr));
+  if (Mbr == NULL) {
+    return NULL;
+  }
+
+  Status = OcDiskRead (&DiskContext, 0, sizeof (*Mbr), Mbr);
+  if (EFI_ERROR (Status)) {
+    FreePool (Mbr);
+    return NULL;
+  }
+
+  //
+  // Validate MBR signatures.
+  //
+  // If MBR is a protective one (as part of a GPT disk), ignore.
+  // Protective MBR is defined as a single partition of type 0xEE, other three partitions are to be zero.
+  //
+  if (Mbr->Signature != MBR_SIGNATURE) {
+    FreePool (Mbr);
+    return NULL;
+  }
+
+  if (  (Mbr->Partition[0].OSIndicator == PMBR_GPT_PARTITION)
+     && (*((UINT32 *)Mbr->Partition[0].StartingLBA) == 0x01)
+     && (*((UINT32 *)Mbr->Partition[0].SizeInLBA) != 0))
+  {
+    IsProtectiveMbr = TRUE;
+    for (Index = 1; Index < MAX_MBR_PARTITIONS; Index++) {
+      if ((*((UINT32 *)Mbr->Partition[Index].StartingLBA) != 0) || (*((UINT32 *)Mbr->Partition[Index].SizeInLBA) != 0)) {
+        IsProtectiveMbr = FALSE;
+        break;
+      }
+    }
+
+    if (IsProtectiveMbr) {
+      FreePool (Mbr);
+      return NULL;
+    }
+  }
+
+  return Mbr;
+}

From 3756798c7d70325a84c5521af6ca2958ede063bc Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 5 Aug 2023 12:25:02 -0500
Subject: [PATCH 09/55] OcBootManagementLib: Fix previous commit

---
 Library/OcBootManagementLib/LegacyBootSupport.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index 2e4aa5b8395..79d1b21bf5b 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -47,16 +47,15 @@ static CONST EFI_DEVICE_PATH_PROTOCOL  *AppleLegacyInterfaceMediaDevicePathPath
 STATIC
 BOOLEAN
 CheckLegacySignature (
-  IN CONST CHAR8  *SignatureStr,
-  IN UINT8        *Buffer,
-  IN UINT32       BufferSize
+  IN CONST CHAR8         *SignatureStr,
+  IN MASTER_BOOT_RECORD  *Pbr
   )
 {
   UINT32  Offset;
 
   Offset = 0;
 
-  return FindPattern ((CONST UINT8 *)SignatureStr, NULL, (CONST UINT32)AsciiStrLen (SignatureStr), Buffer, BufferSize, &Offset);
+  return FindPattern ((CONST UINT8 *)SignatureStr, NULL, (CONST UINT32)AsciiStrLen (SignatureStr), (CONST UINT8 *)Pbr, sizeof (*Pbr), &Offset);
 }
 
 STATIC
@@ -317,9 +316,9 @@ InternalGetPartitionLegacyOsType (
   // indicating the partition is bootable.
   //
   LegacyOsType = OcLegacyOsTypeNone;
-  if (CheckLegacySignature ("BOOTMGR", Pbr, MBR_SIZE)) {
+  if (CheckLegacySignature ("BOOTMGR", Pbr)) {
     LegacyOsType = OcLegacyOsTypeWindowsBootmgr;
-  } else if (CheckLegacySignature ("NTLDR", Pbr, MBR_SIZE)) {
+  } else if (CheckLegacySignature ("NTLDR", Pbr)) {
     LegacyOsType = OcLegacyOsTypeWindowsNtldr;
   }
 

From 323a42003ac279e924584423823db7086bcc4dbc Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 5 Aug 2023 16:05:07 -0500
Subject: [PATCH 10/55] OcBootManagementLib: Handle legacy default boot entry

---
 Include/Acidanthera/Library/OcFileLib.h       |   6 +
 .../OcBootManagementLib/BootEntryManagement.c | 293 ++++++++++--------
 Library/OcFileLib/DiskMisc.c                  | 120 ++++++-
 3 files changed, 289 insertions(+), 130 deletions(-)

diff --git a/Include/Acidanthera/Library/OcFileLib.h b/Include/Acidanthera/Library/OcFileLib.h
index 2b923781be1..e5ee7bf1094 100644
--- a/Include/Acidanthera/Library/OcFileLib.h
+++ b/Include/Acidanthera/Library/OcFileLib.h
@@ -618,6 +618,12 @@ OcGetDiskMbrTable (
   IN BOOLEAN     UseBlockIo2
   );
 
+EFI_DEVICE_PATH_PROTOCOL *
+OcDiskFindActiveMbrPartitionPath (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
+  OUT UINTN                     *PartitionDevicePathSize
+  );
+
 /**
   Creates a device path for a firmware file.
 
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 0a2463b7447..89a1deaea3f 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -1173,6 +1173,97 @@ AddBootEntryFromSelfRecovery (
   return Status;
 }
 
+/**
+  Create bootable entries from legacy boot partitons.
+
+  @param[in,out] BootContext   Context of filesystems.
+  @param[in,out] FileSystem    Filesystem to scan for recovery.
+
+  @retval EFI_SUCCESS on success.
+**/
+STATIC
+EFI_STATUS
+AddBootEntryFromLegacyPartition (
+  IN OUT OC_BOOT_CONTEXT     *BootContext,
+  IN OUT OC_BOOT_FILESYSTEM  *FileSystem
+  )
+{
+  EFI_STATUS                Status;
+  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
+  OC_BOOT_ENTRY             *BootEntry;
+
+  //
+  // Only support legacy filesystems.
+  //
+  if (FileSystem->LegacyOsType == OcLegacyOsTypeNone) {
+    return EFI_UNSUPPORTED;
+  }
+
+  Status = gBS->HandleProtocol (
+                  FileSystem->Handle,
+                  &gEfiDevicePathProtocolGuid,
+                  (VOID **)&DevicePath
+                  );
+  if (EFI_ERROR (Status)) {
+    return EFI_UNSUPPORTED;
+  }
+
+  DebugPrintDevicePath (DEBUG_INFO, "OCB: Adding legacy entry for disk", DevicePath);
+
+  //
+  // Allocate, initialise, and describe boot entry.
+  //
+  BootEntry = AllocateZeroPool (sizeof (*BootEntry));
+  if (BootEntry == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  BootEntry->DevicePath = DuplicateDevicePath (DevicePath);
+  if (BootEntry->DevicePath == NULL) {
+    FreePool (BootEntry);
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  BootEntry->IsExternal   = FileSystem->External;
+  BootEntry->LegacyOsType = FileSystem->LegacyOsType;
+  BootEntry->LaunchInText = TRUE;
+
+  //
+  // Load options are set based on type of disk.
+  // Internal disk = "HD"
+  // External disk = "USB"
+  // Optical disk  = "CD"
+  //
+  // TODO: Support optical media.
+  //
+  if (BootEntry->IsExternal) {
+    BootEntry->LoadOptionsSize = L_STR_SIZE ("USB");
+    BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("USB"), "USB");
+  } else {
+    BootEntry->LoadOptionsSize = L_STR_SIZE ("HD");
+    BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
+  }
+
+  if (BootEntry->LoadOptions == NULL) {
+    FreePool (BootEntry);
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  Status = InternalDescribeLegacyBootEntry (BootContext, FileSystem->LegacyOsType, BootEntry);
+  if (EFI_ERROR (Status)) {
+    FreePool (BootEntry);
+    return Status;
+  }
+
+  RegisterBootOption (
+    BootContext,
+    FileSystem,
+    BootEntry
+    );
+
+  return EFI_SUCCESS;
+}
+
 /**
   Create bootable entries from boot options.
 
@@ -1209,11 +1300,13 @@ AddBootEntryFromBootOption (
   EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
   EFI_DEVICE_PATH_PROTOCOL  *RemainingDevicePath;
   EFI_DEVICE_PATH_PROTOCOL  *ExpandedDevicePath;
+  EFI_DEVICE_PATH_PROTOCOL  *ActivePartitionDevicePath;
   EFI_HANDLE                FileSystemHandle;
   OC_BOOT_FILESYSTEM        *FileSystem;
   UINTN                     DevicePathSize;
   INTN                      NumPatchedNodes;
   BOOLEAN                   IsAppleLegacy;
+  BOOLEAN                   IsLegacyEntry;
   BOOLEAN                   IsRoot;
   EFI_LOAD_OPTION           *LoadOption;
   UINTN                     LoadOptionSize;
@@ -1262,6 +1355,7 @@ AddBootEntryFromBootOption (
   // BootCamp device path will point to disk instead of partition.
   //
   IsAppleLegacy = InternalIsAppleLegacyLoadApp (DevicePath);
+  IsLegacyEntry = FALSE;
   if (IsAppleLegacy) {
     FreePool (DevicePath);
     Status = GetVariable2 (
@@ -1303,7 +1397,15 @@ AddBootEntryFromBootOption (
   }
 
   //
-  // Expand BootCamp device path to EFI partition device path.
+  // Handle Apple BootCamp device path.
+  //
+  // If we have a legacy installation of Windows in place, Device Path
+  // will point to disk containing the active partition to boot. This will
+  // need to be expanded to the full Device Path of the active partition.
+  //
+  // If not, locate the EFI partition Device Path to boot Windows in UEFI mode.
+  // Installing Windows on Macs that normally use legacy mode for Boot Camp
+  // will exhibit this behavior if Windows is selected as a startup disk from within macOS.
   //
   if (IsAppleLegacy) {
     //
@@ -1316,12 +1418,36 @@ AddBootEntryFromBootOption (
       return EFI_NOT_FOUND;
     }
 
-    RemainingDevicePath = DevicePath;
-    DevicePath          = OcDiskFindSystemPartitionPath (
-                            DevicePath,
-                            &DevicePathSize,
-                            &FileSystemHandle
-                            );
+    //
+    // Attempt to locate active MBR partition Device Path.
+    //
+    RemainingDevicePath       = DevicePath;
+    ActivePartitionDevicePath = OcDiskFindActiveMbrPartitionPath (
+                                  DevicePath,
+                                  &DevicePathSize
+                                  );
+    if (ActivePartitionDevicePath != NULL) {
+      DevicePath = ActivePartitionDevicePath;
+      Status     = gBS->LocateDevicePath (
+                          &gEfiBlockIoProtocolGuid,
+                          &ActivePartitionDevicePath,
+                          &FileSystemHandle
+                          );
+
+      if (!EFI_ERROR (Status)) {
+        IsLegacyEntry = TRUE;
+      }
+
+      //
+      // Expand BootCamp device path to EFI partition device path.
+      //
+    } else {
+      DevicePath = OcDiskFindSystemPartitionPath (
+                     DevicePath,
+                     &DevicePathSize,
+                     &FileSystemHandle
+                     );
+    }
 
     FreePool (RemainingDevicePath);
 
@@ -1341,8 +1467,9 @@ AddBootEntryFromBootOption (
     }
 
     //
-    // The Device Path returned by OcDiskFindSystemPartitionPath() is a pointer
-    // to an installed protocol. Duplicate it so we own the memory.
+    // The Device Path returned by OcDiskFindActiveMbrPartitionPath() and
+    // OcDiskFindSystemPartitionPath() is a pointer to an installed protocol.
+    // Duplicate it so we own the memory.
     //
     if (DevicePath != NULL) {
       DevicePath = AllocateCopyPool (DevicePathSize, DevicePath);
@@ -1565,125 +1692,41 @@ AddBootEntryFromBootOption (
     FreePool (DevicePath);
   }
 
-  //
-  // We may have a Boot#### entry pointing to macOS with full DP (up to boot.efi),
-  // so IsRoot will be true. However, if this is APFS, we may still have:
-  // - Recovery for this macOS.
-  // - Another macOS installation.
-  // We can only detect them with bless, so we invoke bless in deduplication mode.
-  // We also detect only the Core Apple Boot Policy predefined booter paths to
-  // avoid detection of e.g. generic booters (such as BOOTx64) to avoid
-  // duplicates.
-  //
-  // The amount of paths depends on the kind of the entry.
-  // - If this is a root entry (i.e. it points to the partition)
-  //   we invoke full bless, as it may be Windows entry created by legacy NVRAM script.
-  // - If this is a full entry (i.e. it points to the bootloader)
-  //   we invoke partial bless, which ignores BOOTx64.efi.
-  //   Ignoring BOOTx64.efi is important as we may already have bootmgfw.efi as our entry,
-  //   and we do not want to see Windows added twice.
-  //
-  Status = AddBootEntryFromBless (
-             BootContext,
-             FileSystem,
-             gAppleBootPolicyPredefinedPaths,
-             IsRoot ? gAppleBootPolicyNumPredefinedPaths : gAppleBootPolicyCoreNumPredefinedPaths,
-             LazyScan,
-             TRUE
-             );
-
-  return Status;
-}
-
-/**
-  Create bootable entries from legacy boot partitons.
-
-  @param[in,out] BootContext   Context of filesystems.
-  @param[in,out] FileSystem    Filesystem to scan for recovery.
-
-  @retval EFI_SUCCESS on success.
-**/
-STATIC
-EFI_STATUS
-AddBootEntryFromLegacyPartition (
-  IN OUT OC_BOOT_CONTEXT     *BootContext,
-  IN OUT OC_BOOT_FILESYSTEM  *FileSystem
-  )
-{
-  EFI_STATUS                Status;
-  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
-  OC_BOOT_ENTRY             *BootEntry;
-
-  //
-  // Only support legacy filesystems.
-  //
-  if (FileSystem->LegacyOsType == OcLegacyOsTypeNone) {
-    return EFI_UNSUPPORTED;
-  }
-
-  Status = gBS->HandleProtocol (
-                  FileSystem->Handle,
-                  &gEfiDevicePathProtocolGuid,
-                  (VOID **)&DevicePath
-                  );
-  if (EFI_ERROR (Status)) {
-    return EFI_UNSUPPORTED;
-  }
-
-  DebugPrintDevicePath (DEBUG_INFO, "OCB: Adding legacy entry for disk", DevicePath);
-
-  //
-  // Allocate, initialise, and describe boot entry.
-  //
-  BootEntry = AllocateZeroPool (sizeof (*BootEntry));
-  if (BootEntry == NULL) {
-    return EFI_OUT_OF_RESOURCES;
-  }
-
-  BootEntry->DevicePath = DuplicateDevicePath (DevicePath);
-  if (BootEntry->DevicePath == NULL) {
-    FreePool (BootEntry);
-    return EFI_OUT_OF_RESOURCES;
-  }
-
-  BootEntry->IsExternal   = FileSystem->External;
-  BootEntry->LegacyOsType = FileSystem->LegacyOsType;
-  BootEntry->LaunchInText = TRUE;
-
-  //
-  // Load options are set based on type of disk.
-  // Internal disk = "HD"
-  // External disk = "USB"
-  // Optical disk  = "CD"
-  //
-  // TODO: Support optical media.
-  //
-  if (BootEntry->IsExternal) {
-    BootEntry->LoadOptionsSize = L_STR_SIZE ("USB");
-    BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("USB"), "USB");
+  if (IsLegacyEntry) {
+    Status = AddBootEntryFromLegacyPartition (
+               BootContext,
+               FileSystem
+               );
   } else {
-    BootEntry->LoadOptionsSize = L_STR_SIZE ("HD");
-    BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
-  }
-
-  if (BootEntry->LoadOptions == NULL) {
-    FreePool (BootEntry);
-    return EFI_OUT_OF_RESOURCES;
-  }
-
-  Status = InternalDescribeLegacyBootEntry (BootContext, FileSystem->LegacyOsType, BootEntry);
-  if (EFI_ERROR (Status)) {
-    FreePool (BootEntry);
-    return Status;
+    //
+    // We may have a Boot#### entry pointing to macOS with full DP (up to boot.efi),
+    // so IsRoot will be true. However, if this is APFS, we may still have:
+    // - Recovery for this macOS.
+    // - Another macOS installation.
+    // We can only detect them with bless, so we invoke bless in deduplication mode.
+    // We also detect only the Core Apple Boot Policy predefined booter paths to
+    // avoid detection of e.g. generic booters (such as BOOTx64) to avoid
+    // duplicates.
+    //
+    // The amount of paths depends on the kind of the entry.
+    // - If this is a root entry (i.e. it points to the partition)
+    //   we invoke full bless, as it may be Windows entry created by legacy NVRAM script.
+    // - If this is a full entry (i.e. it points to the bootloader)
+    //   we invoke partial bless, which ignores BOOTx64.efi.
+    //   Ignoring BOOTx64.efi is important as we may already have bootmgfw.efi as our entry,
+    //   and we do not want to see Windows added twice.
+    //
+    Status = AddBootEntryFromBless (
+               BootContext,
+               FileSystem,
+               gAppleBootPolicyPredefinedPaths,
+               IsRoot ? gAppleBootPolicyNumPredefinedPaths : gAppleBootPolicyCoreNumPredefinedPaths,
+               LazyScan,
+               TRUE
+               );
   }
 
-  RegisterBootOption (
-    BootContext,
-    FileSystem,
-    BootEntry
-    );
-
-  return EFI_SUCCESS;
+  return Status;
 }
 
 /**
diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index 4779d5940bc..1467cc1800e 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -173,8 +173,9 @@ InternalDebugPrintPartitionEntry (
 
 STATIC
 EFI_HANDLE
-InternalPartitionGetDiskHandle (
+InternalGetDiskHandle (
   IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath,
+  IN  BOOLEAN                   IsPartitionPath,
   OUT BOOLEAN                   *HasBlockIo2
   )
 {
@@ -188,7 +189,12 @@ InternalPartitionGetDiskHandle (
   ASSERT (HdDevicePath != NULL);
   ASSERT (HasBlockIo2 != NULL);
 
-  DiskPath = OcDiskGetDevicePath (HdDevicePath);
+  if (IsPartitionPath) {
+    DiskPath = OcDiskGetDevicePath (HdDevicePath);
+  } else {
+    DiskPath = HdDevicePath;
+  }
+
   TempPath = DiskPath;
   Status   = gBS->LocateDevicePath (
                     &gEfiBlockIo2ProtocolGuid,
@@ -216,7 +222,9 @@ InternalPartitionGetDiskHandle (
     DiskHandle = NULL;
   }
 
-  FreePool (DiskPath);
+  if (IsPartitionPath && (DiskPath != NULL)) {
+    FreePool (DiskPath);
+  }
 
   return DiskHandle;
 }
@@ -283,8 +291,9 @@ OcPartitionGetDiskHandle (
 
   ASSERT (HdDevicePath != NULL);
 
-  return InternalPartitionGetDiskHandle (
+  return InternalGetDiskHandle (
            HdDevicePath,
+           TRUE,
            &Dummy
            );
 }
@@ -611,8 +620,9 @@ OcGetGptPartitionEntry (
     return NULL;
   }
 
-  DiskHandle = InternalPartitionGetDiskHandle (
+  DiskHandle = InternalGetDiskHandle (
                  FsDevicePath,
+                 TRUE,
                  &HasBlockIo2
                  );
   if (DiskHandle == NULL) {
@@ -722,3 +732,103 @@ OcGetDiskMbrTable (
 
   return Mbr;
 }
+
+EFI_DEVICE_PATH_PROTOCOL *
+OcDiskFindActiveMbrPartitionPath (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
+  OUT UINTN                     *PartitionDevicePathSize
+  )
+{
+  EFI_STATUS  Status;
+  EFI_HANDLE  DiskHandle;
+  BOOLEAN     HasBlockIo2;
+  UINTN       Index;
+  INT32       ActivePartition;
+
+  UINTN                     NoHandles;
+  EFI_HANDLE                *Handles;
+  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
+  HARDDRIVE_DEVICE_PATH     *HdNode;
+  MASTER_BOOT_RECORD        *Mbr;
+
+  ASSERT (DiskDevicePath != NULL);
+  ASSERT (PartitionDevicePathSize != NULL);
+
+  //
+  // Get MBR partition table from disk.
+  //
+  DiskHandle = InternalGetDiskHandle (
+                 DiskDevicePath,
+                 FALSE,
+                 &HasBlockIo2
+                 );
+  if (DiskHandle == NULL) {
+    return NULL;
+  }
+
+  Mbr = OcGetDiskMbrTable (
+          DiskHandle,
+          HasBlockIo2
+          );
+  if (Mbr == NULL) {
+    return NULL;
+  }
+
+  //
+  // Determine active partition based on first one with active partition set.
+  // Multiple active partitions should not occur but possible.
+  //
+  ActivePartition = -1;
+  for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
+    if (Mbr->Partition[Index].BootIndicator == 0x80) {
+      ActivePartition = (INT32)Index;
+    }
+  }
+
+  //
+  // No active partitions present.
+  //
+  if (ActivePartition == -1) {
+    DEBUG ((DEBUG_INFO, "OCPI: No active partitions found in MBR\n"));
+    FreePool (Mbr);
+    return NULL;
+  }
+
+  Status = gBS->LocateHandleBuffer (
+                  ByProtocol,
+                  &gEfiBlockIoProtocolGuid,
+                  NULL,
+                  &NoHandles,
+                  &Handles
+                  );
+  if (EFI_ERROR (Status)) {
+    FreePool (Mbr);
+    return NULL;
+  }
+
+  for (Index = 0; Index < NoHandles; Index++) {
+    DevicePath = DevicePathFromHandle (Handles[Index]);
+    if (DevicePath == NULL) {
+      continue;
+    }
+
+    if (CompareMem (DevicePath, DiskDevicePath, GetDevicePathSize (DiskDevicePath) - END_DEVICE_PATH_LENGTH) == 0) {
+      HdNode = (HARDDRIVE_DEVICE_PATH *)FindDevicePathNodeWithType (
+                                          DevicePath,
+                                          MEDIA_DEVICE_PATH,
+                                          MEDIA_HARDDRIVE_DP
+                                          );
+      if (HdNode != NULL) {
+        if (HdNode->PartitionStart == *((UINT32 *)Mbr->Partition[ActivePartition].StartingLBA)) {
+          DebugPrintDevicePath (DEBUG_INFO, "OCPI: Got active MBR partition device path", DevicePath);
+          FreePool (Mbr);
+          *PartitionDevicePathSize = GetDevicePathSize (DevicePath);
+          return DevicePath;
+        }
+      }
+    }
+  }
+
+  FreePool (Mbr);
+  return NULL;
+}

From 9fd5aae44fb2013f559acfb9178f43d51410c311 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 5 Aug 2023 19:24:01 -0500
Subject: [PATCH 11/55] OcBootManagementLib: Fix hang on certain Mac models
 during legacy start

---
 Library/OcBootManagementLib/PolicyManagement.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Library/OcBootManagementLib/PolicyManagement.c b/Library/OcBootManagementLib/PolicyManagement.c
index 5fe66fea4ca..d1aa1119d53 100644
--- a/Library/OcBootManagementLib/PolicyManagement.c
+++ b/Library/OcBootManagementLib/PolicyManagement.c
@@ -336,6 +336,16 @@ OcGetBootDevicePathType (
     *IsFolder = FALSE;
   }
 
+  //
+  // Detect firmware images such as the Apple legacy loader interface.
+  //
+  // Certain Mac models lock up if any additional probing of the device path
+  // is performed when the Apple legacy loader interface is being started.
+  //
+  if (DevicePath->Type == MEDIA_DEVICE_PATH && DevicePath->SubType == MEDIA_PIWG_FW_FILE_DP) {
+    return OC_BOOT_UNKNOWN;
+  }
+
   Path = OcCopyDevicePathFullName (DevicePath, NULL);
   if (Path == NULL) {
     return OC_BOOT_UNKNOWN;

From f93f52b20c7e9b8a4c33abab23bddf184cc0a031 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 5 Aug 2023 19:29:08 -0500
Subject: [PATCH 12/55] OcBootManagementLib: Cleanup MBR detecting logging

---
 Library/OcBootManagementLib/LegacyBootSupport.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index 79d1b21bf5b..f7df960d6df 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -259,8 +259,6 @@ InternalGetPartitionLegacyOsType (
     return OcLegacyOsTypeNone;
   }
 
-  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading MBR of disk", DevicePath);
-
   DiskHandle = OcPartitionGetDiskHandle (DevicePath);
   if (DiskHandle == NULL) {
     return OcLegacyOsTypeNone;
@@ -268,7 +266,7 @@ InternalGetPartitionLegacyOsType (
 
   Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
   if (Mbr == NULL) {
-    DEBUG ((DEBUG_INFO, "OCB: Disk does not contain a valid MBR partition table\n"));
+    DEBUG ((DEBUG_VERBOSE, "OCB: Disk does not contain a valid MBR partition table\n"));
     return OcLegacyOsTypeNone;
   }
 
@@ -277,6 +275,7 @@ InternalGetPartitionLegacyOsType (
   //
   // Retrieve the first sector of the partition.
   //
+  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading MBR of disk", DevicePath);
   Status = OcDiskInitializeContext (
              &DiskContext,
              PartitionHandle,

From b26ce6e7f8db94a22007b7b792dfa71a819b3e5a Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 5 Aug 2023 19:41:42 -0500
Subject: [PATCH 13/55] OcBootManagementLib: Fix logging

---
 Library/OcBootManagementLib/LegacyBootSupport.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index f7df960d6df..cbdbdd559e1 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -258,6 +258,7 @@ InternalGetPartitionLegacyOsType (
   if (DevicePath == NULL) {
     return OcLegacyOsTypeNone;
   }
+  DebugPrintDevicePath (DEBUG_VERBOSE, "OCB: Reading MBR for disk", DevicePath);
 
   DiskHandle = OcPartitionGetDiskHandle (DevicePath);
   if (DiskHandle == NULL) {
@@ -275,7 +276,7 @@ InternalGetPartitionLegacyOsType (
   //
   // Retrieve the first sector of the partition.
   //
-  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading MBR of disk", DevicePath);
+  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading PBR for partition", DevicePath);
   Status = OcDiskInitializeContext (
              &DiskContext,
              PartitionHandle,

From 52b6eb72ce6682b834346cc379bd25d12f83a3cd Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 5 Aug 2023 22:24:17 -0500
Subject: [PATCH 14/55] OcBootManagementLib: Fix assertion for unknown legacy
 OS name

---
 Library/OcBootManagementLib/BootEntryInfo.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Library/OcBootManagementLib/BootEntryInfo.c b/Library/OcBootManagementLib/BootEntryInfo.c
index 4171e8d94a5..984944e7b8b 100644
--- a/Library/OcBootManagementLib/BootEntryInfo.c
+++ b/Library/OcBootManagementLib/BootEntryInfo.c
@@ -911,6 +911,8 @@ InternalDescribeLegacyBootEntry (
       break;
 
     default:
+      BootEntry->Type = OC_BOOT_UNKNOWN;
+      BootEntry->Name = AllocateCopyPool (sizeof (L"Unknown OS (legacy)"), L"Unknown OS (legacy)");
       break;
   }
 

From a4cb596b7c796d02394e7bac3da06e9f85f91516 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 5 Aug 2023 22:27:38 -0500
Subject: [PATCH 15/55] OcBootManagementLib: Add legacy CD boot support

---
 .../Acidanthera/Library/OcBootManagementLib.h |   3 +-
 Include/Acidanthera/Library/OcFileLib.h       |  12 ++
 .../OcBootManagementLib/BootEntryManagement.c |  11 +-
 .../OcBootManagementLib/LegacyBootSupport.c   | 132 +++++++++++-------
 .../OcBootManagementLib/PolicyManagement.c    |  15 +-
 Library/OcFileLib/DiskMisc.c                  |  69 +++++++--
 6 files changed, 168 insertions(+), 74 deletions(-)

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index 934dd6095fe..4966683133b 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -167,7 +167,8 @@ typedef enum OC_LEGACY_BOOT_TYPE_ {
 typedef enum OC_LEGACY_OS_TYPE_ {
   OcLegacyOsTypeNone,
   OcLegacyOsTypeWindowsNtldr,
-  OcLegacyOsTypeWindowsBootmgr
+  OcLegacyOsTypeWindowsBootmgr,
+  OcLegacyOsTypeIsoLinux
 } OC_LEGACY_OS_TYPE;
 
 /**
diff --git a/Include/Acidanthera/Library/OcFileLib.h b/Include/Acidanthera/Library/OcFileLib.h
index e5ee7bf1094..c7c3c178467 100644
--- a/Include/Acidanthera/Library/OcFileLib.h
+++ b/Include/Acidanthera/Library/OcFileLib.h
@@ -508,6 +508,18 @@ OcPartitionGetDiskHandle (
   IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   );
 
+/**
+  Check if disk is a CD-ROM device.
+
+  @param[in] HdDevicePath  The Device Path of the disk.
+
+  @retval Device Path or NULL
+**/
+BOOLEAN
+OcIsDiskCdRom (
+  IN EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath
+  );
+
 /**
   Locate the disk's EFI System Partition.
 
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 89a1deaea3f..af98f546de9 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -1234,11 +1234,14 @@ AddBootEntryFromLegacyPartition (
   // External disk = "USB"
   // Optical disk  = "CD"
   //
-  // TODO: Support optical media.
-  //
   if (BootEntry->IsExternal) {
-    BootEntry->LoadOptionsSize = L_STR_SIZE ("USB");
-    BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("USB"), "USB");
+    if (OcIsDiskCdRom (BootEntry->DevicePath)) {
+      BootEntry->LoadOptionsSize = L_STR_SIZE ("CD");
+      BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("CD"), "CD");
+    } else {
+      BootEntry->LoadOptionsSize = L_STR_SIZE ("USB");
+      BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("USB"), "USB");
+    }
   } else {
     BootEntry->LoadOptionsSize = L_STR_SIZE ("HD");
     BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index cbdbdd559e1..fc4ffeeb6e4 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -55,7 +55,14 @@ CheckLegacySignature (
 
   Offset = 0;
 
-  return FindPattern ((CONST UINT8 *)SignatureStr, NULL, (CONST UINT32)AsciiStrLen (SignatureStr), (CONST UINT8 *)Pbr, sizeof (*Pbr), &Offset);
+  return FindPattern (
+           (CONST UINT8 *)SignatureStr,
+           NULL,
+           (CONST UINT32)AsciiStrLen (SignatureStr),
+           Pbr->BootStrapCode,
+           sizeof (Pbr->BootStrapCode),
+           &Offset
+           );
 }
 
 STATIC
@@ -166,28 +173,30 @@ InternalLoadAppleLegacyInterface (
   // Get device path to disk to be booted.
   // TODO: Handle CD booting, device path is not required in that case.
   //
-  WholeDiskPath = OcDiskGetDevicePath (HdDevicePath);
-  if (WholeDiskPath == NULL) {
-    return EFI_INVALID_PARAMETER;
-  }
+  if (!OcIsDiskCdRom (HdDevicePath)) {
+    WholeDiskPath = OcDiskGetDevicePath (HdDevicePath);
+    if (WholeDiskPath == NULL) {
+      return EFI_INVALID_PARAMETER;
+    }
 
-  DebugPrintDevicePath (DEBUG_INFO, "OCB: Legacy disk device path", WholeDiskPath);
+    DebugPrintDevicePath (DEBUG_INFO, "OCB: Legacy disk device path", WholeDiskPath);
 
-  // TODO: Mark target partition as active on pure MBR and hybrid GPT disks.
-  // Macs only boot the active partition.
+    // TODO: Mark target partition as active on pure MBR and hybrid GPT disks.
+    // Macs only boot the active partition.
 
-  //
-  // Set BootCampHD variable pointing to target disk.
-  //
-  Status = gRT->SetVariable (
-                  APPLE_BOOT_CAMP_HD_VARIABLE_NAME,
-                  &gAppleBootVariableGuid,
-                  EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
-                  GetDevicePathSize (WholeDiskPath),
-                  WholeDiskPath
-                  );
-  if (EFI_ERROR (Status)) {
-    return Status;
+    //
+    // Set BootCampHD variable pointing to target disk.
+    //
+    Status = gRT->SetVariable (
+                    APPLE_BOOT_CAMP_HD_VARIABLE_NAME,
+                    &gAppleBootVariableGuid,
+                    EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
+                    GetDevicePathSize (WholeDiskPath),
+                    WholeDiskPath
+                    );
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
   }
 
   //
@@ -242,7 +251,7 @@ InternalGetPartitionLegacyOsType (
 {
   EFI_STATUS          Status;
   MASTER_BOOT_RECORD  *Mbr;
-  MASTER_BOOT_RECORD  *Pbr;
+  UINTN               MbrSize;
   OC_LEGACY_OS_TYPE   LegacyOsType;
 
   EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
@@ -258,6 +267,7 @@ InternalGetPartitionLegacyOsType (
   if (DevicePath == NULL) {
     return OcLegacyOsTypeNone;
   }
+
   DebugPrintDevicePath (DEBUG_VERBOSE, "OCB: Reading MBR for disk", DevicePath);
 
   DiskHandle = OcPartitionGetDiskHandle (DevicePath);
@@ -271,43 +281,51 @@ InternalGetPartitionLegacyOsType (
     return OcLegacyOsTypeNone;
   }
 
-  FreePool (Mbr);
-
   //
-  // Retrieve the first sector of the partition.
+  // For hard disk devices, get PBR sector instead.
   //
-  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading PBR for partition", DevicePath);
-  Status = OcDiskInitializeContext (
-             &DiskContext,
-             PartitionHandle,
-             TRUE
-             );
-  if (EFI_ERROR (Status)) {
-    return OcLegacyOsTypeNone;
-  }
+  if (!OcIsDiskCdRom (DevicePath)) {
+    FreePool (Mbr);
 
-  Pbr = (MASTER_BOOT_RECORD *)AllocatePool (MBR_SIZE);
-  if (Pbr == NULL) {
-    DEBUG ((DEBUG_INFO, "OCB: Buffer allocation error\n"));
-    return OcLegacyOsTypeNone;
-  }
+    //
+    // Retrieve the first sector of the partition.
+    //
+    DebugPrintDevicePath (DEBUG_VERBOSE, "OCB: Reading PBR for partition", DevicePath);
+    Status = OcDiskInitializeContext (
+               &DiskContext,
+               PartitionHandle,
+               TRUE
+               );
+    if (EFI_ERROR (Status)) {
+      return OcLegacyOsTypeNone;
+    }
 
-  Status = OcDiskRead (
-             &DiskContext,
-             0,
-             MBR_SIZE,
-             Pbr
-             );
-  if (EFI_ERROR (Status)) {
-    FreePool (Pbr);
-    return OcLegacyOsTypeNone;
+    MbrSize = ALIGN_VALUE (sizeof (*Mbr), DiskContext.BlockSize);
+    Mbr     = (MASTER_BOOT_RECORD *)AllocatePool (MbrSize);
+    if (Mbr == NULL) {
+      DEBUG ((DEBUG_INFO, "OCB: Buffer allocation error\n"));
+      return OcLegacyOsTypeNone;
+    }
+
+    Status = OcDiskRead (
+               &DiskContext,
+               0,
+               MbrSize,
+               Mbr
+               );
+    if (EFI_ERROR (Status)) {
+      FreePool (Mbr);
+      return OcLegacyOsTypeNone;
+    }
   }
 
+  DebugPrintHexDump (DEBUG_INFO, "OCB: MbrHEX", Mbr->BootStrapCode, sizeof (Mbr->BootStrapCode));
+
   //
-  // Validate signature in PBR.
+  // Validate signature in MBR.
   //
-  if (Pbr->Signature != MBR_SIGNATURE) {
-    FreePool (Pbr);
+  if (Mbr->Signature != MBR_SIGNATURE) {
+    FreePool (Mbr);
     return OcLegacyOsTypeNone;
   }
 
@@ -315,14 +333,20 @@ InternalGetPartitionLegacyOsType (
   // Validate sector contents and check for known signatures
   // indicating the partition is bootable.
   //
-  LegacyOsType = OcLegacyOsTypeNone;
-  if (CheckLegacySignature ("BOOTMGR", Pbr)) {
+  if (CheckLegacySignature ("BOOTMGR", Mbr)) {
     LegacyOsType = OcLegacyOsTypeWindowsBootmgr;
-  } else if (CheckLegacySignature ("NTLDR", Pbr)) {
+  } else if (CheckLegacySignature ("NTLDR", Mbr)) {
     LegacyOsType = OcLegacyOsTypeWindowsNtldr;
+  } else if (  CheckLegacySignature ("ISOLINUX", Mbr)
+            || CheckLegacySignature ("isolinux", Mbr))
+  {
+    LegacyOsType = OcLegacyOsTypeIsoLinux;
+  } else {
+    LegacyOsType = OcLegacyOsTypeNone;
+    DEBUG ((DEBUG_INFO, "OCB: Unknown legacy bootsector signature\n"));
   }
 
-  FreePool (Pbr);
+  FreePool (Mbr);
 
   return LegacyOsType;
 }
diff --git a/Library/OcBootManagementLib/PolicyManagement.c b/Library/OcBootManagementLib/PolicyManagement.c
index d1aa1119d53..61d5e9c69b8 100644
--- a/Library/OcBootManagementLib/PolicyManagement.c
+++ b/Library/OcBootManagementLib/PolicyManagement.c
@@ -75,6 +75,19 @@ OcGetDevicePolicyType (
       SubType = DevicePathSubType (DevicePathWalker);
       switch (SubType) {
         case MSG_SATA_DP:
+          //
+          // Check if this SATA Bus has a CD connected.
+          //
+          DevicePathWalker = NextDevicePathNode (DevicePathWalker);
+          if (  !IsDevicePathEnd (DevicePathWalker)
+             && (DevicePathType (DevicePathWalker) == MEDIA_DEVICE_PATH)
+             && (DevicePathSubType (DevicePathWalker) == MEDIA_CDROM_DP))
+          {
+            if (External != NULL) {
+              *External = TRUE;
+            }
+          }
+
           return OC_SCAN_ALLOW_DEVICE_SATA;
         case MSG_SASEX_DP:
           return OC_SCAN_ALLOW_DEVICE_SASEX;
@@ -342,7 +355,7 @@ OcGetBootDevicePathType (
   // Certain Mac models lock up if any additional probing of the device path
   // is performed when the Apple legacy loader interface is being started.
   //
-  if (DevicePath->Type == MEDIA_DEVICE_PATH && DevicePath->SubType == MEDIA_PIWG_FW_FILE_DP) {
+  if ((DevicePath->Type == MEDIA_DEVICE_PATH) && (DevicePath->SubType == MEDIA_PIWG_FW_FILE_DP)) {
     return OC_BOOT_UNKNOWN;
   }
 
diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index 1467cc1800e..e6f228197bf 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -241,21 +241,28 @@ OcDiskGetDevicePath (
   IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   )
 {
-  EFI_DEVICE_PATH_PROTOCOL     *PrefixPath;
-  EFI_DEVICE_PATH_PROTOCOL     *TempPath;
-  CONST HARDDRIVE_DEVICE_PATH  *HdNode;
+  EFI_DEVICE_PATH_PROTOCOL        *PrefixPath;
+  EFI_DEVICE_PATH_PROTOCOL        *TempPath;
+  CONST EFI_DEVICE_PATH_PROTOCOL  *HdNode;
 
   ASSERT (HdDevicePath != NULL);
 
-  HdNode = (HARDDRIVE_DEVICE_PATH *)(
-                                     FindDevicePathNodeWithType (
-                                       HdDevicePath,
-                                       MEDIA_DEVICE_PATH,
-                                       MEDIA_HARDDRIVE_DP
-                                       )
-                                     );
+  HdNode = FindDevicePathNodeWithType (
+             HdDevicePath,
+             MEDIA_DEVICE_PATH,
+             MEDIA_HARDDRIVE_DP
+             );
   if (HdNode == NULL) {
-    return NULL;
+    HdNode = FindDevicePathNodeWithType (
+               HdDevicePath,
+               MEDIA_DEVICE_PATH,
+               MEDIA_CDROM_DP
+               );
+    if (HdNode == NULL) {
+      return NULL;
+    }
+
+    DEBUG ((DEBUG_INFO, "got cdrom\n"));
   }
 
   PrefixPath = DuplicateDevicePath (HdDevicePath);
@@ -298,6 +305,29 @@ OcPartitionGetDiskHandle (
            );
 }
 
+BOOLEAN
+OcIsDiskCdRom (
+  IN EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath
+  )
+{
+  EFI_DEVICE_PATH_PROTOCOL  *DevicePathWalker;
+
+  ASSERT (DiskDevicePath != NULL);
+
+  DevicePathWalker = DiskDevicePath;
+  while (!IsDevicePathEnd (DevicePathWalker)) {
+    if (  (DevicePathType (DevicePathWalker) == MEDIA_DEVICE_PATH)
+       && (DevicePathSubType (DevicePathWalker) == MEDIA_CDROM_DP))
+    {
+      return TRUE;
+    }
+
+    DevicePathWalker = NextDevicePathNode (DevicePathWalker);
+  }
+
+  return FALSE;
+}
+
 EFI_DEVICE_PATH_PROTOCOL *
 OcDiskFindSystemPartitionPath (
   IN  CONST EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
@@ -676,6 +706,7 @@ OcGetDiskMbrTable (
 {
   EFI_STATUS          Status;
   MASTER_BOOT_RECORD  *Mbr;
+  UINTN               MbrSize;
   OC_DISK_CONTEXT     DiskContext;
   UINTN               Index;
   BOOLEAN             IsProtectiveMbr;
@@ -685,17 +716,27 @@ OcGetDiskMbrTable (
   //
   // Read first sector containing MBR table.
   //
-  Status = OcDiskInitializeContext (&DiskContext, DiskHandle, UseBlockIo2);
+  Status = OcDiskInitializeContext (
+             &DiskContext,
+             DiskHandle,
+             UseBlockIo2
+             );
   if (EFI_ERROR (Status)) {
     return NULL;
   }
 
-  Mbr = (MASTER_BOOT_RECORD *)AllocatePool (sizeof (*Mbr));
+  MbrSize = ALIGN_VALUE (sizeof (*Mbr), DiskContext.BlockSize);
+  Mbr     = (MASTER_BOOT_RECORD *)AllocatePool (MbrSize);
   if (Mbr == NULL) {
     return NULL;
   }
 
-  Status = OcDiskRead (&DiskContext, 0, sizeof (*Mbr), Mbr);
+  Status = OcDiskRead (
+             &DiskContext,
+             0,
+             MbrSize,
+             Mbr
+             );
   if (EFI_ERROR (Status)) {
     FreePool (Mbr);
     return NULL;

From 0a92019b1217e099f751193026f726c8b87ed266 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 7 Aug 2023 18:14:57 -0500
Subject: [PATCH 16/55] OcBootManagementLib: Only attempt Apple legacy boot
 when available

---
 Library/OcBootManagementLib/DefaultEntryChoice.c | 15 ++++++++++-----
 Library/OcBootManagementLib/LegacyBootSupport.c  |  1 -
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/Library/OcBootManagementLib/DefaultEntryChoice.c b/Library/OcBootManagementLib/DefaultEntryChoice.c
index cfcb851cc72..52937a7217f 100644
--- a/Library/OcBootManagementLib/DefaultEntryChoice.c
+++ b/Library/OcBootManagementLib/DefaultEntryChoice.c
@@ -1578,11 +1578,16 @@ InternalLoadBootEntry (
   DEBUG_CODE_END ();
 
   if (BootEntry->LegacyOsType != OcLegacyOsTypeNone) {
-    Status = InternalLoadAppleLegacyInterface (
-               ParentHandle,
-               DevicePath,
-               EntryHandle
-               );
+    if (Context->LegacyBootType == OcLegacyBootTypeApple) {
+      Status = InternalLoadAppleLegacyInterface (
+                 ParentHandle,
+                 DevicePath,
+                 EntryHandle
+                 );
+    } else {
+      DEBUG ((DEBUG_INFO, "OCB: Unsupported legacy interface type: %u\n", Context->LegacyBootType));
+      Status = EFI_UNSUPPORTED;
+    }
   } else {
     Status = gBS->LoadImage (
                     FALSE,
diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index fc4ffeeb6e4..2c053403ffb 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -171,7 +171,6 @@ InternalLoadAppleLegacyInterface (
 
   //
   // Get device path to disk to be booted.
-  // TODO: Handle CD booting, device path is not required in that case.
   //
   if (!OcIsDiskCdRom (HdDevicePath)) {
     WholeDiskPath = OcDiskGetDevicePath (HdDevicePath);

From 3b6d8b8c98635ee5eecf7300ae227c29f340cc81 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 7 Aug 2023 18:15:47 -0500
Subject: [PATCH 17/55] OcBootManagementLib: Move legacy type detection into
 library

---
 .../Acidanthera/Library/OcBootManagementLib.h |  3 +-
 .../BootManagementInternal.h                  |  5 +++
 .../OcBootManagementLib/LegacyBootSupport.c   | 31 +++++++++++++++++--
 .../OcBootManagementLib/OcBootManagementLib.c |  5 +++
 .../OcBootManagementLib.inf                   |  2 ++
 Library/OcMainLib/OpenCoreMisc.c              |  8 -----
 6 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index 4966683133b..10fcc44e92e 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -158,7 +158,8 @@ typedef UINT32 OC_BOOT_ENTRY_TYPE;
 **/
 typedef enum OC_LEGACY_BOOT_TYPE_ {
   OcLegacyBootTypeNone,
-  OcLegacyBootTypeApple
+  OcLegacyBootTypeApple,
+  OcLegacyBootTypeLegacyBios
 } OC_LEGACY_BOOT_TYPE;
 
 /**
diff --git a/Library/OcBootManagementLib/BootManagementInternal.h b/Library/OcBootManagementLib/BootManagementInternal.h
index 038e96bcecc..2d3e0ba6f6d 100644
--- a/Library/OcBootManagementLib/BootManagementInternal.h
+++ b/Library/OcBootManagementLib/BootManagementInternal.h
@@ -136,6 +136,11 @@ InternalGetPartitionLegacyOsType (
   IN  EFI_HANDLE  PartitionHandle
   );
 
+OC_LEGACY_BOOT_TYPE
+InternalGetLegacyBootType (
+  VOID
+  );
+
 EFI_STATUS
 InternalCheckScanPolicy (
   IN  EFI_HANDLE  Handle,
diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Library/OcBootManagementLib/LegacyBootSupport.c
index 2c053403ffb..985fc620a74 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Library/OcBootManagementLib/LegacyBootSupport.c
@@ -16,8 +16,6 @@
 
 #include <IndustryStandard/Mbr.h>
 
-#include <Protocol/DevicePath.h>
-
 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
 #include <Library/DevicePathLib.h>
@@ -31,6 +29,9 @@
 #include <Library/UefiLib.h>
 #include <Library/UefiRuntimeServicesTableLib.h>
 
+#include <Protocol/DevicePath.h>
+#include <Protocol/Legacy8259.h>
+
 //
 // PIWG firmware media device path for Apple legacy interface.
 // FwFile(2B0585EB-D8B8-49A9-8B8CE21B01AEF2B7)
@@ -349,3 +350,29 @@ InternalGetPartitionLegacyOsType (
 
   return LegacyOsType;
 }
+
+OC_LEGACY_BOOT_TYPE
+InternalGetLegacyBootType (
+  VOID
+  )
+{
+  EFI_STATUS                Status;
+  EFI_LEGACY_8259_PROTOCOL  *Legacy8259;
+  OC_LEGACY_BOOT_TYPE       BootType;
+
+  //
+  // Apple legacy boot interface is only available on Apple platforms.
+  // Use legacy 16-bit thunks on legacy PC platforms.
+  //
+  BootType = OcLegacyBootTypeNone;
+  if (OcStriCmp (L"Apple", gST->FirmwareVendor) == 0) {
+    BootType = OcLegacyBootTypeApple;
+  } else {
+    Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **)&Legacy8259);
+    if (!EFI_ERROR (Status) && (Legacy8259 != NULL)) {
+      BootType = OcLegacyBootTypeLegacyBios;
+    }
+  }
+
+  return BootType;
+}
diff --git a/Library/OcBootManagementLib/OcBootManagementLib.c b/Library/OcBootManagementLib/OcBootManagementLib.c
index b1d778226fa..85963549bb2 100644
--- a/Library/OcBootManagementLib/OcBootManagementLib.c
+++ b/Library/OcBootManagementLib/OcBootManagementLib.c
@@ -324,6 +324,11 @@ OcRunBootPicker (
     Context->HideAuxiliary = FALSE;
   }
 
+  //
+  // Get legacy boot mode.
+  //
+  Context->LegacyBootType = InternalGetLegacyBootType ();
+
   while (TRUE) {
     //
     // Never show Apple Picker twice, re-scan for entries if we previously successfully showed it.
diff --git a/Library/OcBootManagementLib/OcBootManagementLib.inf b/Library/OcBootManagementLib/OcBootManagementLib.inf
index 02b44687c72..42efff2e8e2 100644
--- a/Library/OcBootManagementLib/OcBootManagementLib.inf
+++ b/Library/OcBootManagementLib/OcBootManagementLib.inf
@@ -53,6 +53,7 @@
   OpenCorePkg/OpenCorePkg.dec
   MdePkg/MdePkg.dec
   MdeModulePkg/MdeModulePkg.dec
+  OvmfPkg/OvmfPkg.dec
   UefiCpuPkg/UefiCpuPkg.dec
 
 [Guids]
@@ -85,6 +86,7 @@
   gAppleBeepGenProtocolGuid                     ## SOMETIMES_CONSUMES
   gOcBootEntryProtocolGuid                      ## CONSUMES
   gAppleFirmwareUserInterfaceProtocolGuid       ## SOMETIMES_CONSUMES
+  gEfiLegacy8259ProtocolGuid                    ## SOMETIMES_CONSUMES
 
 [LibraryClasses]
   BaseLib
diff --git a/Library/OcMainLib/OpenCoreMisc.c b/Library/OcMainLib/OpenCoreMisc.c
index b2277b58385..29fb6229e67 100644
--- a/Library/OcMainLib/OpenCoreMisc.c
+++ b/Library/OcMainLib/OpenCoreMisc.c
@@ -939,14 +939,6 @@ OcMiscBoot (
   Context->InstanceIdentifier   = AsciiInstanceIdentifier;
   Context->BlacklistAppleUpdate = Config->Misc.Security.BlacklistAppleUpdate;
 
-  //
-  // Apple legacy boot interface is only available on Apple platforms.
-  //
-  Context->LegacyBootType = OcLegacyBootTypeNone;
-  if (OcStriCmp (L"Apple", gST->FirmwareVendor) == 0) {
-    Context->LegacyBootType = OcLegacyBootTypeApple;
-  }
-
   if ((Config->Misc.Security.ExposeSensitiveData & OCS_EXPOSE_VERSION_UI) != 0) {
     Context->TitleSuffix = OcMiscGetVersionString ();
   }

From c9abfdaefe5bbe9d804df7e3bf7e74a1faf899b5 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 7 Aug 2023 19:42:41 -0500
Subject: [PATCH 18/55] OcLegacyThunkLib: Consolidate 16-bit thunking interface
 into library

---
 .../Acidanthera/Library/OcLegacyThunkLib.h    |  70 ++++++
 Legacy/BootPlatform/BiosVideo/BiosVideo.c     |  26 +--
 Legacy/BootPlatform/BiosVideo/BiosVideo.h     |  57 +----
 Legacy/BootPlatform/BiosVideo/BiosVideo.inf   |   2 +-
 Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c    |   4 +-
 Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.h    |  49 +---
 Legacy/BootPlatform/BlockIoDxe/BiosInt13.c    |  24 +-
 Legacy/BootPlatform/BlockIoDxe/BlockIoDxe.inf |   2 +-
 .../BootPlatform/BlockIoDxe/LegacyBiosThunk.c | 216 ------------------
 Legacy/BootPlatform/CpuDxe/CpuDxe.c           | 138 +----------
 Legacy/BootPlatform/CpuDxe/CpuDxe.h           |   8 +-
 Legacy/BootPlatform/CpuDxe/CpuDxe.inf         |   2 +
 .../OcLegacyThunkLib/OcLegacyThunkLib.c       |  47 ++--
 Library/OcLegacyThunkLib/OcLegacyThunkLib.inf |  49 ++++
 OpenCorePkg.dec                               |   3 +
 OpenCorePkg.dsc                               |   1 +
 OpenDuetPkg.dsc                               |   1 +
 17 files changed, 189 insertions(+), 510 deletions(-)
 create mode 100644 Include/Acidanthera/Library/OcLegacyThunkLib.h
 delete mode 100644 Legacy/BootPlatform/BlockIoDxe/LegacyBiosThunk.c
 rename Legacy/BootPlatform/BiosVideo/LegacyBiosThunk.c => Library/OcLegacyThunkLib/OcLegacyThunkLib.c (83%)
 create mode 100644 Library/OcLegacyThunkLib/OcLegacyThunkLib.inf

diff --git a/Include/Acidanthera/Library/OcLegacyThunkLib.h b/Include/Acidanthera/Library/OcLegacyThunkLib.h
new file mode 100644
index 00000000000..4c2a97c3056
--- /dev/null
+++ b/Include/Acidanthera/Library/OcLegacyThunkLib.h
@@ -0,0 +1,70 @@
+/** @file
+  This library implements thunking to legacy 16-bit environment.
+
+  Copyright (c) 2023, Goldfish64. All rights reserved.<BR>
+  Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause
+**/
+
+#ifndef OC_LEGACY_THUNK_LIB_H
+#define OC_LEGACY_THUNK_LIB_H
+
+#include <Protocol/Legacy8259.h>
+
+//
+// Legacy region base is 0x0C0000.
+//
+#define LEGACY_REGION_BASE  0x0C0000
+#define LEGACY_REGION_SIZE  0x10000
+
+#define EFI_SEGMENT(_Adr)  (UINT16) ((UINT16) (((UINTN) (_Adr)) >> 4) & 0xf000)
+#define EFI_OFFSET(_Adr)   (UINT16) (((UINT16) ((UINTN) (_Adr))) & 0xffff)
+
+/**
+  Initialize legacy environment for BIOS INI caller.
+
+  @param ThunkContext   the instance pointer of THUNK_CONTEXT
+**/
+VOID
+OcLegacyThunkInitializeBiosIntCaller (
+  IN OUT THUNK_CONTEXT  *ThunkContext
+  );
+
+/**
+   Initialize interrupt redirection code and entries, because
+   IDT Vectors 0x68-0x6f must be redirected to IDT Vectors 0x08-0x0f.
+   Or the interrupt will lost when we do thunk.
+   NOTE: We do not reset 8259 vector base, because it will cause pending
+   interrupt lost.
+
+   @param Legacy8259  Instance pointer for EFI_LEGACY_8259_PROTOCOL.
+
+**/
+VOID
+OcLegacyThunkInitializeInterruptRedirection (
+  IN EFI_LEGACY_8259_PROTOCOL  *Legacy8259
+  );
+
+/**
+  Thunk to 16-bit real mode and execute a software interrupt with a vector
+  of BiosInt. Regs will contain the 16-bit register context on entry and
+  exit.
+
+  @param  This    Protocol instance pointer.
+  @param  BiosInt Processor interrupt vector to invoke
+  @param  Reg     Register contexted passed into (and returned) from thunk to 16-bit mode
+
+  @retval TRUE   Thunk completed, and there were no BIOS errors in the target code.
+                 See Regs for status.
+  @retval FALSE  There was a BIOS erro in the target code.
+**/
+BOOLEAN
+EFIAPI
+OcLegacyThunkBiosInt86 (
+  IN  THUNK_CONTEXT             *ThunkContext,
+  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN  UINT8                     BiosInt,
+  IN  IA32_REGISTER_SET         *Regs
+  );
+
+#endif // OC_LEGACY_THUNK_LIB_H
diff --git a/Legacy/BootPlatform/BiosVideo/BiosVideo.c b/Legacy/BootPlatform/BiosVideo/BiosVideo.c
index f977eee14a7..010c5f625b1 100644
--- a/Legacy/BootPlatform/BiosVideo/BiosVideo.c
+++ b/Legacy/BootPlatform/BiosVideo/BiosVideo.c
@@ -209,8 +209,8 @@ BiosVideoDriverBindingStart (
       goto Done;
     }
 
-    InitializeBiosIntCaller (&mThunkContext);
-    InitializeInterruptRedirection (mLegacy8259);
+    OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
+    OcLegacyThunkInitializeInterruptRedirection (mLegacy8259);
   }
 
   //
@@ -622,12 +622,12 @@ BiosVideoChildHandleUninstall (
   //
   Regs.H.AH = 0x00;
   Regs.H.AL = 0x03;
-  LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+  OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
   Regs.H.AH = 0x11;
   Regs.H.AL = 0x14;
   Regs.H.BL = 0;
-  LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+  OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
   //
   // Do not disable IO/memory decode since that would prevent legacy ROM from working
@@ -712,7 +712,7 @@ BiosVideoGetVbeData (
   Regs.E.ES                                            = EFI_SEGMENT ((UINTN)BiosVideoPrivate->VbeInformationBlock);
   Regs.X.DI                                            = EFI_OFFSET ((UINTN)BiosVideoPrivate->VbeInformationBlock);
 
-  LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+  OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
   Status = EFI_DEVICE_ERROR;
 
@@ -772,7 +772,7 @@ BiosVideoGetVbeData (
     Regs.E.ES = EFI_SEGMENT ((UINTN)BiosVideoPrivate->VbeModeInformationBlock);
     Regs.X.DI = EFI_OFFSET ((UINTN)BiosVideoPrivate->VbeModeInformationBlock);
 
-    LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+    OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
     //
     // See if the call succeeded.  If it didn't, then try the next mode.
@@ -984,7 +984,7 @@ BiosVideoGetVbeData (
   Regs.E.ES = EFI_SEGMENT ((UINTN)BiosVideoPrivate->VbeEdidDataBlock);
   Regs.X.DI = EFI_OFFSET ((UINTN)BiosVideoPrivate->VbeEdidDataBlock);
 
-  LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+  OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
   //
   // If the call succeed, populate EDID Discovered protocol.
@@ -1533,7 +1533,7 @@ BiosVideoSetModeWorker (
     // Set VGA Mode
     //
     Regs.X.AX = ModeData->VbeModeNumber;
-    LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+    OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
   } else {
     //
     // Allocate a working buffer for BLT operations to the VBE frame buffer
@@ -1554,7 +1554,7 @@ BiosVideoSetModeWorker (
     Regs.E.ES = EFI_SEGMENT ((UINTN)BiosVideoPrivate->VbeCrtcInformationBlock);
     Regs.X.DI = EFI_OFFSET ((UINTN)BiosVideoPrivate->VbeCrtcInformationBlock);
 
-    LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+    OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
     //
     // Check to see if the call succeeded
@@ -2652,12 +2652,12 @@ BiosVideoVgaMiniPortSetMode (
       //
       Regs.H.AH = 0x00;
       Regs.H.AL = 0x83;
-      LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+      OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
       Regs.H.AH = 0x11;
       Regs.H.AL = 0x14;
       Regs.H.BL = 0;
-      LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+      OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
       break;
 
@@ -2667,12 +2667,12 @@ BiosVideoVgaMiniPortSetMode (
       //
       Regs.H.AH = 0x00;
       Regs.H.AL = 0x83;
-      LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+      OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
 
       Regs.H.AH = 0x11;
       Regs.H.AL = 0x12;
       Regs.H.BL = 0;
-      LegacyBiosInt86 (BiosVideoPrivate, 0x10, &Regs);
+      OcLegacyThunkBiosInt86 (BiosVideoPrivate->ThunkContext, BiosVideoPrivate->Legacy8259, 0x10, &Regs);
       break;
 
     default:
diff --git a/Legacy/BootPlatform/BiosVideo/BiosVideo.h b/Legacy/BootPlatform/BiosVideo/BiosVideo.h
index c6a886635d4..aec22985c30 100644
--- a/Legacy/BootPlatform/BiosVideo/BiosVideo.h
+++ b/Legacy/BootPlatform/BiosVideo/BiosVideo.h
@@ -47,6 +47,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #include <Library/MemoryAllocationLib.h>
 #include <Library/DevicePathLib.h>
 
+#include <Library/OcLegacyThunkLib.h>
 #include <Library/OcMemoryLib.h>
 #include <Library/OcMiscLib.h>
 
@@ -55,13 +56,6 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 #include "VesaBiosExtensions.h"
 
-//
-// ** CHANGE **
-// Legacy region base is now 0x0C0000 instead of 0x100000.
-//
-#define LEGACY_REGION_BASE  0x0C0000
-#define LEGACY_REGION_SIZE  0x10000
-
 //
 // Vendor IDs.
 //
@@ -171,9 +165,6 @@ typedef struct {
 
 #define GRAPHICS_OUTPUT_INVALIDE_MODE_NUMBER  0xffff
 
-#define EFI_SEGMENT(_Adr)  (UINT16) ((UINT16) (((UINTN) (_Adr)) >> 4) & 0xf000)
-#define EFI_OFFSET(_Adr)   (UINT16) (((UINT16) ((UINTN) (_Adr))) & 0xffff)
-
 //
 // Global Variables
 //
@@ -553,52 +544,6 @@ BiosVideoIsVga (
 
 #define VGA_GRAPHICS_CONTROLLER_BIT_MASK_REGISTER  0x08
 
-/**
-  Initialize legacy environment for BIOS INI caller.
-
-  @param ThunkContext   the instance pointer of THUNK_CONTEXT
-**/
-VOID
-InitializeBiosIntCaller (
-  THUNK_CONTEXT  *ThunkContext
-  );
-
-/**
-   Initialize interrupt redirection code and entries, because
-   IDT Vectors 0x68-0x6f must be redirected to IDT Vectors 0x08-0x0f.
-   Or the interrupt will lost when we do thunk.
-   NOTE: We do not reset 8259 vector base, because it will cause pending
-   interrupt lost.
-
-   @param Legacy8259  Instance pointer for EFI_LEGACY_8259_PROTOCOL.
-
-**/
-VOID
-InitializeInterruptRedirection (
-  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259
-  );
-
-/**
-  Thunk to 16-bit real mode and execute a software interrupt with a vector
-  of BiosInt. Regs will contain the 16-bit register context on entry and
-  exit.
-
-  @param  This    Protocol instance pointer.
-  @param  BiosInt Processor interrupt vector to invoke
-  @param  Reg     Register contexted passed into (and returned) from thunk to 16-bit mode
-
-  @retval TRUE   Thunk completed, and there were no BIOS errors in the target code.
-                 See Regs for status.
-  @retval FALSE  There was a BIOS erro in the target code.
-**/
-BOOLEAN
-EFIAPI
-LegacyBiosInt86 (
-  IN  BIOS_VIDEO_DEV     *BiosDev,
-  IN  UINT8              BiosInt,
-  IN  IA32_REGISTER_SET  *Regs
-  );
-
 /**
   Force the specified resolution and reconnect the controller.
   Specifying zero for Width and Height will pull the maximum
diff --git a/Legacy/BootPlatform/BiosVideo/BiosVideo.inf b/Legacy/BootPlatform/BiosVideo/BiosVideo.inf
index 23a88534cb0..52ce22c6b74 100644
--- a/Legacy/BootPlatform/BiosVideo/BiosVideo.inf
+++ b/Legacy/BootPlatform/BiosVideo/BiosVideo.inf
@@ -37,6 +37,7 @@
   MemoryAllocationLib
   UefiDriverEntryPoint
   DevicePathLib
+  OcLegacyThunkLib
   OcMemoryLib
   OcMiscLib
 
@@ -45,7 +46,6 @@
   BiosVideo.c
   ComponentName.c
   VesaBiosExtensions.h
-  LegacyBiosThunk.c
   VideoBiosPatch.c
 
 [Protocols]
diff --git a/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c b/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c
index 5daecf12895..a6598f951ae 100644
--- a/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c
+++ b/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c
@@ -255,8 +255,8 @@ BiosBlockIoDriverBindingStart (
     goto Error;
   }
 
-  InitializeBiosIntCaller (&mThunkContext);
-  InitializeInterruptRedirection (Legacy8259);
+  OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
+  OcLegacyThunkInitializeInterruptRedirection (Legacy8259);
 
   //
   // Open the IO Abstraction(s) needed
diff --git a/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.h b/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.h
index b8bb04ea669..c971e597668 100644
--- a/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.h
+++ b/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.h
@@ -26,13 +26,12 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 #include <Library/UefiLib.h>
 #include <Library/DevicePathLib.h>
 #include <Library/MemoryAllocationLib.h>
+#include <Library/OcLegacyThunkLib.h>
 
 #include <IndustryStandard/Pci.h>
 
 #include "Edd.h"
 
-#define LEGACY_REGION_BASE  0x0C0000
-
 //
 // Global Variables
 //
@@ -423,50 +422,4 @@ SetBiosInitBlockIoDevicePath (
   OUT EFI_DEVICE_PATH_PROTOCOL  **DevicePath
   );
 
-/**
-  Initialize legacy environment for BIOS INI caller.
-
-  @param ThunkContext   the instance pointer of THUNK_CONTEXT
-**/
-VOID
-InitializeBiosIntCaller (
-  THUNK_CONTEXT  *ThunkContext
-  );
-
-/**
-   Initialize interrupt redirection code and entries, because
-   IDT Vectors 0x68-0x6f must be redirected to IDT Vectors 0x08-0x0f.
-   Or the interrupt will lost when we do thunk.
-   NOTE: We do not reset 8259 vector base, because it will cause pending
-   interrupt lost.
-
-   @param Legacy8259  Instance pointer for EFI_LEGACY_8259_PROTOCOL.
-
-**/
-VOID
-InitializeInterruptRedirection (
-  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259
-  );
-
-/**
-  Thunk to 16-bit real mode and execute a software interrupt with a vector
-  of BiosInt. Regs will contain the 16-bit register context on entry and
-  exit.
-
-  @param  This    Protocol instance pointer.
-  @param  BiosInt Processor interrupt vector to invoke
-  @param  Reg     Register contexted passed into (and returned) from thunk to 16-bit mode
-
-  @retval TRUE   Thunk completed, and there were no BIOS errors in the target code.
-                 See Regs for status.
-  @retval FALSE  There was a BIOS erro in the target code.
-**/
-BOOLEAN
-EFIAPI
-LegacyBiosInt86 (
-  IN  BIOS_BLOCK_IO_DEV  *BiosDev,
-  IN  UINT8              BiosInt,
-  IN  IA32_REGISTER_SET  *Regs
-  );
-
 #endif
diff --git a/Legacy/BootPlatform/BlockIoDxe/BiosInt13.c b/Legacy/BootPlatform/BlockIoDxe/BiosInt13.c
index 7b8c8765a74..d6c0c686909 100644
--- a/Legacy/BootPlatform/BlockIoDxe/BiosInt13.c
+++ b/Legacy/BootPlatform/BlockIoDxe/BiosInt13.c
@@ -137,7 +137,7 @@ Int13GetDeviceParameters (
 
   Regs.H.AH = 0x08;
   Regs.H.DL = Drive->Number;
-  CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+  CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
   DEBUG ((DEBUG_INIT, "Int13GetDeviceParameters: INT 13 08 DL=%02x : CF=%d AH=%02x\n", Drive->Number, CarryFlag, Regs.H.AH));
   if ((CarryFlag != 0) || (Regs.H.AH != 0x00)) {
     Drive->ErrorCode = Regs.H.AH;
@@ -192,7 +192,7 @@ Int13Extensions (
   Regs.H.AH = 0x41;
   Regs.X.BX = 0x55aa;
   Regs.H.DL = Drive->Number;
-  CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+  CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
   DEBUG ((DEBUG_INIT, "Int13Extensions: INT 13 41 DL=%02x : CF=%d BX=%04x\n", Drive->Number, CarryFlag, Regs.X.BX));
 
   if ((CarryFlag != 0) || (Regs.X.BX != 0xaa55)) {
@@ -242,7 +242,7 @@ GetDriveParameters (
   mLegacyDriverUnder1Mb->Parameters.StructureSize = (UINT16)sizeof (EDD_DRIVE_PARAMETERS);
   Regs.E.DS                                       = EFI_SEGMENT ((UINTN)(&mLegacyDriverUnder1Mb->Parameters));
   Regs.X.SI                                       = EFI_OFFSET ((UINTN)(&mLegacyDriverUnder1Mb->Parameters));
-  CarryFlag                                       = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+  CarryFlag                                       = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
   DEBUG ((DEBUG_INIT, "GetDriveParameters: INT 13 48 DL=%02x : CF=%d AH=%02x\n", Drive->Number, CarryFlag, Regs.H.AH));
   if ((CarryFlag != 0) || (Regs.H.AH != 0x00)) {
     Drive->ErrorCode = Regs.H.AH;
@@ -265,7 +265,7 @@ GetDriveParameters (
     //
     Regs.H.AH = 0x20;
     Regs.H.DL = Drive->Number;
-    CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+    CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
     DEBUG ((DEBUG_INIT, "GetDriveParameters: INT 13 20 DL=%02x : CF=%d AL=%02x\n", Drive->Number, CarryFlag, Regs.H.AL));
     if (CarryFlag != 0) {
       //
@@ -482,7 +482,7 @@ Edd30BiosReadBlocks (
     Regs.X.SI = EFI_OFFSET (AddressPacket);
     Regs.E.DS = EFI_SEGMENT (AddressPacket);
 
-    CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+    CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
     DEBUG (
       (
        DEBUG_BLKIO, "Edd30BiosReadBlocks: INT 13 42 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number,
@@ -631,7 +631,7 @@ Edd30BiosWriteBlocks (
     Regs.X.SI = EFI_OFFSET (AddressPacket);
     Regs.E.DS = EFI_SEGMENT (AddressPacket);
 
-    CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+    CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
     DEBUG (
       (
        DEBUG_BLKIO, "Edd30BiosWriteBlocks: INT 13 43 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number,
@@ -730,7 +730,7 @@ BiosBlockIoReset (
 
   Regs.H.AH = 0x00;
   Regs.H.DL = BiosBlockIoDev->Bios.Number;
-  CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+  CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
   DEBUG (
     (
      DEBUG_INIT, "BiosBlockIoReset: INT 13 00 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number, CarryFlag,
@@ -742,7 +742,7 @@ BiosBlockIoReset (
     if (Regs.H.AL == BIOS_RESET_FAILED) {
       Regs.H.AH = 0x00;
       Regs.H.DL = BiosBlockIoDev->Bios.Number;
-      CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+      CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
       DEBUG (
         (
          DEBUG_INIT, "BiosBlockIoReset: INT 13 00 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number, CarryFlag,
@@ -867,7 +867,7 @@ Edd11BiosReadBlocks (
     Regs.X.SI = EFI_OFFSET (AddressPacket);
     Regs.E.DS = EFI_SEGMENT (AddressPacket);
 
-    CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+    CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
     DEBUG (
       (
        DEBUG_BLKIO, "Edd11BiosReadBlocks: INT 13 42 DL=%02x : CF=%d AH=%02x : LBA 0x%lx  Block(s) %0d \n",
@@ -1025,7 +1025,7 @@ Edd11BiosWriteBlocks (
     TransferByteSize = NumberOfBlocks * BlockSize;
     CopyMem ((VOID *)(UINTN)TransferBuffer, Buffer, TransferByteSize);
 
-    CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+    CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
     DEBUG (
       (
        DEBUG_BLKIO, "Edd11BiosWriteBlocks: INT 13 43 DL=%02x : CF=%d AH=%02x\n: LBA 0x%lx  Block(s) %0d \n",
@@ -1217,7 +1217,7 @@ BiosReadLegacyDrive (
          EFI_SEGMENT (mEdd11Buffer))
         );
 
-      CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+      CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
       DEBUG (
         (
          DEBUG_BLKIO, "BiosReadLegacyDrive: INT 13 02 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number,
@@ -1422,7 +1422,7 @@ BiosWriteLegacyDrive (
          EFI_SEGMENT (mEdd11Buffer))
         );
 
-      CarryFlag = LegacyBiosInt86 (BiosBlockIoDev, 0x13, &Regs);
+      CarryFlag = OcLegacyThunkBiosInt86 (BiosBlockIoDev->ThunkContext, BiosBlockIoDev->Legacy8259, 0x13, &Regs);
       DEBUG (
         (
          DEBUG_BLKIO, "BiosWriteLegacyDrive: INT 13 03 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number,
diff --git a/Legacy/BootPlatform/BlockIoDxe/BlockIoDxe.inf b/Legacy/BootPlatform/BlockIoDxe/BlockIoDxe.inf
index f02cd734db1..7a732a93ee2 100644
--- a/Legacy/BootPlatform/BlockIoDxe/BlockIoDxe.inf
+++ b/Legacy/BootPlatform/BlockIoDxe/BlockIoDxe.inf
@@ -26,7 +26,6 @@
   BiosBlkIo.c
   BiosInt13.c
   ComponentName.c
-  LegacyBiosThunk.c
 
 [LibraryClasses]
   UefiDriverEntryPoint
@@ -36,6 +35,7 @@
   UefiLib
   DevicePathLib
   MemoryAllocationLib
+  OcLegacyThunkLib
 
 [Protocols]
   gEfiBlockIoProtocolGuid    ## BY_START
diff --git a/Legacy/BootPlatform/BlockIoDxe/LegacyBiosThunk.c b/Legacy/BootPlatform/BlockIoDxe/LegacyBiosThunk.c
deleted file mode 100644
index e0e426a739e..00000000000
--- a/Legacy/BootPlatform/BlockIoDxe/LegacyBiosThunk.c
+++ /dev/null
@@ -1,216 +0,0 @@
-/** @file
-  Provide legacy thunk interface for accessing Bios Block I/O.
-
-Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>
-This program and the accompanying materials
-are licensed and made available under the terms and conditions of the BSD License
-which accompanies this distribution.  The full text of the license may be found at
-http://opensource.org/licenses/bsd-license.php
-
-THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
-WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
-
-**/
-
-#include "BiosBlkIo.h"
-
-/**
-  Initialize legacy environment for BIOS INI caller.
-
-  @param ThunkContext   the instance pointer of THUNK_CONTEXT
-**/
-VOID
-InitializeBiosIntCaller (
-  THUNK_CONTEXT  *ThunkContext
-  )
-{
-  EFI_STATUS            Status;
-  UINT32                RealModeBufferSize;
-  UINT32                ExtraStackSize;
-  EFI_PHYSICAL_ADDRESS  LegacyRegionBase;
-  UINT32                LegacyRegionSize;
-
-  //
-  // Get LegacyRegion
-  //
-  AsmGetThunk16Properties (&RealModeBufferSize, &ExtraStackSize);
-  LegacyRegionSize = (((RealModeBufferSize + ExtraStackSize) / EFI_PAGE_SIZE) + 1) * EFI_PAGE_SIZE;
-  LegacyRegionBase = LEGACY_REGION_BASE;
-  Status           = gBS->AllocatePages (
-                            AllocateMaxAddress,
-                            EfiACPIMemoryNVS,
-                            EFI_SIZE_TO_PAGES (LegacyRegionSize),
-                            &LegacyRegionBase
-                            );
-  ASSERT_EFI_ERROR (Status);
-
-  ThunkContext->RealModeBuffer     = (VOID *)(UINTN)LegacyRegionBase;
-  ThunkContext->RealModeBufferSize = LegacyRegionSize;
-  ThunkContext->ThunkAttributes    = THUNK_ATTRIBUTE_BIG_REAL_MODE|THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15;
-  AsmPrepareThunk16 (ThunkContext);
-}
-
-/**
-   Initialize interrupt redirection code and entries, because
-   IDT Vectors 0x68-0x6f must be redirected to IDT Vectors 0x08-0x0f.
-   Or the interrupt will lost when we do thunk.
-   NOTE: We do not reset 8259 vector base, because it will cause pending
-   interrupt lost.
-
-   @param Legacy8259  Instance pointer for EFI_LEGACY_8259_PROTOCOL.
-
-**/
-VOID
-InitializeInterruptRedirection (
-  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259
-  )
-{
-  EFI_STATUS            Status;
-  EFI_PHYSICAL_ADDRESS  LegacyRegionBase;
-  UINTN                 LegacyRegionLength;
-  volatile UINT32       *IdtArray;
-  UINTN                 Index;
-  UINT8                 ProtectedModeBaseVector;
-
-  STATIC CONST UINT32  InterruptRedirectionCode[] = {
-    0x90CF08CD, // INT8; IRET; NOP
-    0x90CF09CD, // INT9; IRET; NOP
-    0x90CF0ACD, // INTA; IRET; NOP
-    0x90CF0BCD, // INTB; IRET; NOP
-    0x90CF0CCD, // INTC; IRET; NOP
-    0x90CF0DCD, // INTD; IRET; NOP
-    0x90CF0ECD, // INTE; IRET; NOP
-    0x90CF0FCD  // INTF; IRET; NOP
-  };
-
-  //
-  // Get LegacyRegion
-  //
-  LegacyRegionLength = sizeof (InterruptRedirectionCode);
-  LegacyRegionBase   = LEGACY_REGION_BASE;
-  Status             = gBS->AllocatePages (
-                              AllocateMaxAddress,
-                              EfiACPIMemoryNVS,
-                              EFI_SIZE_TO_PAGES (LegacyRegionLength),
-                              &LegacyRegionBase
-                              );
-  ASSERT_EFI_ERROR (Status);
-
-  //
-  // Copy code to legacy region
-  //
-  CopyMem ((VOID *)(UINTN)LegacyRegionBase, InterruptRedirectionCode, sizeof (InterruptRedirectionCode));
-
-  //
-  // Get VectorBase, it should be 0x68
-  //
-  Status = Legacy8259->GetVector (Legacy8259, Efi8259Irq0, &ProtectedModeBaseVector);
-  ASSERT_EFI_ERROR (Status);
-
-  //
-  // Patch IVT 0x68 ~ 0x6f
-  //
-  IdtArray = (UINT32 *)0;
-  for (Index = 0; Index < 8; Index++) {
-    IdtArray[ProtectedModeBaseVector + Index] = ((EFI_SEGMENT (LegacyRegionBase + Index * 4)) << 16) | (EFI_OFFSET (LegacyRegionBase + Index * 4));
-  }
-}
-
-/**
-  Thunk to 16-bit real mode and execute a software interrupt with a vector
-  of BiosInt. Regs will contain the 16-bit register context on entry and
-  exit.
-
-  @param  This    Protocol instance pointer.
-  @param  BiosInt Processor interrupt vector to invoke
-  @param  Reg     Register contexted passed into (and returned) from thunk to 16-bit mode
-
-  @retval TRUE   Thunk completed, and there were no BIOS errors in the target code.
-                 See Regs for status.
-  @retval FALSE  There was a BIOS erro in the target code.
-**/
-BOOLEAN
-EFIAPI
-LegacyBiosInt86 (
-  IN  BIOS_BLOCK_IO_DEV  *BiosDev,
-  IN  UINT8              BiosInt,
-  IN  IA32_REGISTER_SET  *Regs
-  )
-{
-  UINTN              Status;
-  IA32_REGISTER_SET  ThunkRegSet;
-  BOOLEAN            Ret;
-  UINT16             *Stack16;
-  BOOLEAN            Enabled;
-
-  ZeroMem (&ThunkRegSet, sizeof (ThunkRegSet));
-  ThunkRegSet.E.EFLAGS.Bits.Reserved_0 = 1;
-  ThunkRegSet.E.EFLAGS.Bits.Reserved_1 = 0;
-  ThunkRegSet.E.EFLAGS.Bits.Reserved_2 = 0;
-  ThunkRegSet.E.EFLAGS.Bits.Reserved_3 = 0;
-  ThunkRegSet.E.EFLAGS.Bits.IOPL       = 3;
-  ThunkRegSet.E.EFLAGS.Bits.NT         = 0;
-  ThunkRegSet.E.EFLAGS.Bits.IF         = 1;
-  ThunkRegSet.E.EFLAGS.Bits.TF         = 0;
-  ThunkRegSet.E.EFLAGS.Bits.CF         = 0;
-
-  ThunkRegSet.E.EDI = Regs->E.EDI;
-  ThunkRegSet.E.ESI = Regs->E.ESI;
-  ThunkRegSet.E.EBP = Regs->E.EBP;
-  ThunkRegSet.E.EBX = Regs->E.EBX;
-  ThunkRegSet.E.EDX = Regs->E.EDX;
-  ThunkRegSet.E.ECX = Regs->E.ECX;
-  ThunkRegSet.E.EAX = Regs->E.EAX;
-  ThunkRegSet.E.DS  = Regs->E.DS;
-  ThunkRegSet.E.ES  = Regs->E.ES;
-
-  //
-  // The call to Legacy16 is a critical section to EFI
-  //
-  Enabled = SaveAndDisableInterrupts ();
-
-  //
-  // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
-  //
-  Status = BiosDev->Legacy8259->SetMode (BiosDev->Legacy8259, Efi8259LegacyMode, NULL, NULL);
-  ASSERT_EFI_ERROR (Status);
-
-  Stack16 = (UINT16 *)((UINT8 *)BiosDev->ThunkContext->RealModeBuffer + BiosDev->ThunkContext->RealModeBufferSize - sizeof (UINT16));
-
-  ThunkRegSet.E.SS  = (UINT16)(((UINTN)Stack16 >> 16) << 12);
-  ThunkRegSet.E.ESP = (UINT16)(UINTN)Stack16;
-
-  ThunkRegSet.E.Eip                    = (UINT16)((volatile UINT32 *)NULL)[BiosInt];
-  ThunkRegSet.E.CS                     = (UINT16)(((volatile UINT32 *)NULL)[BiosInt] >> 16);
-  BiosDev->ThunkContext->RealModeState = &ThunkRegSet;
-  AsmThunk16 (BiosDev->ThunkContext);
-
-  //
-  // Restore protected mode interrupt state
-  //
-  Status = BiosDev->Legacy8259->SetMode (BiosDev->Legacy8259, Efi8259ProtectedMode, NULL, NULL);
-  ASSERT_EFI_ERROR (Status);
-
-  //
-  // End critical section
-  //
-  SetInterruptState (Enabled);
-
-  Regs->E.EDI = ThunkRegSet.E.EDI;
-  Regs->E.ESI = ThunkRegSet.E.ESI;
-  Regs->E.EBP = ThunkRegSet.E.EBP;
-  Regs->E.EBX = ThunkRegSet.E.EBX;
-  Regs->E.EDX = ThunkRegSet.E.EDX;
-  Regs->E.ECX = ThunkRegSet.E.ECX;
-  Regs->E.EAX = ThunkRegSet.E.EAX;
-  Regs->E.SS  = ThunkRegSet.E.SS;
-  Regs->E.CS  = ThunkRegSet.E.CS;
-  Regs->E.DS  = ThunkRegSet.E.DS;
-  Regs->E.ES  = ThunkRegSet.E.ES;
-
-  CopyMem (&(Regs->E.EFLAGS), &(ThunkRegSet.E.EFLAGS), sizeof (UINT32));
-
-  Ret = (BOOLEAN)(Regs->E.EFLAGS.Bits.CF == 1);
-
-  return Ret;
-}
diff --git a/Legacy/BootPlatform/CpuDxe/CpuDxe.c b/Legacy/BootPlatform/CpuDxe/CpuDxe.c
index 6b20f14330c..f9acf9db1a0 100644
--- a/Legacy/BootPlatform/CpuDxe/CpuDxe.c
+++ b/Legacy/BootPlatform/CpuDxe/CpuDxe.c
@@ -948,8 +948,8 @@ Return
 
 --*/
 {
-  EFI_IA32_REGISTER_SET  Regs;
-  UINT16                 OriginalVideoMode = (UINT16)-1;
+  IA32_REGISTER_SET  Regs;
+  UINT16             OriginalVideoMode = (UINT16)-1;
 
   //
   // Set new video mode
@@ -970,7 +970,7 @@ Return
     gBS->SetMem (&Regs, sizeof (Regs), 0);
     Regs.H.AH = 0x00;
     Regs.H.AL = (UINT8)NewVideoMode;
-    LegacyBiosInt86 (0x10, &Regs);
+    OcLegacyThunkBiosInt86 (&mThunkContext, gLegacy8259, 0x10, &Regs);
 
     //
     // VIDEO - TEXT-MODE CHARGEN - LOAD ROM 8x16 CHARACTER SET (VGA)
@@ -982,7 +982,7 @@ Return
     Regs.H.AH = 0x11;
     Regs.H.AL = 0x14;
     Regs.H.BL = 0;
-    LegacyBiosInt86 (0x10, &Regs);
+    OcLegacyThunkBiosInt86 (&mThunkContext, gLegacy8259, 0x10, &Regs);
   } else {
     //
     //    VESA SuperVGA BIOS - SET SuperVGA VIDEO MODE
@@ -998,7 +998,7 @@ Return
     gBS->SetMem (&Regs, sizeof (Regs), 0);
     Regs.X.AX = 0x4F02;
     Regs.X.BX = NewVideoMode;
-    LegacyBiosInt86 (0x10, &Regs);
+    OcLegacyThunkBiosInt86 (&mThunkContext, gLegacy8259, 0x10, &Regs);
     if (Regs.X.AX != 0x004F) {
       //
       // SORRY: Cannot set to video mode!
@@ -1138,7 +1138,7 @@ Routine Description:
     InstallInterruptHandler (InterruptVector, SystemTimerHandler);
   }
 
-  InitializeBiosIntCaller ();
+  OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
 
   //
   // Install CPU Architectural Protocol and the thunk protocol
@@ -1153,129 +1153,3 @@ Routine Description:
   ASSERT_EFI_ERROR (Status);
   return Status;
 }
-
-VOID
-InitializeBiosIntCaller (
-  VOID
-  )
-{
-  EFI_STATUS            Status;
-  UINT32                RealModeBufferSize;
-  UINT32                ExtraStackSize;
-  EFI_PHYSICAL_ADDRESS  LegacyRegionBase;
-  UINT32                LegacyRegionSize;
-
-  //
-  // Get LegacyRegion
-  //
-  AsmGetThunk16Properties (&RealModeBufferSize, &ExtraStackSize);
-  LegacyRegionSize = (((RealModeBufferSize + ExtraStackSize) / EFI_PAGE_SIZE) + 1) * EFI_PAGE_SIZE;
-  LegacyRegionBase = 0x0C0000;
-  Status           = gBS->AllocatePages (
-                            AllocateMaxAddress,
-                            EfiACPIMemoryNVS,
-                            EFI_SIZE_TO_PAGES (LegacyRegionSize),
-                            &LegacyRegionBase
-                            );
-  ASSERT_EFI_ERROR (Status);
-
-  ZeroMem ((VOID *)(UINTN)LegacyRegionBase, LegacyRegionSize);
-
-  mThunkContext.RealModeBuffer     = (VOID *)(UINTN)LegacyRegionBase;
-  mThunkContext.RealModeBufferSize = LegacyRegionSize;
-  mThunkContext.ThunkAttributes    = 3;
-  AsmPrepareThunk16 (&mThunkContext);
-}
-
-BOOLEAN
-EFIAPI
-LegacyBiosInt86 (
-  IN  UINT8                  BiosInt,
-  IN  EFI_IA32_REGISTER_SET  *Regs
-  )
-{
-  UINTN              Status;
-  BOOLEAN            InterruptsEnabled;
-  IA32_REGISTER_SET  ThunkRegSet;
-  BOOLEAN            Ret;
-  UINT16             *Stack16;
-
-  if (!gLegacy8259 || !mThunkContext.RealModeBuffer) {
-    return FALSE;
-  }
-
-  Regs->X.Flags.Reserved1 = 1;
-  Regs->X.Flags.Reserved2 = 0;
-  Regs->X.Flags.Reserved3 = 0;
-  Regs->X.Flags.Reserved4 = 0;
-  Regs->X.Flags.IOPL      = 3;
-  Regs->X.Flags.NT        = 0;
-  Regs->X.Flags.IF        = 1;
-  Regs->X.Flags.TF        = 0;
-  Regs->X.Flags.CF        = 0;
-
-  ZeroMem (&ThunkRegSet, sizeof (ThunkRegSet));
-  ThunkRegSet.E.EDI = Regs->E.EDI;
-  ThunkRegSet.E.ESI = Regs->E.ESI;
-  ThunkRegSet.E.EBP = Regs->E.EBP;
-  ThunkRegSet.E.EBX = Regs->E.EBX;
-  ThunkRegSet.E.EDX = Regs->E.EDX;
-  ThunkRegSet.E.ECX = Regs->E.ECX;
-  ThunkRegSet.E.EAX = Regs->E.EAX;
-  ThunkRegSet.E.DS  = Regs->E.DS;
-  ThunkRegSet.E.ES  = Regs->E.ES;
-
-  CopyMem (&(ThunkRegSet.E.EFLAGS), &(Regs->E.EFlags), sizeof (UINT32));
-
-  //
-  // The call to Legacy16 is a critical section to EFI
-  //
-  InterruptsEnabled = SaveAndDisableInterrupts ();
-
-  //
-  // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
-  //
-  Status = gLegacy8259->SetMode (gLegacy8259, Efi8259LegacyMode, NULL, NULL);
-  ASSERT_EFI_ERROR (Status);
-
-  Stack16  = (UINT16 *)((UINT8 *)mThunkContext.RealModeBuffer + mThunkContext.RealModeBufferSize - sizeof (UINT16));
-  Stack16 -= sizeof (ThunkRegSet.E.EFLAGS) / sizeof (UINT16);
-  CopyMem (Stack16, &ThunkRegSet.E.EFLAGS, sizeof (ThunkRegSet.E.EFLAGS));
-
-  ThunkRegSet.E.SS  = (UINT16)(((UINTN)Stack16 >> 16) << 12);
-  ThunkRegSet.E.ESP = (UINT16)(UINTN)Stack16;
-  ThunkRegSet.E.Eip = (UINT16)((volatile UINT32 *)NULL)[BiosInt];
-  ThunkRegSet.E.CS  = (UINT16)(((volatile UINT32 *)NULL)[BiosInt] >> 16);
-
-  mThunkContext.RealModeState = &ThunkRegSet;
-  AsmThunk16 (&mThunkContext);
-
-  //
-  // Restore protected mode interrupt state
-  //
-  Status = gLegacy8259->SetMode (gLegacy8259, Efi8259ProtectedMode, NULL, NULL);
-  ASSERT_EFI_ERROR (Status);
-
-  //
-  // End critical section
-  //
-  SetInterruptState (InterruptsEnabled);
-
-  Regs->E.EDI = ThunkRegSet.E.EDI;
-  Regs->E.ESI = ThunkRegSet.E.ESI;
-  Regs->E.EBP = ThunkRegSet.E.EBP;
-  Regs->E.EBX = ThunkRegSet.E.EBX;
-  Regs->E.EDX = ThunkRegSet.E.EDX;
-  Regs->E.ECX = ThunkRegSet.E.ECX;
-  Regs->E.EAX = ThunkRegSet.E.EAX;
-  Regs->E.SS  = ThunkRegSet.E.SS;
-  Regs->E.CS  = ThunkRegSet.E.CS;
-  Regs->E.DS  = ThunkRegSet.E.DS;
-  Regs->E.ES  = ThunkRegSet.E.ES;
-
-  CopyMem (&(Regs->E.EFlags), &(ThunkRegSet.E.EFLAGS), sizeof (UINT32));
-
-  Ret = (BOOLEAN)(Regs->E.EFlags.CF == 1);
-
-  return Ret;
-}
diff --git a/Legacy/BootPlatform/CpuDxe/CpuDxe.h b/Legacy/BootPlatform/CpuDxe/CpuDxe.h
index a28bd5cf330..10010d3ff60 100644
--- a/Legacy/BootPlatform/CpuDxe/CpuDxe.h
+++ b/Legacy/BootPlatform/CpuDxe/CpuDxe.h
@@ -26,6 +26,7 @@ Module Name:
 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
+#include <Library/OcLegacyThunkLib.h>
 #include <Library/PrintLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 
@@ -130,11 +131,4 @@ InitDescriptor (
   VOID
   );
 
-BOOLEAN
-EFIAPI
-LegacyBiosInt86 (
-  IN  UINT8                  BiosInt,
-  IN  EFI_IA32_REGISTER_SET  *Regs
-  );
-
 #endif
diff --git a/Legacy/BootPlatform/CpuDxe/CpuDxe.inf b/Legacy/BootPlatform/CpuDxe/CpuDxe.inf
index d105af515c1..214e665532b 100644
--- a/Legacy/BootPlatform/CpuDxe/CpuDxe.inf
+++ b/Legacy/BootPlatform/CpuDxe/CpuDxe.inf
@@ -26,6 +26,7 @@
   ENTRY_POINT                    = InitializeCpu
 
 [Packages]
+  OpenCorePkg/OpenCorePkg.dec
   OpenCorePkg/OpenDuetPkg.dec
   MdePkg/MdePkg.dec
   OvmfPkg/OvmfPkg.dec
@@ -35,6 +36,7 @@
   PrintLib
   UefiBootServicesTableLib
   BaseMemoryLib
+  OcLegacyThunkLib
 
 [Sources.Ia32]
   Ia32/CpuInterrupt.nasm
diff --git a/Legacy/BootPlatform/BiosVideo/LegacyBiosThunk.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
similarity index 83%
rename from Legacy/BootPlatform/BiosVideo/LegacyBiosThunk.c
rename to Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index 67ae8836260..421da8a3f79 100644
--- a/Legacy/BootPlatform/BiosVideo/LegacyBiosThunk.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -1,18 +1,20 @@
 /** @file
-  Provide legacy thunk interface for accessing Bios Video Rom.
-
-Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>
-This program and the accompanying materials
-are licensed and made available under the terms and conditions of the BSD License
-which accompanies this distribution.  The full text of the license may be found at
-http://opensource.org/licenses/bsd-license.php
-
-THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
-WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+  This file implements thunking to legacy 16-bit environment.
 
+  Copyright (c) 2023, Goldfish64. All rights reserved.<BR>
+  Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause
 **/
 
-#include "BiosVideo.h"
+#include <Uefi.h>
+
+#include <Library/UefiLib.h>
+#include <Library/DebugLib.h>
+#include <Library/BaseLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/OcLegacyThunkLib.h>
 
 /**
   Initialize legacy environment for BIOS INI caller.
@@ -20,7 +22,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
   @param ThunkContext   the instance pointer of THUNK_CONTEXT
 **/
 VOID
-InitializeBiosIntCaller (
+OcLegacyThunkInitializeBiosIntCaller (
   THUNK_CONTEXT  *ThunkContext
   )
 {
@@ -63,7 +65,7 @@ InitializeBiosIntCaller (
 
 **/
 VOID
-InitializeInterruptRedirection (
+OcLegacyThunkInitializeInterruptRedirection (
   IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259
   )
 {
@@ -133,10 +135,11 @@ InitializeInterruptRedirection (
 **/
 BOOLEAN
 EFIAPI
-LegacyBiosInt86 (
-  IN  BIOS_VIDEO_DEV     *BiosDev,
-  IN  UINT8              BiosInt,
-  IN  IA32_REGISTER_SET  *Regs
+OcLegacyThunkBiosInt86 (
+  IN  THUNK_CONTEXT             *ThunkContext,
+  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN  UINT8                     BiosInt,
+  IN  IA32_REGISTER_SET         *Regs
   )
 {
   UINTN              Status;
@@ -174,23 +177,23 @@ LegacyBiosInt86 (
   //
   // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
   //
-  Status = BiosDev->Legacy8259->SetMode (BiosDev->Legacy8259, Efi8259LegacyMode, NULL, NULL);
+  Status = Legacy8259->SetMode (Legacy8259, Efi8259LegacyMode, NULL, NULL);
   ASSERT_EFI_ERROR (Status);
 
-  Stack16 = (UINT16 *)((UINT8 *)BiosDev->ThunkContext->RealModeBuffer + BiosDev->ThunkContext->RealModeBufferSize - sizeof (UINT16));
+  Stack16 = (UINT16 *)((UINT8 *)ThunkContext->RealModeBuffer + ThunkContext->RealModeBufferSize - sizeof (UINT16));
 
   ThunkRegSet.E.SS  = (UINT16)(((UINTN)Stack16 >> 16) << 12);
   ThunkRegSet.E.ESP = (UINT16)(UINTN)Stack16;
 
   ThunkRegSet.E.Eip                    = (UINT16)((volatile UINT32 *)NULL)[BiosInt];
   ThunkRegSet.E.CS                     = (UINT16)(((volatile UINT32 *)NULL)[BiosInt] >> 16);
-  BiosDev->ThunkContext->RealModeState = &ThunkRegSet;
-  AsmThunk16 (BiosDev->ThunkContext);
+  ThunkContext->RealModeState = &ThunkRegSet;
+  AsmThunk16 (ThunkContext);
 
   //
   // Restore protected mode interrupt state
   //
-  Status = BiosDev->Legacy8259->SetMode (BiosDev->Legacy8259, Efi8259ProtectedMode, NULL, NULL);
+  Status = Legacy8259->SetMode (Legacy8259, Efi8259ProtectedMode, NULL, NULL);
   ASSERT_EFI_ERROR (Status);
 
   //
diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
new file mode 100644
index 00000000000..7627d27a196
--- /dev/null
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
@@ -0,0 +1,49 @@
+## @file
+#
+#  Component description file for the library handling thunking to legacy 16-bit environment.
+#
+#  Copyright (C) 2023, Goldfish64. All rights reserved.<BR>
+#
+# All rights reserved.
+#
+# This program and the accompanying materials
+# are licensed and made available under the terms and conditions of the BSD License
+# which accompanies this distribution.  The full text of the license may be found at
+# http://opensource.org/licenses/bsd-license.php
+#
+# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = OcLegacyThunkLib
+  FILE_GUID                      = 133D1AF1-8BB5-4F12-AC93-2DF858D9935F
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = OcLegacyThunkLib|PEIM DXE_DRIVER DXE_RUNTIME_DRIVER UEFI_DRIVER UEFI_APPLICATION DXE_SMM_DRIVER
+
+#
+# The following information is for reference only and not required by the build tools.
+#
+#  VALID_ARCHITECTURES           = IA32 X64 IPF EBC
+#
+
+[Sources]
+  OcLegacyThunkLib.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OpenCorePkg/OpenCorePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[Protocols]
+  gEfiLegacy8259ProtocolGuid
+
+[LibraryClasses]
+  BaseMemoryLib
+  DebugLib
+  MemoryAllocationLib
+  UefiBootServicesTableLib
+  UefiLib
diff --git a/OpenCorePkg.dec b/OpenCorePkg.dec
index 49ac93973c5..ee0e77bdabe 100755
--- a/OpenCorePkg.dec
+++ b/OpenCorePkg.dec
@@ -900,6 +900,9 @@
   ##  @libraryclass
   OcInputLib|Include/Acidanthera/Library/OcInputLib.h
 
+  ##  @libraryclass
+  OcLegacyThunkLib|Include/Acidanthera/Library/OcLegacyThunkLib.h
+
   ##  @libraryclass
   OcLogAggregatorLib|Include/Acidanthera/Library/OcLogAggregatorLib.h
 
diff --git a/OpenCorePkg.dsc b/OpenCorePkg.dsc
index 212bab3be88..01552ceeeae 100755
--- a/OpenCorePkg.dsc
+++ b/OpenCorePkg.dsc
@@ -114,6 +114,7 @@
   OcHeciLib|OpenCorePkg/Library/OcHeciLib/OcHeciLib.inf
   OcHiiDatabaseLocalLib|OpenCorePkg/Library/OcHiiDatabaseLib/OcHiiDatabaseLocalLib.inf
   OcInputLib|OpenCorePkg/Library/OcInputLib/OcInputLib.inf
+  OcLegacyThunkLib|OpenCorePkg/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
   OcLogAggregatorLib|OpenCorePkg/Library/OcLogAggregatorLib/OcLogAggregatorLib.inf
   OcMachoLib|OpenCorePkg/Library/OcMachoLib/OcMachoLib.inf
   OcMacInfoLib|OpenCorePkg/Library/OcMacInfoLib/OcMacInfoLib.inf
diff --git a/OpenDuetPkg.dsc b/OpenDuetPkg.dsc
index 97a30d07475..b7af0e37624 100644
--- a/OpenDuetPkg.dsc
+++ b/OpenDuetPkg.dsc
@@ -106,6 +106,7 @@
   OcDevicePathLib|OpenCorePkg/Library/OcDevicePathLib/OcDevicePathLib.inf
   OcFileLib|OpenCorePkg/Library/OcFileLib/OcFileLib.inf
   OcGuardLib|OpenCorePkg/Library/OcGuardLib/OcGuardLib.inf
+  OcLegacyThunkLib|OpenCorePkg/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
   OcMemoryLib|OpenCorePkg/Library/OcMemoryLib/OcMemoryLib.inf
   OcMiscLib|OpenCorePkg/Library/OcMiscLib/OcMiscLib.inf
   OcStringLib|OpenCorePkg/Library/OcStringLib/OcStringLib.inf

From 83af80a2cf535497fe752912e4821ac8cab8cd29 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 7 Aug 2023 19:52:14 -0500
Subject: [PATCH 19/55] OcLegacyThunkLib: Fix codestyle

---
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index 421da8a3f79..aec83a87c7a 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -185,8 +185,8 @@ OcLegacyThunkBiosInt86 (
   ThunkRegSet.E.SS  = (UINT16)(((UINTN)Stack16 >> 16) << 12);
   ThunkRegSet.E.ESP = (UINT16)(UINTN)Stack16;
 
-  ThunkRegSet.E.Eip                    = (UINT16)((volatile UINT32 *)NULL)[BiosInt];
-  ThunkRegSet.E.CS                     = (UINT16)(((volatile UINT32 *)NULL)[BiosInt] >> 16);
+  ThunkRegSet.E.Eip           = (UINT16)((volatile UINT32 *)NULL)[BiosInt];
+  ThunkRegSet.E.CS            = (UINT16)(((volatile UINT32 *)NULL)[BiosInt] >> 16);
   ThunkContext->RealModeState = &ThunkRegSet;
   AsmThunk16 (ThunkContext);
 

From af725143d75209b802da589f733c8b6c1ddaadf1 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 7 Aug 2023 20:06:10 -0500
Subject: [PATCH 20/55] OcLegacyThunkLib: Fix comments

---
 Include/Acidanthera/Library/OcLegacyThunkLib.h | 11 ++++++-----
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c    | 11 ++++++-----
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/Include/Acidanthera/Library/OcLegacyThunkLib.h b/Include/Acidanthera/Library/OcLegacyThunkLib.h
index 4c2a97c3056..991fa07a210 100644
--- a/Include/Acidanthera/Library/OcLegacyThunkLib.h
+++ b/Include/Acidanthera/Library/OcLegacyThunkLib.h
@@ -23,7 +23,7 @@
 /**
   Initialize legacy environment for BIOS INI caller.
 
-  @param ThunkContext   the instance pointer of THUNK_CONTEXT
+  @param ThunkContext   The instance pointer of THUNK_CONTEXT.
 **/
 VOID
 OcLegacyThunkInitializeBiosIntCaller (
@@ -50,13 +50,14 @@ OcLegacyThunkInitializeInterruptRedirection (
   of BiosInt. Regs will contain the 16-bit register context on entry and
   exit.
 
-  @param  This    Protocol instance pointer.
-  @param  BiosInt Processor interrupt vector to invoke
-  @param  Reg     Register contexted passed into (and returned) from thunk to 16-bit mode
+  @param  ThunkContext    The instance pointer of THUNK_CONTEXT.
+  @param  Legacy8259      Instance pointer for EFI_LEGACY_8259_PROTOCOL.
+  @param  BiosInt         Processor interrupt vector to invoke
+  @param  Reg             Register contexted passed into (and returned) from thunk to 16-bit mode
 
   @retval TRUE   Thunk completed, and there were no BIOS errors in the target code.
                  See Regs for status.
-  @retval FALSE  There was a BIOS erro in the target code.
+  @retval FALSE  There was a BIOS error in the target code.
 **/
 BOOLEAN
 EFIAPI
diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index aec83a87c7a..24e10724f11 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -19,7 +19,7 @@
 /**
   Initialize legacy environment for BIOS INI caller.
 
-  @param ThunkContext   the instance pointer of THUNK_CONTEXT
+  @param ThunkContext   The instance pointer of THUNK_CONTEXT.
 **/
 VOID
 OcLegacyThunkInitializeBiosIntCaller (
@@ -125,13 +125,14 @@ OcLegacyThunkInitializeInterruptRedirection (
   of BiosInt. Regs will contain the 16-bit register context on entry and
   exit.
 
-  @param  This    Protocol instance pointer.
-  @param  BiosInt Processor interrupt vector to invoke
-  @param  Reg     Register contexted passed into (and returned) from thunk to 16-bit mode
+  @param  ThunkContext    The instance pointer of THUNK_CONTEXT.
+  @param  Legacy8259      Instance pointer for EFI_LEGACY_8259_PROTOCOL.
+  @param  BiosInt         Processor interrupt vector to invoke
+  @param  Reg             Register contexted passed into (and returned) from thunk to 16-bit mode
 
   @retval TRUE   Thunk completed, and there were no BIOS errors in the target code.
                  See Regs for status.
-  @retval FALSE  There was a BIOS erro in the target code.
+  @retval FALSE  There was a BIOS error in the target code.
 **/
 BOOLEAN
 EFIAPI

From 4776b9873d45090f6c330f791dcf6235a7690699 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Tue, 8 Aug 2023 17:11:01 -0500
Subject: [PATCH 21/55] OcLegacyThunkLib: Return status from init functions

---
 Include/Acidanthera/Library/OcLegacyThunkLib.h |  4 ++--
 Legacy/BootPlatform/BiosVideo/BiosVideo.c      | 11 +++++++++--
 Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c     | 11 +++++++++--
 Legacy/BootPlatform/CpuDxe/CpuDxe.c            |  3 ++-
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c    | 16 ++++++++++++----
 5 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/Include/Acidanthera/Library/OcLegacyThunkLib.h b/Include/Acidanthera/Library/OcLegacyThunkLib.h
index 991fa07a210..cb651446aa5 100644
--- a/Include/Acidanthera/Library/OcLegacyThunkLib.h
+++ b/Include/Acidanthera/Library/OcLegacyThunkLib.h
@@ -25,7 +25,7 @@
 
   @param ThunkContext   The instance pointer of THUNK_CONTEXT.
 **/
-VOID
+EFI_STATUS
 OcLegacyThunkInitializeBiosIntCaller (
   IN OUT THUNK_CONTEXT  *ThunkContext
   );
@@ -40,7 +40,7 @@ OcLegacyThunkInitializeBiosIntCaller (
    @param Legacy8259  Instance pointer for EFI_LEGACY_8259_PROTOCOL.
 
 **/
-VOID
+EFI_STATUS
 OcLegacyThunkInitializeInterruptRedirection (
   IN EFI_LEGACY_8259_PROTOCOL  *Legacy8259
   );
diff --git a/Legacy/BootPlatform/BiosVideo/BiosVideo.c b/Legacy/BootPlatform/BiosVideo/BiosVideo.c
index 010c5f625b1..1188832ddf8 100644
--- a/Legacy/BootPlatform/BiosVideo/BiosVideo.c
+++ b/Legacy/BootPlatform/BiosVideo/BiosVideo.c
@@ -209,8 +209,15 @@ BiosVideoDriverBindingStart (
       goto Done;
     }
 
-    OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
-    OcLegacyThunkInitializeInterruptRedirection (mLegacy8259);
+    Status = OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
+    if (EFI_ERROR (Status)) {
+      goto Done;
+    }
+
+    Status = OcLegacyThunkInitializeInterruptRedirection (mLegacy8259);
+    if (EFI_ERROR (Status)) {
+      goto Done;
+    }
   }
 
   //
diff --git a/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c b/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c
index a6598f951ae..10ca63a2fab 100644
--- a/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c
+++ b/Legacy/BootPlatform/BlockIoDxe/BiosBlkIo.c
@@ -255,8 +255,15 @@ BiosBlockIoDriverBindingStart (
     goto Error;
   }
 
-  OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
-  OcLegacyThunkInitializeInterruptRedirection (Legacy8259);
+  Status = OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
+  if (EFI_ERROR (Status)) {
+    goto Error;
+  }
+
+  Status = OcLegacyThunkInitializeInterruptRedirection (Legacy8259);
+  if (EFI_ERROR (Status)) {
+    goto Error;
+  }
 
   //
   // Open the IO Abstraction(s) needed
diff --git a/Legacy/BootPlatform/CpuDxe/CpuDxe.c b/Legacy/BootPlatform/CpuDxe/CpuDxe.c
index f9acf9db1a0..8d900be4e39 100644
--- a/Legacy/BootPlatform/CpuDxe/CpuDxe.c
+++ b/Legacy/BootPlatform/CpuDxe/CpuDxe.c
@@ -1138,7 +1138,8 @@ Routine Description:
     InstallInterruptHandler (InterruptVector, SystemTimerHandler);
   }
 
-  OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
+  Status = OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
+  ASSERT_EFI_ERROR (Status);
 
   //
   // Install CPU Architectural Protocol and the thunk protocol
diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index 24e10724f11..f33c788470d 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -21,7 +21,7 @@
 
   @param ThunkContext   The instance pointer of THUNK_CONTEXT.
 **/
-VOID
+EFI_STATUS
 OcLegacyThunkInitializeBiosIntCaller (
   THUNK_CONTEXT  *ThunkContext
   )
@@ -44,7 +44,9 @@ OcLegacyThunkInitializeBiosIntCaller (
                             EFI_SIZE_TO_PAGES (LegacyRegionSize),
                             &LegacyRegionBase
                             );
-  ASSERT_EFI_ERROR (Status);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
 
   ZeroMem ((VOID *)(UINTN)LegacyRegionBase, LegacyRegionSize);
 
@@ -52,6 +54,7 @@ OcLegacyThunkInitializeBiosIntCaller (
   ThunkContext->RealModeBufferSize = LegacyRegionSize;
   ThunkContext->ThunkAttributes    = THUNK_ATTRIBUTE_BIG_REAL_MODE|THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15;
   AsmPrepareThunk16 (ThunkContext);
+  return Status;
 }
 
 /**
@@ -64,7 +67,7 @@ OcLegacyThunkInitializeBiosIntCaller (
    @param Legacy8259  Instance pointer for EFI_LEGACY_8259_PROTOCOL.
 
 **/
-VOID
+EFI_STATUS
 OcLegacyThunkInitializeInterruptRedirection (
   IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259
   )
@@ -98,7 +101,9 @@ OcLegacyThunkInitializeInterruptRedirection (
                               EFI_SIZE_TO_PAGES (LegacyRegionLength),
                               &LegacyRegionBase
                               );
-  ASSERT_EFI_ERROR (Status);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
 
   //
   // Copy code to legacy region
@@ -118,6 +123,9 @@ OcLegacyThunkInitializeInterruptRedirection (
   for (Index = 0; Index < 8; Index++) {
     IdtArray[ProtectedModeBaseVector + Index] = ((EFI_SEGMENT (LegacyRegionBase + Index * 4)) << 16) | (EFI_OFFSET (LegacyRegionBase + Index * 4));
   }
+
+  return Status;
+}
 }
 
 /**

From 7f83d12384b905ac62503e47c0f8f7dae5c553cb Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Tue, 8 Aug 2023 19:31:19 -0500
Subject: [PATCH 22/55] OcLegacyThunkLib: Fix previous commit

---
 .../Acidanthera/Library/OcLegacyThunkLib.h    |  8 +++
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c   | 60 +++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/Include/Acidanthera/Library/OcLegacyThunkLib.h b/Include/Acidanthera/Library/OcLegacyThunkLib.h
index cb651446aa5..c5e091247f4 100644
--- a/Include/Acidanthera/Library/OcLegacyThunkLib.h
+++ b/Include/Acidanthera/Library/OcLegacyThunkLib.h
@@ -45,6 +45,14 @@ OcLegacyThunkInitializeInterruptRedirection (
   IN EFI_LEGACY_8259_PROTOCOL  *Legacy8259
   );
 
+/**
+   Disconnect all EFI graphics device handles in preparation for calling to legacy mode.
+**/
+VOID
+OcLegacyThunkDisconnectEfiGraphics (
+  VOID
+  );
+
 /**
   Thunk to 16-bit real mode and execute a software interrupt with a vector
   of BiosInt. Regs will contain the 16-bit register context on entry and
diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index f33c788470d..35c3099e7bd 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -126,6 +126,66 @@ OcLegacyThunkInitializeInterruptRedirection (
 
   return Status;
 }
+
+/**
+   Disconnect all EFI graphics device handles in preparation for calling to legacy mode.
+**/
+VOID
+OcLegacyThunkDisconnectEfiGraphics (
+  VOID
+  )
+{
+  EFI_STATUS           Status;
+  UINTN                HandleCount;
+  EFI_HANDLE           *HandleBuffer;
+  UINTN                Index;
+  EFI_PCI_IO_PROTOCOL  *PciIo;
+  PCI_CLASSCODE        ClassCode;
+
+  Status = gBS->LocateHandleBuffer (
+                  ByProtocol,
+                  &gEfiPciIoProtocolGuid,
+                  NULL,
+                  &HandleCount,
+                  &HandleBuffer
+                  );
+  if (EFI_ERROR (Status)) {
+    return;
+  }
+
+  for (Index = 0; Index < HandleCount; ++Index) {
+    Status = gBS->HandleProtocol (
+                    HandleBuffer[Index],
+                    &gEfiPciIoProtocolGuid,
+                    (VOID **)&PciIo
+                    );
+
+    if (EFI_ERROR (Status)) {
+      continue;
+    }
+
+    Status = PciIo->Pci.Read (
+                          PciIo,
+                          EfiPciIoWidthUint8,
+                          PCI_CLASSCODE_OFFSET,
+                          sizeof (PCI_CLASSCODE) / sizeof (UINT8),
+                          &ClassCode
+                          );
+    if (EFI_ERROR (Status)) {
+      continue;
+    }
+
+    if ((ClassCode.BaseCode == PCI_CLASS_DISPLAY) && (ClassCode.SubClassCode == PCI_CLASS_DISPLAY_VGA)) {
+      Status = gBS->DisconnectController (
+            HandleBuffer[Index],
+            NULL,
+            NULL
+            );
+      DEBUG ((DEBUG_INFO, "OCLT: Disconnected graphics controller - %r\n", Status));
+    }
+  }
+
+  FreePool (HandleBuffer);
 }
 
 /**

From b4bb4b55df36824e3516d0481736537e20ffcf52 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Tue, 8 Aug 2023 19:56:49 -0500
Subject: [PATCH 23/55] OcLegacyThunkLib: Fix previous commit

---
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index 35c3099e7bd..f37eecb9adf 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -8,13 +8,20 @@
 
 #include <Uefi.h>
 
-#include <Library/UefiLib.h>
-#include <Library/DebugLib.h>
+#include <IndustryStandard/Pci.h>
+
 #include <Library/BaseLib.h>
-#include <Library/UefiBootServicesTableLib.h>
 #include <Library/BaseMemoryLib.h>
+#include <Library/DebugLib.h>
+#include <Library/IoLib.h>
 #include <Library/MemoryAllocationLib.h>
+#include <Library/OcDeviceMiscLib.h>
 #include <Library/OcLegacyThunkLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+#include <Protocol/PciIo.h>
+#include <Protocol/Timer.h>
 
 /**
   Initialize legacy environment for BIOS INI caller.

From 7601bc5ad409c80a2aa0b7c0dcc87ee0ed6b1868 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Wed, 9 Aug 2023 19:25:24 -0500
Subject: [PATCH 24/55] OcLegacyThunkLib: Add missing package

---
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c   | 8 ++++----
 Library/OcLegacyThunkLib/OcLegacyThunkLib.inf | 1 +
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index f37eecb9adf..bc3422ae844 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -184,10 +184,10 @@ OcLegacyThunkDisconnectEfiGraphics (
 
     if ((ClassCode.BaseCode == PCI_CLASS_DISPLAY) && (ClassCode.SubClassCode == PCI_CLASS_DISPLAY_VGA)) {
       Status = gBS->DisconnectController (
-            HandleBuffer[Index],
-            NULL,
-            NULL
-            );
+                      HandleBuffer[Index],
+                      NULL,
+                      NULL
+                      );
       DEBUG ((DEBUG_INFO, "OCLT: Disconnected graphics controller - %r\n", Status));
     }
   }
diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
index 7627d27a196..432491c9219 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
@@ -37,6 +37,7 @@
   MdePkg/MdePkg.dec
   OpenCorePkg/OpenCorePkg.dec
   OvmfPkg/OvmfPkg.dec
+  UefiCpuPkg/UefiCpuPkg.dec
 
 [Protocols]
   gEfiLegacy8259ProtocolGuid

From 9a29c0126428254570dce398205504e9284f06d2 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Wed, 9 Aug 2023 19:35:32 -0500
Subject: [PATCH 25/55] OpenLegacyBoot: Move legacy functionality into
 standalone driver

---
 .../Acidanthera/Library/OcBootManagementLib.h |  43 +--
 .../Acidanthera/Library/OcLegacyThunkLib.h    |  12 +
 Library/OcBootManagementLib/BootEntryInfo.c   |  28 --
 .../OcBootManagementLib/BootEntryManagement.c | 334 ++++--------------
 .../BootManagementInternal.h                  |  34 --
 .../OcBootManagementLib/DefaultEntryChoice.c  |  29 +-
 .../OcBootManagementLib/OcBootManagementLib.c |   5 -
 .../OcBootManagementLib.inf                   |   3 -
 .../OcBootManagementLib/PolicyManagement.c    |   3 +-
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c   | 174 +++++++++
 OpenCorePkg.dsc                               |   1 +
 Platform/OpenLegacyBoot/LegacyBootInternal.h  |  44 +++
 .../OpenLegacyBoot}/LegacyBootSupport.c       | 139 ++++++--
 Platform/OpenLegacyBoot/OpenLegacyBoot.c      | 277 +++++++++++++++
 Platform/OpenLegacyBoot/OpenLegacyBoot.inf    |  44 +++
 Platform/ResetNvramEntry/ResetNvramEntry.c    |   3 +-
 Platform/ToggleSipEntry/ToggleSipEntry.c      |   3 +-
 build_oc.tool                                 |   1 +
 18 files changed, 754 insertions(+), 423 deletions(-)
 create mode 100644 Platform/OpenLegacyBoot/LegacyBootInternal.h
 rename {Library/OcBootManagementLib => Platform/OpenLegacyBoot}/LegacyBootSupport.c (78%)
 create mode 100644 Platform/OpenLegacyBoot/OpenLegacyBoot.c
 create mode 100644 Platform/OpenLegacyBoot/OpenLegacyBoot.inf

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index 10fcc44e92e..7ce19037501 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -153,25 +153,6 @@ typedef UINT32 OC_BOOT_ENTRY_TYPE;
 #define OC_BOOT_EXTERNAL_TOOL       BIT7
 #define OC_BOOT_SYSTEM              BIT8
 
-/**
-  Legacy system boot type.
-**/
-typedef enum OC_LEGACY_BOOT_TYPE_ {
-  OcLegacyBootTypeNone,
-  OcLegacyBootTypeApple,
-  OcLegacyBootTypeLegacyBios
-} OC_LEGACY_BOOT_TYPE;
-
-/**
-  Legacy operating system type.
-**/
-typedef enum OC_LEGACY_OS_TYPE_ {
-  OcLegacyOsTypeNone,
-  OcLegacyOsTypeWindowsNtldr,
-  OcLegacyOsTypeWindowsBootmgr,
-  OcLegacyOsTypeIsoLinux
-} OC_LEGACY_OS_TYPE;
-
 /**
   Picker mode.
 **/
@@ -209,7 +190,8 @@ typedef enum OC_PICKER_MODE_ {
 typedef
 EFI_STATUS
 (*OC_BOOT_SYSTEM_ACTION) (
-  IN OUT          OC_PICKER_CONTEXT  *PickerContext
+  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
+  IN              VOID               *ActionContext
   );
 
 /**
@@ -231,6 +213,10 @@ typedef struct OC_BOOT_ENTRY_ {
   //
   OC_BOOT_SYSTEM_ACTION       SystemAction;
   //
+  // Context for action to perform on execution for system entries.
+  //
+  VOID                        *SystemActionContext;
+  //
   // Id under which to save entry as default.
   //
   CHAR16                      *Id;
@@ -281,11 +267,6 @@ typedef struct OC_BOOT_ENTRY_ {
   //
   BOOLEAN                     IsAppleInstaller;
   //
-  // Describes type of legacy OS to be booted.
-  // Set when entry is to be booted through legacy interface.
-  //
-  OC_LEGACY_OS_TYPE           LegacyOsType;
-  //
   // Should make this option default boot option.
   //
   BOOLEAN                     SetDefault;
@@ -372,10 +353,6 @@ struct OC_BOOT_FILESYSTEM_ {
   //
   BOOLEAN               LoaderFs;
   //
-  // Legacy bootsector type.
-  //
-  OC_LEGACY_OS_TYPE     LegacyOsType;
-  //
   // Contains recovery on the filesystem.
   //
   BOOLEAN               HasSelfRecovery;
@@ -628,6 +605,10 @@ typedef struct {
   //
   OC_BOOT_SYSTEM_ACTION    SystemAction;
   //
+  // System action context. Boot Entry Protocol only. Optional.
+  //
+  VOID                     *SystemActionContext;
+  //
   // Audio base path for system action. Boot Entry Protocol only. Optional.
   //
   CHAR8                    *AudioBasePath;
@@ -977,10 +958,6 @@ struct OC_PICKER_CONTEXT_ {
   //
   CONST CHAR8                 *InstanceIdentifier;
   //
-  // Legacy boot method type.
-  //
-  OC_LEGACY_BOOT_TYPE         LegacyBootType;
-  //
   // Enable polling boot arguments.
   //
   BOOLEAN                     PollAppleHotKeys;
diff --git a/Include/Acidanthera/Library/OcLegacyThunkLib.h b/Include/Acidanthera/Library/OcLegacyThunkLib.h
index c5e091247f4..0808cadb1bd 100644
--- a/Include/Acidanthera/Library/OcLegacyThunkLib.h
+++ b/Include/Acidanthera/Library/OcLegacyThunkLib.h
@@ -76,4 +76,16 @@ OcLegacyThunkBiosInt86 (
   IN  IA32_REGISTER_SET         *Regs
   );
 
+BOOLEAN
+EFIAPI
+OcLegacyThunkFarCall86 (
+  IN  THUNK_CONTEXT             *ThunkContext,
+  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN  UINT16                    Segment,
+  IN  UINT16                    Offset,
+  IN  IA32_REGISTER_SET         *Regs,
+  IN  VOID                      *Stack,
+  IN  UINTN                     StackSize
+  );
+
 #endif // OC_LEGACY_THUNK_LIB_H
diff --git a/Library/OcBootManagementLib/BootEntryInfo.c b/Library/OcBootManagementLib/BootEntryInfo.c
index 984944e7b8b..b150ea334bb 100644
--- a/Library/OcBootManagementLib/BootEntryInfo.c
+++ b/Library/OcBootManagementLib/BootEntryInfo.c
@@ -890,31 +890,3 @@ InternalDescribeBootEntry (
 
   return EFI_SUCCESS;
 }
-
-EFI_STATUS
-InternalDescribeLegacyBootEntry (
-  IN     OC_BOOT_CONTEXT    *BootContext,
-  IN     OC_LEGACY_OS_TYPE  LegacyOsType,
-  IN OUT OC_BOOT_ENTRY      *BootEntry
-  )
-{
-  ASSERT (LegacyOsType != OcLegacyOsTypeNone);
-
-  //
-  // Name is based on previously detected boot sector type.
-  //
-  switch (LegacyOsType) {
-    case OcLegacyOsTypeWindowsBootmgr:
-    case OcLegacyOsTypeWindowsNtldr:
-      BootEntry->Type = OC_BOOT_WINDOWS;
-      BootEntry->Name = AllocateCopyPool (sizeof (L"Windows (legacy)"), L"Windows (legacy)");
-      break;
-
-    default:
-      BootEntry->Type = OC_BOOT_UNKNOWN;
-      BootEntry->Name = AllocateCopyPool (sizeof (L"Unknown OS (legacy)"), L"Unknown OS (legacy)");
-      break;
-  }
-
-  return EFI_SUCCESS;
-}
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index af98f546de9..c27932c6292 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -720,10 +720,11 @@ InternalAddBootEntryFromCustomEntry (
     ));
 
   if (CustomEntry->SystemAction) {
-    BootEntry->Type          = OC_BOOT_SYSTEM;
-    BootEntry->SystemAction  = CustomEntry->SystemAction;
-    BootEntry->AudioBasePath = CustomEntry->AudioBasePath;
-    BootEntry->AudioBaseType = CustomEntry->AudioBaseType;
+    BootEntry->Type                = OC_BOOT_SYSTEM;
+    BootEntry->SystemAction        = CustomEntry->SystemAction;
+    BootEntry->SystemActionContext = CustomEntry->SystemActionContext;
+    BootEntry->AudioBasePath       = CustomEntry->AudioBasePath;
+    BootEntry->AudioBaseType       = CustomEntry->AudioBaseType;
   } else if (CustomEntry->Tool) {
     BootEntry->Type = OC_BOOT_EXTERNAL_TOOL;
     UnicodeUefiSlashes (PathName);
@@ -1173,100 +1174,6 @@ AddBootEntryFromSelfRecovery (
   return Status;
 }
 
-/**
-  Create bootable entries from legacy boot partitons.
-
-  @param[in,out] BootContext   Context of filesystems.
-  @param[in,out] FileSystem    Filesystem to scan for recovery.
-
-  @retval EFI_SUCCESS on success.
-**/
-STATIC
-EFI_STATUS
-AddBootEntryFromLegacyPartition (
-  IN OUT OC_BOOT_CONTEXT     *BootContext,
-  IN OUT OC_BOOT_FILESYSTEM  *FileSystem
-  )
-{
-  EFI_STATUS                Status;
-  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
-  OC_BOOT_ENTRY             *BootEntry;
-
-  //
-  // Only support legacy filesystems.
-  //
-  if (FileSystem->LegacyOsType == OcLegacyOsTypeNone) {
-    return EFI_UNSUPPORTED;
-  }
-
-  Status = gBS->HandleProtocol (
-                  FileSystem->Handle,
-                  &gEfiDevicePathProtocolGuid,
-                  (VOID **)&DevicePath
-                  );
-  if (EFI_ERROR (Status)) {
-    return EFI_UNSUPPORTED;
-  }
-
-  DebugPrintDevicePath (DEBUG_INFO, "OCB: Adding legacy entry for disk", DevicePath);
-
-  //
-  // Allocate, initialise, and describe boot entry.
-  //
-  BootEntry = AllocateZeroPool (sizeof (*BootEntry));
-  if (BootEntry == NULL) {
-    return EFI_OUT_OF_RESOURCES;
-  }
-
-  BootEntry->DevicePath = DuplicateDevicePath (DevicePath);
-  if (BootEntry->DevicePath == NULL) {
-    FreePool (BootEntry);
-    return EFI_OUT_OF_RESOURCES;
-  }
-
-  BootEntry->IsExternal   = FileSystem->External;
-  BootEntry->LegacyOsType = FileSystem->LegacyOsType;
-  BootEntry->LaunchInText = TRUE;
-
-  //
-  // Load options are set based on type of disk.
-  // Internal disk = "HD"
-  // External disk = "USB"
-  // Optical disk  = "CD"
-  //
-  if (BootEntry->IsExternal) {
-    if (OcIsDiskCdRom (BootEntry->DevicePath)) {
-      BootEntry->LoadOptionsSize = L_STR_SIZE ("CD");
-      BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("CD"), "CD");
-    } else {
-      BootEntry->LoadOptionsSize = L_STR_SIZE ("USB");
-      BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("USB"), "USB");
-    }
-  } else {
-    BootEntry->LoadOptionsSize = L_STR_SIZE ("HD");
-    BootEntry->LoadOptions     = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
-  }
-
-  if (BootEntry->LoadOptions == NULL) {
-    FreePool (BootEntry);
-    return EFI_OUT_OF_RESOURCES;
-  }
-
-  Status = InternalDescribeLegacyBootEntry (BootContext, FileSystem->LegacyOsType, BootEntry);
-  if (EFI_ERROR (Status)) {
-    FreePool (BootEntry);
-    return Status;
-  }
-
-  RegisterBootOption (
-    BootContext,
-    FileSystem,
-    BootEntry
-    );
-
-  return EFI_SUCCESS;
-}
-
 /**
   Create bootable entries from boot options.
 
@@ -1303,13 +1210,11 @@ AddBootEntryFromBootOption (
   EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
   EFI_DEVICE_PATH_PROTOCOL  *RemainingDevicePath;
   EFI_DEVICE_PATH_PROTOCOL  *ExpandedDevicePath;
-  EFI_DEVICE_PATH_PROTOCOL  *ActivePartitionDevicePath;
   EFI_HANDLE                FileSystemHandle;
   OC_BOOT_FILESYSTEM        *FileSystem;
   UINTN                     DevicePathSize;
   INTN                      NumPatchedNodes;
   BOOLEAN                   IsAppleLegacy;
-  BOOLEAN                   IsLegacyEntry;
   BOOLEAN                   IsRoot;
   EFI_LOAD_OPTION           *LoadOption;
   UINTN                     LoadOptionSize;
@@ -1358,7 +1263,6 @@ AddBootEntryFromBootOption (
   // BootCamp device path will point to disk instead of partition.
   //
   IsAppleLegacy = InternalIsAppleLegacyLoadApp (DevicePath);
-  IsLegacyEntry = FALSE;
   if (IsAppleLegacy) {
     FreePool (DevicePath);
     Status = GetVariable2 (
@@ -1400,15 +1304,7 @@ AddBootEntryFromBootOption (
   }
 
   //
-  // Handle Apple BootCamp device path.
-  //
-  // If we have a legacy installation of Windows in place, Device Path
-  // will point to disk containing the active partition to boot. This will
-  // need to be expanded to the full Device Path of the active partition.
-  //
-  // If not, locate the EFI partition Device Path to boot Windows in UEFI mode.
-  // Installing Windows on Macs that normally use legacy mode for Boot Camp
-  // will exhibit this behavior if Windows is selected as a startup disk from within macOS.
+  // Expand BootCamp device path to EFI partition device path.
   //
   if (IsAppleLegacy) {
     //
@@ -1421,36 +1317,12 @@ AddBootEntryFromBootOption (
       return EFI_NOT_FOUND;
     }
 
-    //
-    // Attempt to locate active MBR partition Device Path.
-    //
-    RemainingDevicePath       = DevicePath;
-    ActivePartitionDevicePath = OcDiskFindActiveMbrPartitionPath (
-                                  DevicePath,
-                                  &DevicePathSize
-                                  );
-    if (ActivePartitionDevicePath != NULL) {
-      DevicePath = ActivePartitionDevicePath;
-      Status     = gBS->LocateDevicePath (
-                          &gEfiBlockIoProtocolGuid,
-                          &ActivePartitionDevicePath,
-                          &FileSystemHandle
-                          );
-
-      if (!EFI_ERROR (Status)) {
-        IsLegacyEntry = TRUE;
-      }
-
-      //
-      // Expand BootCamp device path to EFI partition device path.
-      //
-    } else {
-      DevicePath = OcDiskFindSystemPartitionPath (
-                     DevicePath,
-                     &DevicePathSize,
-                     &FileSystemHandle
-                     );
-    }
+    RemainingDevicePath = DevicePath;
+    DevicePath          = OcDiskFindSystemPartitionPath (
+                            DevicePath,
+                            &DevicePathSize,
+                            &FileSystemHandle
+                            );
 
     FreePool (RemainingDevicePath);
 
@@ -1470,9 +1342,8 @@ AddBootEntryFromBootOption (
     }
 
     //
-    // The Device Path returned by OcDiskFindActiveMbrPartitionPath() and
-    // OcDiskFindSystemPartitionPath() is a pointer to an installed protocol.
-    // Duplicate it so we own the memory.
+    // The Device Path returned by OcDiskFindSystemPartitionPath() is a pointer
+    // to an installed protocol. Duplicate it so we own the memory.
     //
     if (DevicePath != NULL) {
       DevicePath = AllocateCopyPool (DevicePathSize, DevicePath);
@@ -1695,39 +1566,32 @@ AddBootEntryFromBootOption (
     FreePool (DevicePath);
   }
 
-  if (IsLegacyEntry) {
-    Status = AddBootEntryFromLegacyPartition (
-               BootContext,
-               FileSystem
-               );
-  } else {
-    //
-    // We may have a Boot#### entry pointing to macOS with full DP (up to boot.efi),
-    // so IsRoot will be true. However, if this is APFS, we may still have:
-    // - Recovery for this macOS.
-    // - Another macOS installation.
-    // We can only detect them with bless, so we invoke bless in deduplication mode.
-    // We also detect only the Core Apple Boot Policy predefined booter paths to
-    // avoid detection of e.g. generic booters (such as BOOTx64) to avoid
-    // duplicates.
-    //
-    // The amount of paths depends on the kind of the entry.
-    // - If this is a root entry (i.e. it points to the partition)
-    //   we invoke full bless, as it may be Windows entry created by legacy NVRAM script.
-    // - If this is a full entry (i.e. it points to the bootloader)
-    //   we invoke partial bless, which ignores BOOTx64.efi.
-    //   Ignoring BOOTx64.efi is important as we may already have bootmgfw.efi as our entry,
-    //   and we do not want to see Windows added twice.
-    //
-    Status = AddBootEntryFromBless (
-               BootContext,
-               FileSystem,
-               gAppleBootPolicyPredefinedPaths,
-               IsRoot ? gAppleBootPolicyNumPredefinedPaths : gAppleBootPolicyCoreNumPredefinedPaths,
-               LazyScan,
-               TRUE
-               );
-  }
+  //
+  // We may have a Boot#### entry pointing to macOS with full DP (up to boot.efi),
+  // so IsRoot will be true. However, if this is APFS, we may still have:
+  // - Recovery for this macOS.
+  // - Another macOS installation.
+  // We can only detect them with bless, so we invoke bless in deduplication mode.
+  // We also detect only the Core Apple Boot Policy predefined booter paths to
+  // avoid detection of e.g. generic booters (such as BOOTx64) to avoid
+  // duplicates.
+  //
+  // The amount of paths depends on the kind of the entry.
+  // - If this is a root entry (i.e. it points to the partition)
+  //   we invoke full bless, as it may be Windows entry created by legacy NVRAM script.
+  // - If this is a full entry (i.e. it points to the bootloader)
+  //   we invoke partial bless, which ignores BOOTx64.efi.
+  //   Ignoring BOOTx64.efi is important as we may already have bootmgfw.efi as our entry,
+  //   and we do not want to see Windows added twice.
+  //
+  Status = AddBootEntryFromBless (
+             BootContext,
+             FileSystem,
+             gAppleBootPolicyPredefinedPaths,
+             IsRoot ? gAppleBootPolicyNumPredefinedPaths : gAppleBootPolicyCoreNumPredefinedPaths,
+             LazyScan,
+             TRUE
+             );
 
   return Status;
 }
@@ -1745,10 +1609,9 @@ AddBootEntryFromBootOption (
 STATIC
 EFI_STATUS
 AddFileSystemEntry (
-  IN OUT OC_BOOT_CONTEXT    *BootContext,
-  IN     EFI_HANDLE         FileSystemHandle,
-  IN     OC_LEGACY_OS_TYPE  LegacyOsType,
-  OUT OC_BOOT_FILESYSTEM    **FileSystemEntry  OPTIONAL
+  IN OUT OC_BOOT_CONTEXT  *BootContext,
+  IN     EFI_HANDLE       FileSystemHandle,
+  OUT OC_BOOT_FILESYSTEM  **FileSystemEntry  OPTIONAL
   )
 {
   EFI_STATUS                Status;
@@ -1762,7 +1625,6 @@ AddFileSystemEntry (
   Status = InternalCheckScanPolicy (
              FileSystemHandle,
              BootContext->PickerContext->ScanPolicy,
-             LegacyOsType != OcLegacyOsTypeNone,
              &IsExternal
              );
 
@@ -1783,11 +1645,10 @@ AddFileSystemEntry (
 
   DEBUG ((
     DEBUG_INFO,
-    "OCB: Adding fs %p (E:%d|L:%d|B:%d|P:%r) - %s\n",
+    "OCB: Adding fs %p (E:%d|L:%d|P:%r) - %s\n",
     FileSystemHandle,
     IsExternal,
     LoaderFs,
-    LegacyOsType,
     Status,
     OC_HUMAN_STRING (TextDevicePath)
     ));
@@ -1812,7 +1673,6 @@ AddFileSystemEntry (
   Entry->RecoveryFs      = NULL;
   Entry->External        = IsExternal;
   Entry->LoaderFs        = LoaderFs;
-  Entry->LegacyOsType    = LegacyOsType;
   Entry->HasSelfRecovery = FALSE;
   InsertTailList (&BootContext->FileSystems, &Entry->Link);
   ++BootContext->FileSystemCount;
@@ -1956,7 +1816,7 @@ InternalFileSystemForHandle (
     return NULL;
   }
 
-  Status = AddFileSystemEntry (BootContext, FileSystemHandle, FALSE, &FileSystem);
+  Status = AddFileSystemEntry (BootContext, FileSystemHandle, &FileSystem);
   if (!EFI_ERROR (Status)) {
     return FileSystem;
   }
@@ -1971,12 +1831,11 @@ BuildFileSystemList (
   IN BOOLEAN            Empty
   )
 {
-  OC_BOOT_CONTEXT    *BootContext;
-  EFI_STATUS         Status;
-  OC_LEGACY_OS_TYPE  LegacyOsType;
-  UINTN              NoHandles;
-  EFI_HANDLE         *Handles;
-  UINTN              Index;
+  OC_BOOT_CONTEXT  *BootContext;
+  EFI_STATUS       Status;
+  UINTN            NoHandles;
+  EFI_HANDLE       *Handles;
+  UINTN            Index;
 
   BootContext = AllocatePool (sizeof (*BootContext));
   if (BootContext == NULL) {
@@ -1999,9 +1858,6 @@ BuildFileSystemList (
     return BootContext;
   }
 
-  //
-  // Add readable filesystems.
-  //
   Status = gBS->LocateHandleBuffer (
                   ByProtocol,
                   &gEfiSimpleFileSystemProtocolGuid,
@@ -2017,45 +1873,11 @@ BuildFileSystemList (
     AddFileSystemEntry (
       BootContext,
       Handles[Index],
-      FALSE,
       NULL
       );
   }
 
   FreePool (Handles);
-
-  //
-  // Add legacy partitions with valid boot sectors if on a supported legacy platform.
-  //
-  if (Context->LegacyBootType != OcLegacyBootTypeNone) {
-    Status = gBS->LocateHandleBuffer (
-                    ByProtocol,
-                    &gEfiBlockIoProtocolGuid,
-                    NULL,
-                    &NoHandles,
-                    &Handles
-                    );
-    if (EFI_ERROR (Status)) {
-      return BootContext;
-    }
-
-    for (Index = 0; Index < NoHandles; ++Index) {
-      LegacyOsType = InternalGetPartitionLegacyOsType (Handles[Index]);
-      if (LegacyOsType == OcLegacyOsTypeNone) {
-        continue;
-      }
-
-      AddFileSystemEntry (
-        BootContext,
-        Handles[Index],
-        LegacyOsType,
-        NULL
-        );
-    }
-
-    FreePool (Handles);
-  }
-
   return BootContext;
 }
 
@@ -2258,40 +2080,28 @@ OcScanForBootEntries (
   {
     FileSystem = BASE_CR (Link, OC_BOOT_FILESYSTEM, Link);
 
-    if (FileSystem->LegacyOsType != OcLegacyOsTypeNone) {
-      //
-      // Process legacy boot partition.
-      //
-      if (IsListEmpty (&FileSystem->BootEntries)) {
-        AddBootEntryFromLegacyPartition (
-          BootContext,
-          FileSystem
-          );
-      }
-    } else {
-      PartitionEntry                  = OcGetGptPartitionEntry (FileSystem->Handle);
-      IsDefaultEntryProtocolPartition = (
-                                           (DefaultEntryId != NULL)
-                                        && CompareGuid (
-                                             &DefaultEntryPartuuid,
-                                             (PartitionEntry == NULL) ? &gEfiPartTypeUnusedGuid : &PartitionEntry->UniquePartitionGUID
-                                             )
-                                           );
+    PartitionEntry                  = OcGetGptPartitionEntry (FileSystem->Handle);
+    IsDefaultEntryProtocolPartition = (
+                                         (DefaultEntryId != NULL)
+                                      && CompareGuid (
+                                           &DefaultEntryPartuuid,
+                                           (PartitionEntry == NULL) ? &gEfiPartTypeUnusedGuid : &PartitionEntry->UniquePartitionGUID
+                                           )
+                                         );
 
-      //
-      // No entries, or only entry pre-created from boot entry protocol,
-      // so process this directory with Apple Bless.
-      //
-      if (IsDefaultEntryProtocolPartition || IsListEmpty (&FileSystem->BootEntries)) {
-        AddBootEntryFromBless (
-          BootContext,
-          FileSystem,
-          gAppleBootPolicyPredefinedPaths,
-          gAppleBootPolicyNumPredefinedPaths,
-          FALSE,
-          FALSE
-          );
-      }
+    //
+    // No entries, or only entry pre-created from boot entry protocol,
+    // so process this directory with Apple Bless.
+    //
+    if (IsDefaultEntryProtocolPartition || IsListEmpty (&FileSystem->BootEntries)) {
+      AddBootEntryFromBless (
+        BootContext,
+        FileSystem,
+        gAppleBootPolicyPredefinedPaths,
+        gAppleBootPolicyNumPredefinedPaths,
+        FALSE,
+        FALSE
+        );
     }
 
     //
@@ -2633,7 +2443,7 @@ OcLoadBootEntry (
 
   if ((BootEntry->Type & OC_BOOT_SYSTEM) != 0) {
     ASSERT (BootEntry->SystemAction != NULL);
-    return BootEntry->SystemAction (Context);
+    return BootEntry->SystemAction (Context, BootEntry->SystemActionContext);
   }
 
   Status = InternalLoadBootEntry (
diff --git a/Library/OcBootManagementLib/BootManagementInternal.h b/Library/OcBootManagementLib/BootManagementInternal.h
index 2d3e0ba6f6d..1a3ac19387a 100644
--- a/Library/OcBootManagementLib/BootManagementInternal.h
+++ b/Library/OcBootManagementLib/BootManagementInternal.h
@@ -124,28 +124,10 @@ typedef enum {
   BootEntryDisabled,
 } INTERNAL_ENTRY_VISIBILITY;
 
-EFI_STATUS
-InternalLoadAppleLegacyInterface (
-  IN  EFI_HANDLE                ParentImageHandle,
-  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath,
-  OUT EFI_HANDLE                *ImageHandle
-  );
-
-OC_LEGACY_OS_TYPE
-InternalGetPartitionLegacyOsType (
-  IN  EFI_HANDLE  PartitionHandle
-  );
-
-OC_LEGACY_BOOT_TYPE
-InternalGetLegacyBootType (
-  VOID
-  );
-
 EFI_STATUS
 InternalCheckScanPolicy (
   IN  EFI_HANDLE  Handle,
   IN  UINT32      Policy,
-  IN  BOOLEAN     Legacy,
   OUT BOOLEAN     *External OPTIONAL
   );
 
@@ -251,22 +233,6 @@ InternalDescribeBootEntry (
   IN OUT OC_BOOT_ENTRY    *BootEntry
   );
 
-/**
-  Describe legacy boot entry contents by setting fields other than DevicePath.
-
-  @param[in]      BootContext   Boot context.
-  @param[in]      LegacyOsType  Legacy OS type.
-  @param[in,out]  BootEntry     Located boot entry.
-
-  @retval EFI_SUCCESS   The entry point is described successfully.
-**/
-EFI_STATUS
-InternalDescribeLegacyBootEntry (
-  IN     OC_BOOT_CONTEXT    *BootContext,
-  IN     OC_LEGACY_OS_TYPE  LegacyOsType,
-  IN OUT OC_BOOT_ENTRY      *BootEntry
-  );
-
 BOOLEAN
 InternalIsAppleLegacyLoadApp (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
diff --git a/Library/OcBootManagementLib/DefaultEntryChoice.c b/Library/OcBootManagementLib/DefaultEntryChoice.c
index 52937a7217f..5c118fc072f 100644
--- a/Library/OcBootManagementLib/DefaultEntryChoice.c
+++ b/Library/OcBootManagementLib/DefaultEntryChoice.c
@@ -1577,27 +1577,14 @@ InternalLoadBootEntry (
 
   DEBUG_CODE_END ();
 
-  if (BootEntry->LegacyOsType != OcLegacyOsTypeNone) {
-    if (Context->LegacyBootType == OcLegacyBootTypeApple) {
-      Status = InternalLoadAppleLegacyInterface (
-                 ParentHandle,
-                 DevicePath,
-                 EntryHandle
-                 );
-    } else {
-      DEBUG ((DEBUG_INFO, "OCB: Unsupported legacy interface type: %u\n", Context->LegacyBootType));
-      Status = EFI_UNSUPPORTED;
-    }
-  } else {
-    Status = gBS->LoadImage (
-                    FALSE,
-                    ParentHandle,
-                    DevicePath,
-                    EntryData,
-                    EntryDataSize,
-                    EntryHandle
-                    );
-  }
+  Status = gBS->LoadImage (
+                  FALSE,
+                  ParentHandle,
+                  DevicePath,
+                  EntryData,
+                  EntryDataSize,
+                  EntryHandle
+                  );
 
   if (EntryData != NULL) {
     FreePool (EntryData);
diff --git a/Library/OcBootManagementLib/OcBootManagementLib.c b/Library/OcBootManagementLib/OcBootManagementLib.c
index 85963549bb2..b1d778226fa 100644
--- a/Library/OcBootManagementLib/OcBootManagementLib.c
+++ b/Library/OcBootManagementLib/OcBootManagementLib.c
@@ -324,11 +324,6 @@ OcRunBootPicker (
     Context->HideAuxiliary = FALSE;
   }
 
-  //
-  // Get legacy boot mode.
-  //
-  Context->LegacyBootType = InternalGetLegacyBootType ();
-
   while (TRUE) {
     //
     // Never show Apple Picker twice, re-scan for entries if we previously successfully showed it.
diff --git a/Library/OcBootManagementLib/OcBootManagementLib.inf b/Library/OcBootManagementLib/OcBootManagementLib.inf
index 42efff2e8e2..efb5743b9a3 100644
--- a/Library/OcBootManagementLib/OcBootManagementLib.inf
+++ b/Library/OcBootManagementLib/OcBootManagementLib.inf
@@ -45,7 +45,6 @@
   DmgBootSupport.c
   HotKeySupport.c
   ImageLoader.c
-  LegacyBootSupport.c
   PolicyManagement.c
   OcBootManagementLib.c
 
@@ -53,7 +52,6 @@
   OpenCorePkg/OpenCorePkg.dec
   MdePkg/MdePkg.dec
   MdeModulePkg/MdeModulePkg.dec
-  OvmfPkg/OvmfPkg.dec
   UefiCpuPkg/UefiCpuPkg.dec
 
 [Guids]
@@ -86,7 +84,6 @@
   gAppleBeepGenProtocolGuid                     ## SOMETIMES_CONSUMES
   gOcBootEntryProtocolGuid                      ## CONSUMES
   gAppleFirmwareUserInterfaceProtocolGuid       ## SOMETIMES_CONSUMES
-  gEfiLegacy8259ProtocolGuid                    ## SOMETIMES_CONSUMES
 
 [LibraryClasses]
   BaseLib
diff --git a/Library/OcBootManagementLib/PolicyManagement.c b/Library/OcBootManagementLib/PolicyManagement.c
index 61d5e9c69b8..a19faaab915 100644
--- a/Library/OcBootManagementLib/PolicyManagement.c
+++ b/Library/OcBootManagementLib/PolicyManagement.c
@@ -299,7 +299,6 @@ EFI_STATUS
 InternalCheckScanPolicy (
   IN  EFI_HANDLE  Handle,
   IN  UINT32      Policy,
-  IN  BOOLEAN     Legacy,
   OUT BOOLEAN     *External OPTIONAL
   )
 {
@@ -315,7 +314,7 @@ InternalCheckScanPolicy (
     return EFI_SECURITY_VIOLATION;
   }
 
-  if (!Legacy && ((Policy & OC_SCAN_FILE_SYSTEM_LOCK) != 0)) {
+  if ((Policy & OC_SCAN_FILE_SYSTEM_LOCK) != 0) {
     FileSystemPolicy = OcGetFileSystemPolicyType (Handle);
 
     if ((Policy & FileSystemPolicy) == 0) {
diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index bc3422ae844..bdacfa3e1dc 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -23,6 +23,33 @@
 #include <Protocol/PciIo.h>
 #include <Protocol/Timer.h>
 
+//
+// 8254 Timer registers
+//
+#define TIMER0_COUNT_PORT    0x40
+#define TIMER1_COUNT_PORT    0x41
+#define TIMER2_COUNT_PORT    0x42
+#define TIMER_CONTROL_PORT   0x43
+#define TIMER0_CONTROL_WORD  0x36
+
+//
+// Vector base definitions
+//
+//
+// 8259 Hardware definitions
+//
+#define LEGACY_MODE_BASE_VECTOR_MASTER  0x08
+#define LEGACY_MODE_BASE_VECTOR_SLAVE   0x70
+
+//
+// The original PC used INT8-F for master PIC. Since these mapped over
+// processor exceptions TIANO moved the master PIC to INT68-6F.
+//
+// The vector base for slave PIC is set as 0x70 for PC-AT compatibility.
+//
+#define PROTECTED_MODE_BASE_VECTOR_MASTER  0x68
+#define PROTECTED_MODE_BASE_VECTOR_SLAVE   0x70
+
 /**
   Initialize legacy environment for BIOS INI caller.
 
@@ -295,3 +322,150 @@ OcLegacyThunkBiosInt86 (
 
   return Ret;
 }
+
+BOOLEAN
+EFIAPI
+OcLegacyThunkFarCall86 (
+  IN  THUNK_CONTEXT             *ThunkContext,
+  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN  UINT16                    Segment,
+  IN  UINT16                    Offset,
+  IN  IA32_REGISTER_SET         *Regs,
+  IN  VOID                      *Stack,
+  IN  UINTN                     StackSize
+  )
+{
+  UINTN              Status;
+  UINT16             *Stack16;
+  IA32_REGISTER_SET  ThunkRegSet;
+  BOOLEAN            Ret;
+  // BOOLEAN               InterruptState;
+  UINT64   TimerPeriod;
+  BOOLEAN  Enabled;
+
+  EFI_TIMER_ARCH_PROTOCOL  *TimerProtocol;
+
+  ZeroMem (&ThunkRegSet, sizeof (ThunkRegSet));
+  ThunkRegSet.E.EFLAGS.Bits.Reserved_0 = 1;
+  ThunkRegSet.E.EFLAGS.Bits.Reserved_1 = 0;
+  ThunkRegSet.E.EFLAGS.Bits.Reserved_2 = 0;
+  ThunkRegSet.E.EFLAGS.Bits.Reserved_3 = 0;
+  ThunkRegSet.E.EFLAGS.Bits.IOPL       = 3;
+  ThunkRegSet.E.EFLAGS.Bits.NT         = 0;
+  ThunkRegSet.E.EFLAGS.Bits.IF         = 1;
+  ThunkRegSet.E.EFLAGS.Bits.TF         = 0;
+  ThunkRegSet.E.EFLAGS.Bits.CF         = 0;
+
+  ThunkRegSet.E.EDI = Regs->E.EDI;
+  ThunkRegSet.E.ESI = Regs->E.ESI;
+  ThunkRegSet.E.EBP = Regs->E.EBP;
+  ThunkRegSet.E.EBX = Regs->E.EBX;
+  ThunkRegSet.E.EDX = Regs->E.EDX;
+  ThunkRegSet.E.ECX = Regs->E.ECX;
+  ThunkRegSet.E.EAX = Regs->E.EAX;
+  ThunkRegSet.E.DS  = Regs->E.DS;
+  ThunkRegSet.E.ES  = Regs->E.ES;
+
+  //
+  // The call to Legacy16 is a critical section to EFI
+  //
+  Enabled = SaveAndDisableInterrupts ();
+
+  //
+  // Save current rate of DXE timer and disable it
+  // while executing in real mode.
+  //
+  Status = gBS->LocateProtocol (
+                  &gEfiTimerArchProtocolGuid,
+                  NULL,
+                  (VOID **)&TimerProtocol
+                  );
+  if (EFI_ERROR (Status)) {
+    TimerProtocol->GetTimerPeriod (TimerProtocol, &TimerPeriod);
+    TimerProtocol->SetTimerPeriod (TimerProtocol, 0);
+  }
+
+  //
+  // Reset timer to default legacy rate of 54.9254.
+  //
+  IoWrite8 (TIMER_CONTROL_PORT, TIMER0_CONTROL_WORD);
+  IoWrite8 (TIMER0_COUNT_PORT, 0x00);
+  IoWrite8 (TIMER0_COUNT_PORT, 0x00);
+
+  //
+  // Put the 8259 into its legacy mode by reprogramming the vector bases
+  //
+  Status = Legacy8259->SetVectorBase (Legacy8259, LEGACY_MODE_BASE_VECTOR_MASTER, LEGACY_MODE_BASE_VECTOR_SLAVE);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
+  //
+  Status = Legacy8259->SetMode (Legacy8259, Efi8259LegacyMode, NULL, NULL);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Clear the error flag; thunk code may set it. Stack16 should be the high address
+  // Make Statk16 address the low 16 bit must be not zero.
+  //
+  Stack16 = (UINT16 *)((UINT8 *)ThunkContext->RealModeBuffer + ThunkContext->RealModeBufferSize - sizeof (UINT16));
+
+  if ((Stack != NULL) && (StackSize != 0)) {
+    //
+    // Copy Stack to low memory stack
+    //
+    Stack16 -= StackSize / sizeof (UINT16);
+    CopyMem (Stack16, Stack, StackSize);
+  }
+
+  ThunkRegSet.E.SS  = (UINT16)(((UINTN)Stack16 >> 16) << 12);
+  ThunkRegSet.E.ESP = (UINT16)(UINTN)Stack16;
+  ThunkRegSet.E.CS  = Segment;
+  ThunkRegSet.E.Eip = Offset;
+
+  ThunkContext->RealModeState = &ThunkRegSet;
+  AsmThunk16 (ThunkContext);
+
+  if ((Stack != NULL) && (StackSize != 0)) {
+    //
+    // Copy low memory stack to Stack
+    //
+    CopyMem (Stack, Stack16, StackSize);
+  }
+
+  //
+  // Restore protected mode interrupt state
+  //
+  Status = Legacy8259->SetMode (Legacy8259, Efi8259ProtectedMode, NULL, NULL);
+  ASSERT_EFI_ERROR (Status);
+
+  ThunkContext->RealModeState = NULL;
+
+  //
+  // Enable and restore rate of DXE Timer
+  //
+  // Private->Timer->SetTimerPeriod (Private->Timer, TimerPeriod);
+
+  //
+  // End critical section
+  //
+  SetInterruptState (Enabled);
+
+  Regs->E.EDI = ThunkRegSet.E.EDI;
+  Regs->E.ESI = ThunkRegSet.E.ESI;
+  Regs->E.EBP = ThunkRegSet.E.EBP;
+  Regs->E.EBX = ThunkRegSet.E.EBX;
+  Regs->E.EDX = ThunkRegSet.E.EDX;
+  Regs->E.ECX = ThunkRegSet.E.ECX;
+  Regs->E.EAX = ThunkRegSet.E.EAX;
+  Regs->E.SS  = ThunkRegSet.E.SS;
+  Regs->E.CS  = ThunkRegSet.E.CS;
+  Regs->E.DS  = ThunkRegSet.E.DS;
+  Regs->E.ES  = ThunkRegSet.E.ES;
+
+  CopyMem (&(Regs->E.EFLAGS), &(ThunkRegSet.E.EFLAGS), sizeof (UINT32));
+
+  Ret = (BOOLEAN)(Regs->E.EFLAGS.Bits.CF == 1);
+
+  return Ret;
+}
diff --git a/OpenCorePkg.dsc b/OpenCorePkg.dsc
index 01552ceeeae..4aba7840a8d 100755
--- a/OpenCorePkg.dsc
+++ b/OpenCorePkg.dsc
@@ -299,6 +299,7 @@
   OpenCorePkg/Legacy/BootPlatform/BiosVideo/BiosVideo.inf
   OpenCorePkg/Platform/CrScreenshotDxe/CrScreenshotDxe.inf
   OpenCorePkg/Platform/OpenCanopy/OpenCanopy.inf
+  OpenCorePkg/Platform/OpenLegacyBoot/OpenLegacyBoot.inf
   OpenCorePkg/Platform/OpenLinuxBoot/OpenLinuxBoot.inf
   OpenCorePkg/Platform/OpenNtfsDxe/OpenNtfsDxe.inf
   OpenCorePkg/Platform/OpenPartitionDxe/PartitionDxe.inf
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
new file mode 100644
index 00000000000..4bb6d1dceb2
--- /dev/null
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -0,0 +1,44 @@
+/** @file
+  Copyright (C) 2023, Goldfish64. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-3-Clause
+**/
+
+#ifndef LEGACY_BOOT_INTERNAL_H
+#define LEGACY_BOOT_INTERNAL_H
+
+extern EFI_HANDLE  gImageHandle;
+extern BOOLEAN     gIsAppleInterfaceSupported;
+
+/**
+  Legacy operating system type.
+**/
+typedef enum OC_LEGACY_OS_TYPE_ {
+  OcLegacyOsTypeNone,
+  OcLegacyOsTypeWindowsNtldr,
+  OcLegacyOsTypeWindowsBootmgr,
+  OcLegacyOsTypeIsoLinux
+} OC_LEGACY_OS_TYPE;
+
+EFI_STATUS
+InternalIsLegacyInterfaceSupported (
+  OUT BOOLEAN  *IsAppleInterfaceSupported
+  );
+
+EFI_STATUS
+InternalLoadAppleLegacyInterface (
+  IN  EFI_HANDLE                ParentImageHandle,
+  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath,
+  OUT EFI_HANDLE                *ImageHandle
+  );
+
+OC_LEGACY_OS_TYPE
+InternalGetPartitionLegacyOsType (
+  IN  EFI_HANDLE  PartitionHandle
+  );
+
+EFI_STATUS
+InternalLoadLegacyMbr (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
+  );
+
+#endif // LEGACY_BOOT_INTERNAL_H
diff --git a/Library/OcBootManagementLib/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
similarity index 78%
rename from Library/OcBootManagementLib/LegacyBootSupport.c
rename to Platform/OpenLegacyBoot/LegacyBootSupport.c
index 985fc620a74..1de67a5edc2 100644
--- a/Library/OcBootManagementLib/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -1,18 +1,9 @@
 /** @file
-  Copyright (C) 2023, Goldfish64. All rights reserved.
-
-  All rights reserved.
-
-  This program and the accompanying materials
-  are licensed and made available under the terms and conditions of the BSD License
-  which accompanies this distribution.  The full text of the license may be found at
-  http://opensource.org/licenses/bsd-license.php
-
-  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
-  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+  Copyright (C) 2023, Goldfish64. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-3-Clause
 **/
 
-#include "BootManagementInternal.h"
+#include "LegacyBootInternal.h"
 
 #include <IndustryStandard/Mbr.h>
 
@@ -20,11 +11,12 @@
 #include <Library/BaseMemoryLib.h>
 #include <Library/DevicePathLib.h>
 #include <Library/MemoryAllocationLib.h>
+#include <Library/OcBootManagementLib.h>
 #include <Library/OcDebugLogLib.h>
 #include <Library/OcDevicePathLib.h>
 #include <Library/OcFileLib.h>
+#include <Library/OcLegacyThunkLib.h>
 #include <Library/OcMiscLib.h>
-#include <Library/PrintLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/UefiLib.h>
 #include <Library/UefiRuntimeServicesTableLib.h>
@@ -32,6 +24,8 @@
 #include <Protocol/DevicePath.h>
 #include <Protocol/Legacy8259.h>
 
+THUNK_CONTEXT  mThunkContext;
+
 //
 // PIWG firmware media device path for Apple legacy interface.
 // FwFile(2B0585EB-D8B8-49A9-8B8CE21B01AEF2B7)
@@ -45,7 +39,7 @@ static CONST EFI_DEVICE_PATH_PROTOCOL  *AppleLegacyInterfaceMediaDevicePathPath
 
 #define MAX_APPLE_LEGACY_DEVICE_PATHS  16
 
-STATIC
+// STATIC
 BOOLEAN
 CheckLegacySignature (
   IN CONST CHAR8         *SignatureStr,
@@ -157,6 +151,34 @@ ScanAppleLegacyInterfacePaths (
   return EFI_SUCCESS;
 }
 
+EFI_STATUS
+InternalIsLegacyInterfaceSupported (
+  OUT BOOLEAN  *IsAppleInterfaceSupported
+  )
+{
+  EFI_STATUS                Status;
+  EFI_LEGACY_8259_PROTOCOL  *Legacy8259;
+
+  ASSERT (IsAppleInterfaceSupported != NULL);
+
+  //
+  // Apple legacy boot interface is only available on Apple platforms.
+  // Use legacy 16-bit thunks on legacy PC platforms.
+  //
+  if (OcStriCmp (L"Apple", gST->FirmwareVendor) == 0) {
+    *IsAppleInterfaceSupported = TRUE;
+    return EFI_SUCCESS;
+  } else {
+    Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **)&Legacy8259);
+    if (!EFI_ERROR (Status) && (Legacy8259 != NULL)) {
+      *IsAppleInterfaceSupported = FALSE;
+      return EFI_SUCCESS;
+    }
+  }
+
+  return EFI_UNSUPPORTED;
+}
+
 EFI_STATUS
 InternalLoadAppleLegacyInterface (
   IN  EFI_HANDLE                ParentImageHandle,
@@ -268,7 +290,7 @@ InternalGetPartitionLegacyOsType (
     return OcLegacyOsTypeNone;
   }
 
-  DebugPrintDevicePath (DEBUG_VERBOSE, "OCB: Reading MBR for disk", DevicePath);
+  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading MBR for disk", DevicePath);
 
   DiskHandle = OcPartitionGetDiskHandle (DevicePath);
   if (DiskHandle == NULL) {
@@ -277,7 +299,7 @@ InternalGetPartitionLegacyOsType (
 
   Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
   if (Mbr == NULL) {
-    DEBUG ((DEBUG_VERBOSE, "OCB: Disk does not contain a valid MBR partition table\n"));
+    DEBUG ((DEBUG_INFO, "OCB: Disk does not contain a valid MBR partition table\n"));
     return OcLegacyOsTypeNone;
   }
 
@@ -290,7 +312,7 @@ InternalGetPartitionLegacyOsType (
     //
     // Retrieve the first sector of the partition.
     //
-    DebugPrintDevicePath (DEBUG_VERBOSE, "OCB: Reading PBR for partition", DevicePath);
+    DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading PBR for partition", DevicePath);
     Status = OcDiskInitializeContext (
                &DiskContext,
                PartitionHandle,
@@ -351,28 +373,79 @@ InternalGetPartitionLegacyOsType (
   return LegacyOsType;
 }
 
-OC_LEGACY_BOOT_TYPE
-InternalGetLegacyBootType (
-  VOID
+EFI_STATUS
+InternalLoadLegacyMbr (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   )
 {
-  EFI_STATUS                Status;
+  EFI_STATUS          Status;
+  EFI_HANDLE          DiskHandle;
+  MASTER_BOOT_RECORD  *Mbr;
+  IA32_REGISTER_SET   Regs;
+  UINT8               *MbrPtr = (UINT8 *)0x7C00;
+
   EFI_LEGACY_8259_PROTOCOL  *Legacy8259;
-  OC_LEGACY_BOOT_TYPE       BootType;
 
   //
-  // Apple legacy boot interface is only available on Apple platforms.
-  // Use legacy 16-bit thunks on legacy PC platforms.
+  // Locate required protocols.
   //
-  BootType = OcLegacyBootTypeNone;
-  if (OcStriCmp (L"Apple", gST->FirmwareVendor) == 0) {
-    BootType = OcLegacyBootTypeApple;
-  } else {
-    Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **)&Legacy8259);
-    if (!EFI_ERROR (Status) && (Legacy8259 != NULL)) {
-      BootType = OcLegacyBootTypeLegacyBios;
-    }
+  Status = gBS->LocateProtocol (
+                  &gEfiLegacy8259ProtocolGuid,
+                  NULL,
+                  (VOID **)&Legacy8259
+                  );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_INFO, "OCB: Could not locate Legacy8259 protocol\n"));
+    return Status;
   }
 
-  return BootType;
+  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading MBR for disk", HdDevicePath);
+
+  DiskHandle = OcPartitionGetDiskHandle (HdDevicePath);
+  if (DiskHandle == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
+  if (Mbr == NULL) {
+    DEBUG ((DEBUG_INFO, "OCB: Disk does not contain a valid MBR partition table\n"));
+    return EFI_INVALID_PARAMETER;
+  }
+
+  //
+  // Create and initialize thunk structures.
+  //
+  Status = OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  Status = OcLegacyThunkInitializeInterruptRedirection (Legacy8259);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  DEBUG ((DEBUG_INFO, "OCB: Preparing to boot legacy system\n"));
+
+  OcLegacyThunkDisconnectEfiGraphics ();
+
+  CopyMem (MbrPtr, Mbr, sizeof (*Mbr));
+
+  ZeroMem (&Regs, sizeof (Regs));
+  Regs.X.DX = 0x82;
+  OcLegacyThunkFarCall86 (
+    &mThunkContext,
+    Legacy8259,
+    0,
+    0x7c00,
+    &Regs,
+    NULL,
+    0
+    );
+
+  DEBUG ((DEBUG_INFO, "here\n"));
+  while (TRUE) {
+  }
+
+  return EFI_SUCCESS;
 }
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
new file mode 100644
index 00000000000..e0fc59daa51
--- /dev/null
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -0,0 +1,277 @@
+/** @file
+  Legacy boot driver.
+
+  Copyright (c) 2023, Goldfish64. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-3-Clause
+**/
+
+#include "LegacyBootInternal.h"
+
+#include <Uefi.h>
+#include <Guid/Gpt.h>
+#include <Library/BaseLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/OcBootManagementLib.h>
+#include <Library/OcDebugLogLib.h>
+#include <Library/OcFileLib.h>
+#include <Library/OcFlexArrayLib.h>
+#include <Library/OcStringLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+
+#include <Protocol/OcBootEntry.h>
+
+EFI_HANDLE  gImageHandle;
+BOOLEAN     gIsAppleInterfaceSupported;
+
+VOID
+InternalFreePickerEntry (
+  IN   OC_PICKER_ENTRY  *Entry
+  )
+{
+  ASSERT (Entry != NULL);
+
+  if (Entry == NULL) {
+    return;
+  }
+
+  //
+  // TODO: Is this un-CONST casting okay?
+  // (Are they CONST because they are not supposed to be freed when used as before?)
+  //
+  if (Entry->Id != NULL) {
+    FreePool ((CHAR8 *)Entry->Id);
+  }
+
+  if (Entry->Name != NULL) {
+    FreePool ((CHAR8 *)Entry->Name);
+  }
+
+  if (Entry->Path != NULL) {
+    FreePool ((CHAR8 *)Entry->Path);
+  }
+
+  if (Entry->Arguments != NULL) {
+    FreePool ((CHAR8 *)Entry->Arguments);
+  }
+
+  if (Entry->Flavour != NULL) {
+    FreePool ((CHAR8 *)Entry->Flavour);
+  }
+}
+
+STATIC
+EFI_STATUS
+SystemActionDoLegacyBoot (
+  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
+  IN              VOID               *ActionContext
+  )
+{
+  EFI_STATUS                 Status;
+  EFI_HANDLE                 LoadedImageHandle;
+  EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
+  EFI_DEVICE_PATH_PROTOCOL   *DevicePath;
+
+  DevicePath = (EFI_DEVICE_PATH_PROTOCOL *)ActionContext;
+
+  if (gIsAppleInterfaceSupported) {
+    DebugPrintDevicePath (DEBUG_INFO, "LEG: Device path", DevicePath);
+
+    Status = InternalLoadAppleLegacyInterface (
+               gImageHandle,
+               DevicePath,
+               &LoadedImageHandle
+               );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_WARN, "LEG: Failure while loading Apple legacy interface - %r\n", Status));
+      return Status;
+    }
+
+    Status = gBS->HandleProtocol (
+                    LoadedImageHandle,
+                    &gEfiLoadedImageProtocolGuid,
+                    (VOID **)&LoadedImage
+                    );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_WARN, "LEG: Failure while loading Apple legacy interface - %r\n", Status));
+      return Status;
+    }
+
+    LoadedImage->LoadOptionsSize = 0;
+    LoadedImage->LoadOptions     = NULL;
+
+    CONST CHAR8  *Args;
+
+    Args = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
+
+    OcAppendArgumentsToLoadedImage (LoadedImage, &Args, 1, TRUE);
+    DEBUG ((
+      DEBUG_INFO,
+      "OCB: Args <%s>\n",
+      LoadedImage->LoadOptions
+      ));
+    Status = gBS->StartImage (LoadedImageHandle, NULL, NULL);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_WARN, "LEG: Failure while starting Apple legacy interface - %r\n", Status));
+      return Status;
+    }
+  }
+
+  return EFI_SUCCESS;
+}
+
+STATIC
+EFI_STATUS
+EFIAPI
+OcGetLegacyBootEntries (
+  IN OUT         OC_PICKER_CONTEXT  *PickerContext,
+  IN     CONST EFI_HANDLE           Device OPTIONAL,
+  OUT       OC_PICKER_ENTRY         **Entries,
+  OUT       UINTN                   *NumEntries
+  )
+{
+  // EFI_STATUS                       Status;
+  // EFI_SIMPLE_FILE_SYSTEM_PROTOCOL  *FileSystem;
+  // EFI_FILE_PROTOCOL                *RootDirectory;
+  // UINT32                           FileSystemPolicy;
+
+  OC_LEGACY_OS_TYPE  LegacyType;
+  OC_PICKER_ENTRY    *PickerEntry;
+
+  //
+  // No custom entries.
+  //
+  if (Device == NULL) {
+    return EFI_NOT_FOUND;
+  }
+
+  //
+  // Open partition file system.
+  //
+
+  /* Status = gBS->HandleProtocol (
+                   Device,
+                   &gEfiSimpleFileSystemProtocolGuid,
+                   (VOID **)&FileSystem
+                   );
+   if (EFI_ERROR (Status)) {
+     DEBUG ((DEBUG_WARN, "LEG: Missing filesystem - %r\n", Status));
+     return Status;
+   }
+
+   //
+   // Get handle to partiton root directory.
+   //
+   Status = FileSystem->OpenVolume (
+                          FileSystem,
+                          &RootDirectory
+                          );
+   if (EFI_ERROR (Status)) {
+     DEBUG ((DEBUG_WARN, "LEG: Invalid root volume - %r\n", Status));
+     return Status;
+   }
+
+   FileSystemPolicy = OcGetFileSystemPolicyType (Device);*/
+
+  //
+  // Disallow all but NTFS filesystems.
+  //
+  // if ((FileSystemPolicy & OC_SCAN_ALLOW_FS_NTFS) != 0) {
+  //   DEBUG ((DEBUG_INFO, "LEG: Not scanning non-NTFS filesystem\n"));
+  //  Status = EFI_NOT_FOUND;
+  // }
+
+  //
+  // Scan for boot entry (only one entry per filesystem).
+  //
+  LegacyType = InternalGetPartitionLegacyOsType (Device);
+  // RootDirectory->Close (RootDirectory);
+  if (LegacyType == OcLegacyOsTypeNone) {
+    return EFI_NOT_FOUND;
+  }
+
+  PickerEntry                      = AllocateZeroPool (sizeof (*PickerEntry));
+  PickerEntry->Id                  = "legacy_boot";
+  PickerEntry->Name                = "Windows (legacy)";
+  PickerEntry->Path                = NULL;
+  PickerEntry->Arguments           = NULL;
+  PickerEntry->Flavour             = OC_FLAVOUR_WINDOWS;
+  PickerEntry->Tool                = FALSE;
+  PickerEntry->TextMode            = TRUE;
+  PickerEntry->RealPath            = FALSE;
+  PickerEntry->SystemAction        = SystemActionDoLegacyBoot;
+  PickerEntry->SystemActionContext = DevicePathFromHandle (Device);
+
+  *Entries    = PickerEntry;
+  *NumEntries = 1;
+
+  return EFI_SUCCESS;
+}
+
+STATIC
+VOID
+EFIAPI
+OcFreeLegacyBootEntries (
+  IN   OC_PICKER_ENTRY  **Entries,
+  IN   UINTN            NumEntries
+  )
+{
+  return;
+  UINTN  Index;
+
+  ASSERT (Entries   != NULL);
+  ASSERT (*Entries  != NULL);
+  if ((Entries == NULL) || (*Entries == NULL)) {
+    return;
+  }
+
+  for (Index = 0; Index < NumEntries; Index++) {
+    InternalFreePickerEntry (&(*Entries)[Index]);
+  }
+
+  FreePool (*Entries);
+  *Entries = NULL;
+}
+
+STATIC
+OC_BOOT_ENTRY_PROTOCOL
+  mLegacyBootEntryProtocol = {
+  OC_BOOT_ENTRY_PROTOCOL_REVISION,
+  OcGetLegacyBootEntries,
+  OcFreeLegacyBootEntries,
+  NULL
+};
+
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  EFI_STATUS  Status;
+
+  gImageHandle = ImageHandle;
+
+  Status = InternalIsLegacyInterfaceSupported (&gIsAppleInterfaceSupported);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_WARN, "LEG: Legacy boot interface is supported on this system\n"));
+    return Status;
+  }
+
+  DEBUG ((DEBUG_INFO, "LEG: Apple legacy interface: %d\n", gIsAppleInterfaceSupported));
+
+  Status = gBS->InstallMultipleProtocolInterfaces (
+                  &ImageHandle,
+                  &gOcBootEntryProtocolGuid,
+                  &mLegacyBootEntryProtocol,
+                  NULL
+                  );
+
+  ASSERT_EFI_ERROR (Status);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  return EFI_SUCCESS;
+}
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.inf b/Platform/OpenLegacyBoot/OpenLegacyBoot.inf
new file mode 100644
index 00000000000..80da3de5fdd
--- /dev/null
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.inf
@@ -0,0 +1,44 @@
+## @file
+#  Legacy boot entry protocol implementation.
+#
+#  Copyright (C) 2023, Goldfish64. All rights reserved.<BR>
+#  SPDX-License-Identifier: BSD-3-Clause
+##
+
+
+[Defines]
+  INF_VERSION    = 0x00010005
+  BASE_NAME      = OpenLegacyBoot
+  ENTRY_POINT    = UefiMain
+  FILE_GUID      = 4BE5FC32-9434-4799-9F8F-ECD579025074
+  MODULE_TYPE    = UEFI_DRIVER
+  VERSION_STRING = 1.0
+
+[Packages]
+  OpenCorePkg/OpenCorePkg.dec
+  MdePkg/MdePkg.dec
+  MdeModulePkg/MdeModulePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[Guids]
+  gAppleLegacyLoadAppFileGuid         ## SOMETIMES_CONSUMES
+
+[LibraryClasses]
+  DebugLib
+  OcBootManagementLib
+  OcFileLib
+  OcFlexArrayLib
+  OcLegacyThunkLib
+  SortLib
+  UefiBootServicesTableLib
+  UefiDriverEntryPoint
+  UefiLib
+
+[Protocols]
+  gOcBootEntryProtocolGuid            ## PRODUCES
+  gEfiLegacy8259ProtocolGuid          ## SOMETIMES_CONSUMES
+ 
+[Sources]
+  LegacyBootInternal.h
+  LegacyBootSupport.c
+  OpenLegacyBoot.c
diff --git a/Platform/ResetNvramEntry/ResetNvramEntry.c b/Platform/ResetNvramEntry/ResetNvramEntry.c
index 025f53f4325..dae08cf6f1d 100644
--- a/Platform/ResetNvramEntry/ResetNvramEntry.c
+++ b/Platform/ResetNvramEntry/ResetNvramEntry.c
@@ -39,7 +39,8 @@ WaitForChime (
 STATIC
 EFI_STATUS
 SystemActionResetNvram (
-  IN OUT          OC_PICKER_CONTEXT  *PickerContext
+  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
+  IN              VOID               *ActionContext
   )
 {
   UINT8  ResetNVRam = 1;
diff --git a/Platform/ToggleSipEntry/ToggleSipEntry.c b/Platform/ToggleSipEntry/ToggleSipEntry.c
index 96255582045..b4092d562de 100644
--- a/Platform/ToggleSipEntry/ToggleSipEntry.c
+++ b/Platform/ToggleSipEntry/ToggleSipEntry.c
@@ -32,7 +32,8 @@ STATIC BOOLEAN  mShowCsr;
 STATIC
 EFI_STATUS
 SystemActionSetSip (
-  IN OUT          OC_PICKER_CONTEXT  *Context
+  IN OUT          OC_PICKER_CONTEXT  *Context,
+  IN              VOID               *ActionContext
   )
 {
   EFI_STATUS  Status;
diff --git a/build_oc.tool b/build_oc.tool
index 22a7efa0bd0..94d54adb820 100755
--- a/build_oc.tool
+++ b/build_oc.tool
@@ -198,6 +198,7 @@ package() {
       "NvmExpressDxe.efi"
       "OpenCanopy.efi"
       "OpenHfsPlus.efi"
+      "OpenLegacyBoot.efi"
       "OpenLinuxBoot.efi"
       "OpenNtfsDxe.efi"
       "OpenPartitionDxe.efi"

From 3a31eca836b8cba107a01f2b5fde6728212f47ea Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 12 Aug 2023 14:39:39 -0500
Subject: [PATCH 26/55] OpenLegacyBoot: Cleanup state variables

---
 Library/OcLegacyThunkLib/OcLegacyThunkLib.inf |  1 +
 Platform/OpenLegacyBoot/LegacyBootInternal.h  | 27 ++++++-
 Platform/OpenLegacyBoot/LegacyBootSupport.c   | 18 -----
 Platform/OpenLegacyBoot/OpenLegacyBoot.c      | 72 +++++++++----------
 4 files changed, 61 insertions(+), 57 deletions(-)

diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
index 432491c9219..ff863551a03 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
@@ -41,6 +41,7 @@
 
 [Protocols]
   gEfiLegacy8259ProtocolGuid
+  gEfiTimerArchProtocolGuid
 
 [LibraryClasses]
   BaseMemoryLib
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index 4bb6d1dceb2..68b2e76ff98 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -6,8 +6,26 @@
 #ifndef LEGACY_BOOT_INTERNAL_H
 #define LEGACY_BOOT_INTERNAL_H
 
-extern EFI_HANDLE  gImageHandle;
-extern BOOLEAN     gIsAppleInterfaceSupported;
+#include <Uefi.h>
+
+#include <IndustryStandard/Mbr.h>
+
+#include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/OcBootManagementLib.h>
+#include <Library/OcDebugLogLib.h>
+#include <Library/OcDevicePathLib.h>
+#include <Library/OcFileLib.h>
+#include <Library/OcLegacyThunkLib.h>
+#include <Library/OcMiscLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+
+#include <Protocol/DevicePath.h>
+#include <Protocol/Legacy8259.h>
 
 /**
   Legacy operating system type.
@@ -19,6 +37,11 @@ typedef enum OC_LEGACY_OS_TYPE_ {
   OcLegacyOsTypeIsoLinux
 } OC_LEGACY_OS_TYPE;
 
+typedef struct {
+  EFI_HANDLE                  FsHandle;
+  EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
+} OPEN_LEGACY_BOOT_CONTEXT;
+
 EFI_STATUS
 InternalIsLegacyInterfaceSupported (
   OUT BOOLEAN  *IsAppleInterfaceSupported
diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index 1de67a5edc2..5830c8ce8d5 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -5,24 +5,6 @@
 
 #include "LegacyBootInternal.h"
 
-#include <IndustryStandard/Mbr.h>
-
-#include <Library/BaseLib.h>
-#include <Library/BaseMemoryLib.h>
-#include <Library/DevicePathLib.h>
-#include <Library/MemoryAllocationLib.h>
-#include <Library/OcBootManagementLib.h>
-#include <Library/OcDebugLogLib.h>
-#include <Library/OcDevicePathLib.h>
-#include <Library/OcFileLib.h>
-#include <Library/OcLegacyThunkLib.h>
-#include <Library/OcMiscLib.h>
-#include <Library/UefiBootServicesTableLib.h>
-#include <Library/UefiLib.h>
-#include <Library/UefiRuntimeServicesTableLib.h>
-
-#include <Protocol/DevicePath.h>
-#include <Protocol/Legacy8259.h>
 
 THUNK_CONTEXT  mThunkContext;
 
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index e0fc59daa51..e8d2ac7ed11 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -7,22 +7,10 @@
 
 #include "LegacyBootInternal.h"
 
-#include <Uefi.h>
-#include <Guid/Gpt.h>
-#include <Library/BaseLib.h>
-#include <Library/DevicePathLib.h>
-#include <Library/MemoryAllocationLib.h>
-#include <Library/OcBootManagementLib.h>
-#include <Library/OcDebugLogLib.h>
-#include <Library/OcFileLib.h>
-#include <Library/OcFlexArrayLib.h>
-#include <Library/OcStringLib.h>
-#include <Library/UefiBootServicesTableLib.h>
-
 #include <Protocol/OcBootEntry.h>
 
-EFI_HANDLE  gImageHandle;
-BOOLEAN     gIsAppleInterfaceSupported;
+STATIC EFI_HANDLE  mImageHandle;
+STATIC BOOLEAN     mIsAppleInterfaceSupported;
 
 VOID
 InternalFreePickerEntry (
@@ -63,23 +51,28 @@ InternalFreePickerEntry (
 STATIC
 EFI_STATUS
 SystemActionDoLegacyBoot (
-  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
-  IN              VOID               *ActionContext
+  IN OUT  OC_PICKER_CONTEXT  *PickerContext,
+  IN      VOID               *ActionContext
   )
 {
   EFI_STATUS                 Status;
   EFI_HANDLE                 LoadedImageHandle;
   EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
-  EFI_DEVICE_PATH_PROTOCOL   *DevicePath;
-
-  DevicePath = (EFI_DEVICE_PATH_PROTOCOL *)ActionContext;
+  OPEN_LEGACY_BOOT_CONTEXT   *LegacyContext;
 
-  if (gIsAppleInterfaceSupported) {
-    DebugPrintDevicePath (DEBUG_INFO, "LEG: Device path", DevicePath);
+  LegacyContext = (OPEN_LEGACY_BOOT_CONTEXT *)ActionContext;
 
+  //
+  // Load and start legacy OS.
+  //
+  // On Macs, use the Apple legacy interface.
+  // On other systems, use the Legacy8259 protocol.
+  //
+  DebugPrintDevicePath (DEBUG_INFO, "LEG: Legacy device path", LegacyContext->DevicePath);
+  if (mIsAppleInterfaceSupported) {
     Status = InternalLoadAppleLegacyInterface (
-               gImageHandle,
-               DevicePath,
+               mImageHandle,
+               LegacyContext->DevicePath,
                &LoadedImageHandle
                );
     if (EFI_ERROR (Status)) {
@@ -190,17 +183,22 @@ OcGetLegacyBootEntries (
     return EFI_NOT_FOUND;
   }
 
-  PickerEntry                      = AllocateZeroPool (sizeof (*PickerEntry));
-  PickerEntry->Id                  = "legacy_boot";
-  PickerEntry->Name                = "Windows (legacy)";
-  PickerEntry->Path                = NULL;
-  PickerEntry->Arguments           = NULL;
-  PickerEntry->Flavour             = OC_FLAVOUR_WINDOWS;
-  PickerEntry->Tool                = FALSE;
-  PickerEntry->TextMode            = TRUE;
-  PickerEntry->RealPath            = FALSE;
-  PickerEntry->SystemAction        = SystemActionDoLegacyBoot;
-  PickerEntry->SystemActionContext = DevicePathFromHandle (Device);
+  PickerEntry               = AllocateZeroPool (sizeof (*PickerEntry));
+  PickerEntry->Id           = "legacy_boot";
+  PickerEntry->Name         = "Windows (legacy)";
+  PickerEntry->Path         = NULL;
+  PickerEntry->Arguments    = NULL;
+  PickerEntry->Flavour      = OC_FLAVOUR_WINDOWS;
+  PickerEntry->Tool         = FALSE;
+  PickerEntry->TextMode     = TRUE;
+  PickerEntry->RealPath     = FALSE;
+  PickerEntry->SystemAction = SystemActionDoLegacyBoot;
+
+  OPEN_LEGACY_BOOT_CONTEXT  *contex = (OPEN_LEGACY_BOOT_CONTEXT *)AllocateZeroPool (sizeof (OPEN_LEGACY_BOOT_CONTEXT));
+
+  contex->DevicePath               = DevicePathFromHandle (Device);
+  contex->FsHandle                 = Device;
+  PickerEntry->SystemActionContext = contex;
 
   *Entries    = PickerEntry;
   *NumEntries = 1;
@@ -251,15 +249,15 @@ UefiMain (
 {
   EFI_STATUS  Status;
 
-  gImageHandle = ImageHandle;
+  mImageHandle = ImageHandle;
 
-  Status = InternalIsLegacyInterfaceSupported (&gIsAppleInterfaceSupported);
+  Status = InternalIsLegacyInterfaceSupported (&mIsAppleInterfaceSupported);
   if (EFI_ERROR (Status)) {
     DEBUG ((DEBUG_WARN, "LEG: Legacy boot interface is supported on this system\n"));
     return Status;
   }
 
-  DEBUG ((DEBUG_INFO, "LEG: Apple legacy interface: %d\n", gIsAppleInterfaceSupported));
+  DEBUG ((DEBUG_INFO, "LEG: Apple legacy interface: %d\n", mIsAppleInterfaceSupported));
 
   Status = gBS->InstallMultipleProtocolInterfaces (
                   &ImageHandle,

From 61eeb93171795be1b242e54b93285f87534e2914 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 12 Aug 2023 18:52:22 -0500
Subject: [PATCH 27/55] OpenLegacyBoot: Add initial support for PC legacy boot
 interface

---
 Platform/OpenLegacyBoot/BiosDisk.c           | 205 +++++++++++++++++++
 Platform/OpenLegacyBoot/LegacyBootInternal.h |  12 +-
 Platform/OpenLegacyBoot/LegacyBootSupport.c  |  84 ++++++--
 Platform/OpenLegacyBoot/OpenLegacyBoot.c     |   2 +
 Platform/OpenLegacyBoot/OpenLegacyBoot.inf   |   1 +
 5 files changed, 290 insertions(+), 14 deletions(-)
 create mode 100644 Platform/OpenLegacyBoot/BiosDisk.c

diff --git a/Platform/OpenLegacyBoot/BiosDisk.c b/Platform/OpenLegacyBoot/BiosDisk.c
new file mode 100644
index 00000000000..cbe7097ff62
--- /dev/null
+++ b/Platform/OpenLegacyBoot/BiosDisk.c
@@ -0,0 +1,205 @@
+/** @file
+  Copyright (C) 2023, Goldfish64. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-3-Clause
+**/
+
+#include "LegacyBootInternal.h"
+
+//
+// Int 13 BIOS Errors
+//
+#define BIOS_PASS                   0x00
+#define BIOS_WRITE_PROTECTED        0x03
+#define BIOS_SECTOR_NOT_FOUND       0x04
+#define BIOS_RESET_FAILED           0x05
+#define BIOS_DISK_CHANGED           0x06
+#define BIOS_DRIVE_DOES_NOT_EXIST   0x07
+#define BIOS_DMA_ERROR              0x08
+#define BIOS_DATA_BOUNDRY_ERROR     0x09
+#define BIOS_BAD_SECTOR             0x0a
+#define BIOS_BAD_TRACK              0x0b
+#define BIOS_MEADIA_TYPE_NOT_FOUND  0x0c
+#define BIOS_INVALED_FORMAT         0x0d
+#define BIOS_ECC_ERROR              0x10
+#define BIOS_ECC_CORRECTED_ERROR    0x11
+#define BIOS_HARD_DRIVE_FAILURE     0x20
+#define BIOS_SEEK_FAILED            0x40
+#define BIOS_DRIVE_TIMEOUT          0x80
+#define BIOS_DRIVE_NOT_READY        0xaa
+#define BIOS_UNDEFINED_ERROR        0xbb
+#define BIOS_WRITE_FAULT            0xcc
+#define BIOS_SENSE_FAILED           0xff
+
+typedef struct {
+  UINT8     PacketSizeInBytes; // 0x10
+  UINT8     Zero;
+  UINT8     NumberOfBlocks;   // Max 0x7f
+  UINT8     Zero2;
+  UINT32    SegOffset;
+  UINT64    Lba;
+} DEVICE_ADDRESS_PACKET;
+
+STATIC
+EFI_STATUS
+BiosDiskReset (
+  IN  THUNK_CONTEXT             *ThunkContext,
+  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN  UINT8                     DriveNumber
+  )
+{
+  IA32_REGISTER_SET  Regs;
+  UINTN              CarryFlag;
+
+  ZeroMem (&Regs, sizeof (IA32_REGISTER_SET));
+
+  Regs.H.AH = 0x00;
+  Regs.H.DL = DriveNumber;
+  CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
+
+  if (CarryFlag != 0) {
+    DEBUG ((DEBUG_WARN, "LEG: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AL));
+    if (Regs.H.AL == BIOS_RESET_FAILED) {
+      Regs.H.AH = 0x00;
+      Regs.H.DL = DriveNumber;
+      CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
+      if (CarryFlag != 0) {
+        DEBUG ((DEBUG_WARN, "LEG: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AH));
+        return EFI_DEVICE_ERROR;
+      }
+    }
+  }
+
+  return EFI_SUCCESS;
+}
+
+STATIC
+EFI_STATUS
+BiosDiskExtensionsSupported (
+  IN  THUNK_CONTEXT             *ThunkContext,
+  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN  UINT8                     DriveNumber
+  )
+{
+  INTN               CarryFlag;
+  IA32_REGISTER_SET  Regs;
+
+  ZeroMem (&Regs, sizeof (IA32_REGISTER_SET));
+
+  Regs.H.AH = 0x41;
+  Regs.X.BX = 0x55aa;
+  Regs.H.DL = DriveNumber;
+  CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
+
+  if ((CarryFlag != 0) || (Regs.X.BX != 0xaa55)) {
+    return EFI_UNSUPPORTED;
+  }
+
+  return EFI_SUCCESS;
+}
+
+STATIC
+EFI_STATUS
+BiosDiskReadExtSectors (
+  IN      THUNK_CONTEXT             *ThunkContext,
+  IN      EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN      DEVICE_ADDRESS_PACKET     *DeviceAddressPacket,
+  IN      UINT8                     DriveNumber,
+  IN      UINT64                    Lba,
+  IN      UINT8                     NumSectors,
+  IN OUT  UINT8                     *Buffer
+  )
+{
+  INTN               CarryFlag;
+  IA32_REGISTER_SET  Regs;
+
+  ZeroMem (&Regs, sizeof (IA32_REGISTER_SET));
+
+  DeviceAddressPacket->PacketSizeInBytes = sizeof (*DeviceAddressPacket);
+  DeviceAddressPacket->Zero              = 0;
+  DeviceAddressPacket->NumberOfBlocks    = NumSectors;
+  DeviceAddressPacket->Zero2             = 0;
+  DeviceAddressPacket->SegOffset         = (UINT32)LShiftU64 (RShiftU64 ((UINTN)Buffer, 4), 16);
+  DeviceAddressPacket->Lba               = Lba;
+
+  Regs.H.AH = 0x42;
+  Regs.H.DL = DriveNumber;
+  Regs.X.SI = EFI_OFFSET (DeviceAddressPacket);
+  Regs.E.DS = EFI_SEGMENT (DeviceAddressPacket);
+  CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
+
+  DEBUG ((DEBUG_INFO, "carry %u\n", CarryFlag));
+
+  return EFI_SUCCESS;
+}
+
+EFI_STATUS
+InternalGetBiosDiskNumber (
+  IN      THUNK_CONTEXT             *ThunkContext,
+  IN      EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  OUT  UINT8                        *DriveNumber
+  )
+{
+  EFI_STATUS             Status;
+  UINT8                  DriveAddr;
+  EFI_PHYSICAL_ADDRESS   DeviceAddressPacketAddress;
+  DEVICE_ADDRESS_PACKET  *DeviceAddressPacket;
+  UINT8                  *Buffer;
+
+  //
+  // Allocate low memory buffer for disk reads.
+  //
+  DeviceAddressPacketAddress = (SIZE_1MB - 1);
+  Status                     = gBS->AllocatePages (
+                                      AllocateMaxAddress,
+                                      EfiBootServicesData,
+                                      EFI_SIZE_TO_PAGES (sizeof (*DeviceAddressPacket) + (MBR_SIZE * 4)) + 1,
+                                      &DeviceAddressPacketAddress
+                                      );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_WARN, "LEG: Failure allocating low memory packet for BIOS disk read - %r\n", Status));
+    return Status;
+  }
+
+  DeviceAddressPacket = (DEVICE_ADDRESS_PACKET *)DeviceAddressPacketAddress;
+  Buffer              = (UINT8 *)DeviceAddressPacketAddress + 0x200;
+
+  //
+  // Locate disk with matching checksum of first few sectors.
+  //
+  for (DriveAddr = 0x80; DriveAddr < 0x88; DriveAddr++) {
+    DEBUG ((DEBUG_INFO, "drive %X\n", DriveAddr));
+
+    //
+    // Reset disk and verify INT13H extensions are supported.
+    //
+    Status = BiosDiskReset (ThunkContext, Legacy8259, DriveAddr);
+    if (EFI_ERROR (Status)) {
+      continue;
+    }
+
+    Status = BiosDiskExtensionsSupported (ThunkContext, Legacy8259, DriveAddr);
+    if (EFI_ERROR (Status)) {
+      continue;
+    }
+
+    //
+    // Read sectors from disk.
+    //
+    Status = BiosDiskReadExtSectors (
+               ThunkContext,
+               Legacy8259,
+               DeviceAddressPacket,
+               DriveAddr,
+               0,
+               4,
+               Buffer
+               );
+    if (EFI_ERROR (Status)) {
+      continue;
+    }
+
+    DebugPrintHexDump (DEBUG_INFO, "raw bios bytes", Buffer, 512);
+  }
+
+  return EFI_SUCCESS;
+}
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index 68b2e76ff98..c6b4699575c 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -42,6 +42,13 @@ typedef struct {
   EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
 } OPEN_LEGACY_BOOT_CONTEXT;
 
+EFI_STATUS
+InternalGetBiosDiskNumber (
+  IN      THUNK_CONTEXT             *ThunkContext,
+  IN      EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  OUT  UINT8                        *DriveNumber
+  );
+
 EFI_STATUS
 InternalIsLegacyInterfaceSupported (
   OUT BOOLEAN  *IsAppleInterfaceSupported
@@ -60,8 +67,9 @@ InternalGetPartitionLegacyOsType (
   );
 
 EFI_STATUS
-InternalLoadLegacyMbr (
-  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
+InternalLoadLegacyPbr (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *PartitionPath,
+  IN  EFI_HANDLE                PartitionHandle
   );
 
 #endif // LEGACY_BOOT_INTERNAL_H
diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index 5830c8ce8d5..9196ba94379 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -356,20 +356,25 @@ InternalGetPartitionLegacyOsType (
 }
 
 EFI_STATUS
-InternalLoadLegacyMbr (
-  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
+InternalLoadLegacyPbr (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *PartitionPath,
+  IN  EFI_HANDLE                PartitionHandle
   )
 {
   EFI_STATUS          Status;
   EFI_HANDLE          DiskHandle;
   MASTER_BOOT_RECORD  *Mbr;
-  IA32_REGISTER_SET   Regs;
-  UINT8               *MbrPtr = (UINT8 *)0x7C00;
+  MASTER_BOOT_RECORD  *Pbr;
+  UINTN               PbrSize;
+  OC_DISK_CONTEXT     DiskContext;
 
+  IA32_REGISTER_SET         Regs;
+  MASTER_BOOT_RECORD        *MbrPtr = (MASTER_BOOT_RECORD *)0x0600;
+  MASTER_BOOT_RECORD        *PbrPtr = (MASTER_BOOT_RECORD *)0x7C00;
   EFI_LEGACY_8259_PROTOCOL  *Legacy8259;
 
   //
-  // Locate required protocols.
+  // Locate Legacy8259 protocol.
   //
   Status = gBS->LocateProtocol (
                   &gEfiLegacy8259ProtocolGuid,
@@ -377,20 +382,55 @@ InternalLoadLegacyMbr (
                   (VOID **)&Legacy8259
                   );
   if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_INFO, "OCB: Could not locate Legacy8259 protocol\n"));
+    DEBUG ((DEBUG_INFO, "LEG: Could not locate Legacy8259 protocol\n"));
     return Status;
   }
 
-  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading MBR for disk", HdDevicePath);
+  //
+  // Retrieve the PBR from partition.
+  //
+  Status = OcDiskInitializeContext (
+             &DiskContext,
+             PartitionHandle,
+             TRUE
+             );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  PbrSize = ALIGN_VALUE (sizeof (*Pbr), DiskContext.BlockSize);
+  Pbr     = (MASTER_BOOT_RECORD *)AllocatePool (PbrSize);
+  if (Pbr == NULL) {
+    DEBUG ((DEBUG_INFO, "LEG: Buffer allocation error\n"));
+    return EFI_OUT_OF_RESOURCES;
+  }
 
-  DiskHandle = OcPartitionGetDiskHandle (HdDevicePath);
+  Status = OcDiskRead (
+             &DiskContext,
+             0,
+             PbrSize,
+             Pbr
+             );
+  if (EFI_ERROR (Status)) {
+    FreePool (Pbr);
+    return Status;
+  }
+
+  DebugPrintHexDump (DEBUG_INFO, "LEG: PbrHEX", (UINT8 *)Pbr, sizeof (*Pbr));
+
+  //
+  // Retrieve MBR from disk.
+  //
+  DiskHandle = OcPartitionGetDiskHandle (PartitionPath);
   if (DiskHandle == NULL) {
+    FreePool (Pbr);
     return EFI_INVALID_PARAMETER;
   }
 
   Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
   if (Mbr == NULL) {
-    DEBUG ((DEBUG_INFO, "OCB: Disk does not contain a valid MBR partition table\n"));
+    DEBUG ((DEBUG_INFO, "LEG: Disk does not contain a valid MBR partition table\n"));
+    FreePool (Pbr);
     return EFI_INVALID_PARAMETER;
   }
 
@@ -399,22 +439,42 @@ InternalLoadLegacyMbr (
   //
   Status = OcLegacyThunkInitializeBiosIntCaller (&mThunkContext);
   if (EFI_ERROR (Status)) {
+    FreePool (Pbr);
+    FreePool (Mbr);
     return Status;
   }
 
   Status = OcLegacyThunkInitializeInterruptRedirection (Legacy8259);
   if (EFI_ERROR (Status)) {
+    FreePool (Pbr);
+    FreePool (Mbr);
     return Status;
   }
 
-  DEBUG ((DEBUG_INFO, "OCB: Preparing to boot legacy system\n"));
+  //
+  // Determine BIOS disk number.
+  //
+  InternalGetBiosDiskNumber (&mThunkContext, Legacy8259, NULL);
+
+  //
+  // Copy MBR and PBR to low memory locations for booting.
+  //
+  CopyMem (PbrPtr, Pbr, sizeof (*Pbr));
+  CopyMem (MbrPtr, Mbr, sizeof (*Mbr));
+
+  DebugPrintHexDump (DEBUG_INFO, "LEG: PbrPtr", (UINT8 *)PbrPtr, sizeof (*PbrPtr));
 
   OcLegacyThunkDisconnectEfiGraphics ();
 
-  CopyMem (MbrPtr, Mbr, sizeof (*Mbr));
 
+  //
+  // Thunk to real mode and invoke legacy boot sector.
+  // If successful, this function will not return.
+  //
   ZeroMem (&Regs, sizeof (Regs));
-  Regs.X.DX = 0x82;
+
+  Regs.H.DL = 0x80;
+  Regs.X.SI = (UINT16)(UINTN)&MbrPtr->Partition[2];
   OcLegacyThunkFarCall86 (
     &mThunkContext,
     Legacy8259,
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index e8d2ac7ed11..c622c0a09c5 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -108,6 +108,8 @@ SystemActionDoLegacyBoot (
       DEBUG ((DEBUG_WARN, "LEG: Failure while starting Apple legacy interface - %r\n", Status));
       return Status;
     }
+  } else {
+    InternalLoadLegacyPbr (LegacyContext->DevicePath, LegacyContext->FsHandle);
   }
 
   return EFI_SUCCESS;
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.inf b/Platform/OpenLegacyBoot/OpenLegacyBoot.inf
index 80da3de5fdd..c553c39c255 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.inf
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.inf
@@ -39,6 +39,7 @@
   gEfiLegacy8259ProtocolGuid          ## SOMETIMES_CONSUMES
  
 [Sources]
+  BiosDisk.c
   LegacyBootInternal.h
   LegacyBootSupport.c
   OpenLegacyBoot.c

From 5b8063f1d13238d810c7a4c68283a428ae6788fb Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 13 Aug 2023 20:44:15 -0500
Subject: [PATCH 28/55] OpenLegacyBoot: Switch to separate action type for
 legacy entries

---
 .../Acidanthera/Library/OcBootManagementLib.h | 100 +++++++-------
 Include/Acidanthera/Library/OcFileLib.h       |  14 +-
 Include/Acidanthera/Protocol/OcBootEntry.h    |   2 +-
 Library/OcBootManagementLib/BootEntryInfo.c   |   2 +-
 .../OcBootManagementLib/BootEntryManagement.c | 122 ++++++++++++++----
 .../OcBootManagementLib/DefaultEntryChoice.c  |   1 +
 Library/OcFileLib/DiskMisc.c                  | 114 +++++++++++++---
 Platform/OpenLegacyBoot/LegacyBootInternal.h  |   5 -
 Platform/OpenLegacyBoot/LegacyBootSupport.c   |   2 -
 Platform/OpenLegacyBoot/OpenLegacyBoot.c      |  46 +++----
 Platform/ResetNvramEntry/ResetNvramEntry.c    |   3 +-
 Platform/ToggleSipEntry/ToggleSipEntry.c      |   3 +-
 12 files changed, 289 insertions(+), 125 deletions(-)

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index 7ce19037501..0f7ea2518fe 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -152,6 +152,7 @@ typedef UINT32 OC_BOOT_ENTRY_TYPE;
 #define OC_BOOT_EXTERNAL_OS         BIT6
 #define OC_BOOT_EXTERNAL_TOOL       BIT7
 #define OC_BOOT_SYSTEM              BIT8
+#define OC_BOOT_EXTERNAL_SYSTEM     BIT9
 
 /**
   Picker mode.
@@ -190,8 +191,17 @@ typedef enum OC_PICKER_MODE_ {
 typedef
 EFI_STATUS
 (*OC_BOOT_SYSTEM_ACTION) (
-  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
-  IN              VOID               *ActionContext
+  IN OUT          OC_PICKER_CONTEXT  *PickerContext
+  );
+
+/**
+  Action to perform as part of executing an external boot system boot entry.
+**/
+typedef
+EFI_STATUS
+(*OC_BOOT_EXTERNAL_SYSTEM_ACTION) (
+  IN OUT          OC_PICKER_CONTEXT         *PickerContext,
+  IN              EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   );
 
 /**
@@ -202,107 +212,107 @@ typedef struct OC_BOOT_ENTRY_ {
   //
   // Link in entry list in OC_BOOT_FILESYSTEM.
   //
-  LIST_ENTRY                  Link;
+  LIST_ENTRY                        Link;
   //
   // Device path to booter or its directory.
   // Can be NULL, for example, for custom or system entries.
   //
-  EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
+  EFI_DEVICE_PATH_PROTOCOL          *DevicePath;
   //
   // Action to perform on execution. Only valid for system entries.
   //
-  OC_BOOT_SYSTEM_ACTION       SystemAction;
+  OC_BOOT_SYSTEM_ACTION             SystemAction;
   //
-  // Context for action to perform on execution for system entries.
+  // Action to perform on execution. Only valid for external boot system entries.
   //
-  VOID                        *SystemActionContext;
+  OC_BOOT_EXTERNAL_SYSTEM_ACTION    ExternalSystemAction;
   //
   // Id under which to save entry as default.
   //
-  CHAR16                      *Id;
+  CHAR16                            *Id;
   //
   // Obtained human visible name.
   //
-  CHAR16                      *Name;
+  CHAR16                            *Name;
   //
   // Obtained boot path directory.
   // For custom entries this contains tool path.
   //
-  CHAR16                      *PathName;
+  CHAR16                            *PathName;
   //
   // Content flavour.
   //
-  CHAR8                       *Flavour;
+  CHAR8                             *Flavour;
   //
   // Heuristical value signaling inferred type of booted os.
   // WARNING: Non-definitive, do not rely on for any security purposes.
   //
-  OC_BOOT_ENTRY_TYPE          Type;
+  OC_BOOT_ENTRY_TYPE                Type;
   //
   // Entry index number, assigned by picker.
   //
-  UINT32                      EntryIndex;
+  UINT32                            EntryIndex;
   //
   // Set when this entry is an externally available entry (e.g. USB).
   //
-  BOOLEAN                     IsExternal;
+  BOOLEAN                           IsExternal;
   //
   // Should try booting from first dmg found in DevicePath.
   //
-  BOOLEAN                     IsFolder;
+  BOOLEAN                           IsFolder;
   //
   // Set when this entry refers to a generic booter (e.g. BOOTx64.EFI).
   //
-  BOOLEAN                     IsGeneric;
+  BOOLEAN                           IsGeneric;
   //
   // Set when this entry refers to a custom boot entry.
   //
-  BOOLEAN                     IsCustom;
+  BOOLEAN                           IsCustom;
   //
   // Set when entry was created by OC_BOOT_ENTRY_PROTOCOL.
   //
-  BOOLEAN                     IsBootEntryProtocol;
+  BOOLEAN                           IsBootEntryProtocol;
   //
   // Set when entry is identified as macOS installer.
   //
-  BOOLEAN                     IsAppleInstaller;
+  BOOLEAN                           IsAppleInstaller;
   //
   // Should make this option default boot option.
   //
-  BOOLEAN                     SetDefault;
+  BOOLEAN                           SetDefault;
   //
   // Should launch this entry in text mode.
   //
-  BOOLEAN                     LaunchInText;
+  BOOLEAN                           LaunchInText;
   //
   // Should expose real device path when dealing with custom entries.
   //
-  BOOLEAN                     ExposeDevicePath;
+  BOOLEAN                           ExposeDevicePath;
   //
   // Should disable OpenRuntime NVRAM protection around invocation of tool.
   //
-  BOOLEAN                     FullNvramAccess;
+  BOOLEAN                           FullNvramAccess;
   //
   // Partition UUID of entry device.
   // Set for non-system action boot entry protocol boot entries only.
   //
-  EFI_GUID                    UniquePartitionGUID;
+  EFI_GUID                          UniquePartitionGUID;
   //
   // Load option data (usually "boot args") size.
   //
-  UINT32                      LoadOptionsSize;
+  UINT32                            LoadOptionsSize;
   //
   // Load option data (usually "boot args").
   //
-  VOID                        *LoadOptions;
+  VOID                              *LoadOptions;
   //
   // Audio base path for system action. Boot Entry Protocol only.
   //
-  CHAR8                       *AudioBasePath;
+  CHAR8                             *AudioBasePath;
   //
   // Audio base type for system action. Boot Entry Protocol only.
   //
-  CHAR8                       *AudioBaseType;
+  CHAR8                             *AudioBaseType;
 } OC_BOOT_ENTRY;
 
 /**
@@ -562,60 +572,60 @@ typedef struct {
   // Multiple entries may share an id - allows e.g. newest version
   // of Linux install to automatically become selected default.
   //
-  CONST CHAR8              *Id;
+  CONST CHAR8                       *Id;
   //
   // Entry name.
   //
-  CONST CHAR8              *Name;
+  CONST CHAR8                       *Name;
   //
   // Absolute device path to file for user custom entries,
   // file path relative to device root for boot entry protocol.
   //
-  CONST CHAR8              *Path;
+  CONST CHAR8                       *Path;
   //
   // Entry boot arguments.
   //
-  CONST CHAR8              *Arguments;
+  CONST CHAR8                       *Arguments;
   //
   // Content flavour.
   //
-  CONST CHAR8              *Flavour;
+  CONST CHAR8                       *Flavour;
   //
   // Whether this entry is auxiliary.
   //
-  BOOLEAN                  Auxiliary;
+  BOOLEAN                           Auxiliary;
   //
   // Whether this entry is a tool.
   //
-  BOOLEAN                  Tool;
+  BOOLEAN                           Tool;
   //
   // Whether it should be started in text mode.
   //
-  BOOLEAN                  TextMode;
+  BOOLEAN                           TextMode;
   //
   // Whether we should pass the actual device path (if possible).
   //
-  BOOLEAN                  RealPath;
+  BOOLEAN                           RealPath;
   //
   // Should disable OpenRuntime NVRAM protection around invocation of tool.
   //
-  BOOLEAN                  FullNvramAccess;
+  BOOLEAN                           FullNvramAccess;
   //
   // System action. Boot Entry Protocol only. Optional.
   //
-  OC_BOOT_SYSTEM_ACTION    SystemAction;
-  //
-  // System action context. Boot Entry Protocol only. Optional.
-  //
-  VOID                     *SystemActionContext;
+  OC_BOOT_SYSTEM_ACTION             SystemAction;
   //
   // Audio base path for system action. Boot Entry Protocol only. Optional.
   //
-  CHAR8                    *AudioBasePath;
+  CHAR8                             *AudioBasePath;
   //
   // Audio base type for system action. Boot Entry Protocol only. Optional.
   //
-  CHAR8                    *AudioBaseType;
+  CHAR8                             *AudioBaseType;
+  //
+  // External boot system action. Boot Entry Protocol only. Optional.
+  //
+  OC_BOOT_EXTERNAL_SYSTEM_ACTION    ExternalSystemAction;
 } OC_PICKER_ENTRY;
 
 /**
diff --git a/Include/Acidanthera/Library/OcFileLib.h b/Include/Acidanthera/Library/OcFileLib.h
index c7c3c178467..a86fbd5d9b8 100644
--- a/Include/Acidanthera/Library/OcFileLib.h
+++ b/Include/Acidanthera/Library/OcFileLib.h
@@ -508,6 +508,17 @@ OcPartitionGetDiskHandle (
   IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   );
 
+/**
+  Retrieve the partition's device handle from a partition's Device Path.
+
+  @param[in] HdDevicePath  The Device Path of the partition.
+
+**/
+EFI_HANDLE
+OcPartitionGetPartitionHandle (
+  IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
+  );
+
 /**
   Check if disk is a CD-ROM device.
 
@@ -633,7 +644,8 @@ OcGetDiskMbrTable (
 EFI_DEVICE_PATH_PROTOCOL *
 OcDiskFindActiveMbrPartitionPath (
   IN  EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
-  OUT UINTN                     *PartitionDevicePathSize
+  OUT UINTN                     *PartitionDevicePathSize,
+  OUT EFI_HANDLE                *PartitionDeviceHandle
   );
 
 /**
diff --git a/Include/Acidanthera/Protocol/OcBootEntry.h b/Include/Acidanthera/Protocol/OcBootEntry.h
index 85c5bba6835..9ac8326c89a 100644
--- a/Include/Acidanthera/Protocol/OcBootEntry.h
+++ b/Include/Acidanthera/Protocol/OcBootEntry.h
@@ -28,7 +28,7 @@
 
   WARNING: This protocol is currently undergoing active design.
 **/
-#define OC_BOOT_ENTRY_PROTOCOL_REVISION  4
+#define OC_BOOT_ENTRY_PROTOCOL_REVISION  5
 
 /**
   Forward declaration of OC_BOOT_ENTRY_PROTOCOL structure.
diff --git a/Library/OcBootManagementLib/BootEntryInfo.c b/Library/OcBootManagementLib/BootEntryInfo.c
index b150ea334bb..0f2b937fd55 100644
--- a/Library/OcBootManagementLib/BootEntryInfo.c
+++ b/Library/OcBootManagementLib/BootEntryInfo.c
@@ -597,7 +597,7 @@ OcGetBootEntryFile (
   IN  BOOLEAN        SearchAtRoot
   )
 {
-  if ((BootEntry->Type & (OC_BOOT_EXTERNAL_TOOL | OC_BOOT_SYSTEM)) != 0) {
+  if ((BootEntry->Type & (OC_BOOT_EXTERNAL_TOOL | OC_BOOT_SYSTEM | OC_BOOT_EXTERNAL_SYSTEM)) != 0) {
     return EFI_NOT_FOUND;
   }
 
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index c27932c6292..9fbe2a2ccb6 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -691,7 +691,7 @@ InternalAddBootEntryFromCustomEntry (
     return EFI_OUT_OF_RESOURCES;
   }
 
-  if (!CustomEntry->SystemAction) {
+  if (!CustomEntry->ExternalSystemAction && !CustomEntry->SystemAction) {
     ASSERT (CustomEntry->Path != NULL);
     PathName = AsciiStrCopyToUnicode (CustomEntry->Path, 0);
     if (PathName == NULL) {
@@ -714,17 +714,27 @@ InternalAddBootEntryFromCustomEntry (
     DEBUG_INFO,
     "OCB: Adding custom entry %s (%a|B:%d) -> %a\n",
     BootEntry->Name,
-    CustomEntry->SystemAction != NULL ? "action" : (CustomEntry->Tool ? "tool" : "os"),
+    CustomEntry->ExternalSystemAction != NULL ? "ext-action" : (CustomEntry->SystemAction != NULL ? "action" : (CustomEntry->Tool ? "tool" : "os")),
     IsBootEntryProtocol,
     CustomEntry->Path
     ));
 
-  if (CustomEntry->SystemAction) {
-    BootEntry->Type                = OC_BOOT_SYSTEM;
-    BootEntry->SystemAction        = CustomEntry->SystemAction;
-    BootEntry->SystemActionContext = CustomEntry->SystemActionContext;
-    BootEntry->AudioBasePath       = CustomEntry->AudioBasePath;
-    BootEntry->AudioBaseType       = CustomEntry->AudioBaseType;
+  if (CustomEntry->ExternalSystemAction) {
+    BootEntry->Type                 = OC_BOOT_EXTERNAL_SYSTEM;
+    BootEntry->ExternalSystemAction = CustomEntry->ExternalSystemAction;
+    BootEntry->AudioBasePath        = CustomEntry->AudioBasePath;
+    BootEntry->AudioBaseType        = CustomEntry->AudioBaseType;
+    BootEntry->DevicePath           = DevicePathFromHandle (FileSystem->Handle);
+
+    if (BootEntry->DevicePath == NULL) {
+      FreeBootEntry (BootEntry);
+      return EFI_OUT_OF_RESOURCES;
+    }
+  } else if (CustomEntry->SystemAction) {
+    BootEntry->Type          = OC_BOOT_SYSTEM;
+    BootEntry->SystemAction  = CustomEntry->SystemAction;
+    BootEntry->AudioBasePath = CustomEntry->AudioBasePath;
+    BootEntry->AudioBaseType = CustomEntry->AudioBaseType;
   } else if (CustomEntry->Tool) {
     BootEntry->Type = OC_BOOT_EXTERNAL_TOOL;
     UnicodeUefiSlashes (PathName);
@@ -830,7 +840,7 @@ InternalAddBootEntryFromCustomEntry (
   BootEntry->ExposeDevicePath = CustomEntry->RealPath;
   BootEntry->FullNvramAccess  = CustomEntry->FullNvramAccess;
 
-  if (BootEntry->SystemAction != NULL) {
+  if ((BootEntry->ExternalSystemAction != NULL) || (BootEntry->SystemAction != NULL)) {
     ASSERT (CustomEntry->Arguments == NULL);
   } else {
     ASSERT (CustomEntry->Arguments != NULL);
@@ -848,7 +858,7 @@ InternalAddBootEntryFromCustomEntry (
 
   BootEntry->IsCustom            = TRUE;
   BootEntry->IsBootEntryProtocol = IsBootEntryProtocol;
-  if (IsBootEntryProtocol && (BootEntry->SystemAction == NULL)) {
+  if (IsBootEntryProtocol && (BootEntry->ExternalSystemAction == NULL) && (BootEntry->SystemAction == NULL)) {
     PartitionEntry = OcGetGptPartitionEntry (FileSystem->Handle);
     if (PartitionEntry == NULL) {
       CopyGuid (&BootEntry->UniquePartitionGUID, &gEfiPartTypeUnusedGuid);
@@ -1213,8 +1223,10 @@ AddBootEntryFromBootOption (
   EFI_HANDLE                FileSystemHandle;
   OC_BOOT_FILESYSTEM        *FileSystem;
   UINTN                     DevicePathSize;
+  CHAR16                    *TextDevicePath;
   INTN                      NumPatchedNodes;
   BOOLEAN                   IsAppleLegacy;
+  BOOLEAN                   IsAppleLegacyHandled;
   BOOLEAN                   IsRoot;
   EFI_LOAD_OPTION           *LoadOption;
   UINTN                     LoadOptionSize;
@@ -1306,6 +1318,7 @@ AddBootEntryFromBootOption (
   //
   // Expand BootCamp device path to EFI partition device path.
   //
+  IsAppleLegacyHandled = FALSE;
   if (IsAppleLegacy) {
     //
     // BootCampHD always refers to a full Device Path. Failure to patch
@@ -1317,13 +1330,77 @@ AddBootEntryFromBootOption (
       return EFI_NOT_FOUND;
     }
 
+    //
+    // Attempt to handle detected legacy OS.
+    //
     RemainingDevicePath = DevicePath;
-    DevicePath          = OcDiskFindSystemPartitionPath (
+    DevicePath          = OcDiskFindActiveMbrPartitionPath (
                             DevicePath,
                             &DevicePathSize,
                             &FileSystemHandle
                             );
 
+    //
+    // Disk with MBR or hybrid MBR was detected.
+    //
+    if (DevicePath != NULL) {
+      //
+      // Ensure that we are allowed to boot from this filesystem.
+      //
+      FileSystem = InternalFileSystemForHandle (BootContext, FileSystemHandle, TRUE, NULL);
+      if (FileSystem != NULL) {
+        TextDevicePath = ConvertDevicePathToText (DevicePath, FALSE, FALSE);
+        if (TextDevicePath != NULL) {
+          //
+          // Add entry from externally provided legacy interface.
+          //
+          Status = OcAddEntriesFromBootEntryProtocol (
+                     BootContext,
+                     FileSystem,
+                     EntryProtocolHandles,
+                     EntryProtocolHandleCount,
+                     TextDevicePath,
+                     TRUE,
+                     FALSE
+                     );
+          if (!EFI_ERROR (Status)) {
+            if (EntryProtocolId != NULL) {
+              *EntryProtocolId = TextDevicePath;
+            }
+
+            IsAppleLegacyHandled = TRUE;
+          } else {
+            FreePool (TextDevicePath);
+          }
+        }
+      }
+    }
+
+    if (!IsAppleLegacyHandled) {
+      //
+      // Boot option was set to Apple legacy interface incorrectly by macOS.
+      // This will occur on Macs that normally boot Windows in legacy mode,
+      // but have Windows installed in UEFI mode.
+      //
+      // Locate the ESP from the BootCampHD Device Path instead.
+      //
+      DevicePath = OcDiskFindSystemPartitionPath (
+                     RemainingDevicePath,
+                     &DevicePathSize,
+                     &FileSystemHandle
+                     );
+
+      //
+      // Ensure that we are allowed to boot from this filesystem.
+      //
+      if (DevicePath != NULL) {
+        FileSystem = InternalFileSystemForHandle (BootContext, FileSystemHandle, LazyScan, NULL);
+        if (FileSystem == NULL) {
+          DevicePath = NULL;
+        }
+      }
+    }
+
     FreePool (RemainingDevicePath);
 
     //
@@ -1331,16 +1408,6 @@ AddBootEntryFromBootOption (
     //
     IsRoot = TRUE;
 
-    //
-    // Ensure that we are allowed to boot from this filesystem.
-    //
-    if (DevicePath != NULL) {
-      FileSystem = InternalFileSystemForHandle (BootContext, FileSystemHandle, LazyScan, NULL);
-      if (FileSystem == NULL) {
-        DevicePath = NULL;
-      }
-    }
-
     //
     // The Device Path returned by OcDiskFindSystemPartitionPath() is a pointer
     // to an installed protocol. Duplicate it so we own the memory.
@@ -1566,6 +1633,10 @@ AddBootEntryFromBootOption (
     FreePool (DevicePath);
   }
 
+  if (IsAppleLegacyHandled) {
+    return EFI_SUCCESS;
+  }
+
   //
   // We may have a Boot#### entry pointing to macOS with full DP (up to boot.efi),
   // so IsRoot will be true. However, if this is APFS, we may still have:
@@ -2089,6 +2160,8 @@ OcScanForBootEntries (
                                            )
                                          );
 
+    IsDefaultEntryProtocolPartition = (DefaultEntryId != NULL);
+
     //
     // No entries, or only entry pre-created from boot entry protocol,
     // so process this directory with Apple Bless.
@@ -2441,9 +2514,14 @@ OcLoadBootEntry (
   EFI_HANDLE                 EntryHandle;
   INTERNAL_DMG_LOAD_CONTEXT  DmgLoadContext;
 
+  if ((BootEntry->Type & OC_BOOT_EXTERNAL_SYSTEM) != 0) {
+    ASSERT (BootEntry->ExternalSystemAction != NULL);
+    return BootEntry->ExternalSystemAction (Context, BootEntry->DevicePath);
+  }
+
   if ((BootEntry->Type & OC_BOOT_SYSTEM) != 0) {
     ASSERT (BootEntry->SystemAction != NULL);
-    return BootEntry->SystemAction (Context, BootEntry->SystemActionContext);
+    return BootEntry->SystemAction (Context);
   }
 
   Status = InternalLoadBootEntry (
diff --git a/Library/OcBootManagementLib/DefaultEntryChoice.c b/Library/OcBootManagementLib/DefaultEntryChoice.c
index 5c118fc072f..a51d8472e7a 100644
--- a/Library/OcBootManagementLib/DefaultEntryChoice.c
+++ b/Library/OcBootManagementLib/DefaultEntryChoice.c
@@ -1515,6 +1515,7 @@ InternalLoadBootEntry (
   //
   // System entries are not loaded but called directly.
   //
+  ASSERT ((BootEntry->Type & OC_BOOT_EXTERNAL_SYSTEM) == 0);
   ASSERT ((BootEntry->Type & OC_BOOT_SYSTEM) == 0);
   ASSERT (Context != NULL);
   ASSERT (DmgLoadContext != NULL);
diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index e6f228197bf..cf590d05db3 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -305,6 +305,28 @@ OcPartitionGetDiskHandle (
            );
 }
 
+/**
+  Retrieve the partition's device handle from a partition's Device Path.
+
+  @param[in] HdDevicePath  The Device Path of the partition.
+
+**/
+EFI_HANDLE
+OcPartitionGetPartitionHandle (
+  IN EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
+  )
+{
+  BOOLEAN  Dummy;
+
+  ASSERT (HdDevicePath != NULL);
+
+  return InternalGetDiskHandle (
+           HdDevicePath,
+           FALSE,
+           &Dummy
+           );
+}
+
 BOOLEAN
 OcIsDiskCdRom (
   IN EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath
@@ -777,7 +799,8 @@ OcGetDiskMbrTable (
 EFI_DEVICE_PATH_PROTOCOL *
 OcDiskFindActiveMbrPartitionPath (
   IN  EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
-  OUT UINTN                     *PartitionDevicePathSize
+  OUT UINTN                     *PartitionDevicePathSize,
+  OUT EFI_HANDLE                *PartitionDeviceHandle
   )
 {
   EFI_STATUS  Status;
@@ -785,15 +808,41 @@ OcDiskFindActiveMbrPartitionPath (
   BOOLEAN     HasBlockIo2;
   UINTN       Index;
   INT32       ActivePartition;
+  BOOLEAN     Result;
+  INTN        CmpResult;
 
   UINTN                     NoHandles;
   EFI_HANDLE                *Handles;
-  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
+  EFI_DEVICE_PATH_PROTOCOL  *PartitionDevicePath;
   HARDDRIVE_DEVICE_PATH     *HdNode;
   MASTER_BOOT_RECORD        *Mbr;
 
+  UINTN                     DiskDpSize;
+  UINTN                     DiskDpCmpSize;
+  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath;
+  UINTN                     HdDpSize;
+
   ASSERT (DiskDevicePath != NULL);
   ASSERT (PartitionDevicePathSize != NULL);
+  ASSERT (PartitionDeviceHandle != NULL);
+
+  DebugPrintDevicePath (
+    DEBUG_INFO,
+    "OCPI: Locating MBR disk's active partition",
+    (EFI_DEVICE_PATH_PROTOCOL *)DiskDevicePath
+    );
+
+  Status = gBS->LocateHandleBuffer (
+                  ByProtocol,
+                  &gEfiSimpleFileSystemProtocolGuid,
+                  NULL,
+                  &NoHandles,
+                  &Handles
+                  );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_INFO, "OCPI: Failed to locate FS handles\n"));
+    return NULL;
+  }
 
   //
   // Get MBR partition table from disk.
@@ -835,41 +884,68 @@ OcDiskFindActiveMbrPartitionPath (
     return NULL;
   }
 
-  Status = gBS->LocateHandleBuffer (
-                  ByProtocol,
-                  &gEfiBlockIoProtocolGuid,
-                  NULL,
-                  &NoHandles,
-                  &Handles
-                  );
-  if (EFI_ERROR (Status)) {
+  //
+  // The partition's Device Path must be at least as big as the disk's (prefix)
+  // plus an additional HardDrive node.
+  //
+  DiskDpSize = GetDevicePathSize (DiskDevicePath);
+  Result     = BaseOverflowAddUN (
+                 DiskDpSize,
+                 sizeof (HARDDRIVE_DEVICE_PATH),
+                 &DiskDpCmpSize
+                 );
+  if (Result) {
+    DEBUG ((DEBUG_INFO, "OCPI: HD node would overflow DP\n"));
     FreePool (Mbr);
     return NULL;
   }
 
+  PartitionDevicePath = NULL;
+
   for (Index = 0; Index < NoHandles; Index++) {
-    DevicePath = DevicePathFromHandle (Handles[Index]);
-    if (DevicePath == NULL) {
+    HdDevicePath = DevicePathFromHandle (Handles[Index]);
+    if (HdDevicePath == NULL) {
       continue;
     }
 
-    if (CompareMem (DevicePath, DiskDevicePath, GetDevicePathSize (DiskDevicePath) - END_DEVICE_PATH_LENGTH) == 0) {
+    HdDpSize = GetDevicePathSize (HdDevicePath);
+    if (HdDpSize < DiskDpCmpSize) {
+      continue;
+    }
+
+    //
+    // Verify the partition's Device Path has the disk's prefixed.
+    //
+    CmpResult = CompareMem (
+                  HdDevicePath,
+                  DiskDevicePath,
+                  DiskDpSize - END_DEVICE_PATH_LENGTH
+                  );
+    if (CmpResult != 0) {
+      continue;
+    }
+
+    if (CompareMem (HdDevicePath, DiskDevicePath, GetDevicePathSize (DiskDevicePath) - END_DEVICE_PATH_LENGTH) == 0) {
       HdNode = (HARDDRIVE_DEVICE_PATH *)FindDevicePathNodeWithType (
-                                          DevicePath,
+                                          HdDevicePath,
                                           MEDIA_DEVICE_PATH,
                                           MEDIA_HARDDRIVE_DP
                                           );
       if (HdNode != NULL) {
         if (HdNode->PartitionStart == *((UINT32 *)Mbr->Partition[ActivePartition].StartingLBA)) {
-          DebugPrintDevicePath (DEBUG_INFO, "OCPI: Got active MBR partition device path", DevicePath);
-          FreePool (Mbr);
-          *PartitionDevicePathSize = GetDevicePathSize (DevicePath);
-          return DevicePath;
+          DebugPrintDevicePath (DEBUG_INFO, "OCPI: Got active MBR partition device path", HdDevicePath);
+
+          PartitionDevicePath      = HdDevicePath;
+          *PartitionDevicePathSize = HdDpSize;
+          *PartitionDeviceHandle   = Handles[Index];
+          break;
         }
       }
     }
   }
 
+  FreePool (Handles);
   FreePool (Mbr);
-  return NULL;
+
+  return PartitionDevicePath;
 }
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index c6b4699575c..34b515cb72a 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -37,11 +37,6 @@ typedef enum OC_LEGACY_OS_TYPE_ {
   OcLegacyOsTypeIsoLinux
 } OC_LEGACY_OS_TYPE;
 
-typedef struct {
-  EFI_HANDLE                  FsHandle;
-  EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
-} OPEN_LEGACY_BOOT_CONTEXT;
-
 EFI_STATUS
 InternalGetBiosDiskNumber (
   IN      THUNK_CONTEXT             *ThunkContext,
diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index 9196ba94379..e8bbc3ae88e 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -5,7 +5,6 @@
 
 #include "LegacyBootInternal.h"
 
-
 THUNK_CONTEXT  mThunkContext;
 
 //
@@ -466,7 +465,6 @@ InternalLoadLegacyPbr (
 
   OcLegacyThunkDisconnectEfiGraphics ();
 
-
   //
   // Thunk to real mode and invoke legacy boot sector.
   // If successful, this function will not return.
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index c622c0a09c5..3c20f154003 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -50,17 +50,14 @@ InternalFreePickerEntry (
 
 STATIC
 EFI_STATUS
-SystemActionDoLegacyBoot (
-  IN OUT  OC_PICKER_CONTEXT  *PickerContext,
-  IN      VOID               *ActionContext
+ExternalSystemActionDoLegacyBoot (
+  IN OUT          OC_PICKER_CONTEXT         *PickerContext,
+  IN              EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   )
 {
   EFI_STATUS                 Status;
   EFI_HANDLE                 LoadedImageHandle;
   EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
-  OPEN_LEGACY_BOOT_CONTEXT   *LegacyContext;
-
-  LegacyContext = (OPEN_LEGACY_BOOT_CONTEXT *)ActionContext;
 
   //
   // Load and start legacy OS.
@@ -68,11 +65,11 @@ SystemActionDoLegacyBoot (
   // On Macs, use the Apple legacy interface.
   // On other systems, use the Legacy8259 protocol.
   //
-  DebugPrintDevicePath (DEBUG_INFO, "LEG: Legacy device path", LegacyContext->DevicePath);
+  DebugPrintDevicePath (DEBUG_INFO, "LEG: Legacy device path", DevicePath);
   if (mIsAppleInterfaceSupported) {
     Status = InternalLoadAppleLegacyInterface (
                mImageHandle,
-               LegacyContext->DevicePath,
+               DevicePath,
                &LoadedImageHandle
                );
     if (EFI_ERROR (Status)) {
@@ -109,7 +106,7 @@ SystemActionDoLegacyBoot (
       return Status;
     }
   } else {
-    InternalLoadLegacyPbr (LegacyContext->DevicePath, LegacyContext->FsHandle);
+    InternalLoadLegacyPbr (DevicePath, OcPartitionGetPartitionHandle (DevicePath));
   }
 
   return EFI_SUCCESS;
@@ -185,22 +182,21 @@ OcGetLegacyBootEntries (
     return EFI_NOT_FOUND;
   }
 
-  PickerEntry               = AllocateZeroPool (sizeof (*PickerEntry));
-  PickerEntry->Id           = "legacy_boot";
-  PickerEntry->Name         = "Windows (legacy)";
-  PickerEntry->Path         = NULL;
-  PickerEntry->Arguments    = NULL;
-  PickerEntry->Flavour      = OC_FLAVOUR_WINDOWS;
-  PickerEntry->Tool         = FALSE;
-  PickerEntry->TextMode     = TRUE;
-  PickerEntry->RealPath     = FALSE;
-  PickerEntry->SystemAction = SystemActionDoLegacyBoot;
-
-  OPEN_LEGACY_BOOT_CONTEXT  *contex = (OPEN_LEGACY_BOOT_CONTEXT *)AllocateZeroPool (sizeof (OPEN_LEGACY_BOOT_CONTEXT));
-
-  contex->DevicePath               = DevicePathFromHandle (Device);
-  contex->FsHandle                 = Device;
-  PickerEntry->SystemActionContext = contex;
+  CHAR16  *str2 = ConvertDevicePathToText (DevicePathFromHandle (Device), FALSE, FALSE);
+  CHAR8   *str  = AllocateZeroPool (StrLen (str2) + 1);
+
+  UnicodeStrToAsciiStrS (str2, str, StrLen (str2) + 1);
+
+  PickerEntry                       = AllocateZeroPool (sizeof (*PickerEntry));
+  PickerEntry->Id                   = str;
+  PickerEntry->Name                 = "Windows (legacy)";
+  PickerEntry->Path                 = NULL;
+  PickerEntry->Arguments            = NULL;
+  PickerEntry->Flavour              = OC_FLAVOUR_WINDOWS;
+  PickerEntry->Tool                 = FALSE;
+  PickerEntry->TextMode             = TRUE;
+  PickerEntry->RealPath             = FALSE;
+  PickerEntry->ExternalSystemAction = ExternalSystemActionDoLegacyBoot;
 
   *Entries    = PickerEntry;
   *NumEntries = 1;
diff --git a/Platform/ResetNvramEntry/ResetNvramEntry.c b/Platform/ResetNvramEntry/ResetNvramEntry.c
index dae08cf6f1d..025f53f4325 100644
--- a/Platform/ResetNvramEntry/ResetNvramEntry.c
+++ b/Platform/ResetNvramEntry/ResetNvramEntry.c
@@ -39,8 +39,7 @@ WaitForChime (
 STATIC
 EFI_STATUS
 SystemActionResetNvram (
-  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
-  IN              VOID               *ActionContext
+  IN OUT          OC_PICKER_CONTEXT  *PickerContext
   )
 {
   UINT8  ResetNVRam = 1;
diff --git a/Platform/ToggleSipEntry/ToggleSipEntry.c b/Platform/ToggleSipEntry/ToggleSipEntry.c
index b4092d562de..96255582045 100644
--- a/Platform/ToggleSipEntry/ToggleSipEntry.c
+++ b/Platform/ToggleSipEntry/ToggleSipEntry.c
@@ -32,8 +32,7 @@ STATIC BOOLEAN  mShowCsr;
 STATIC
 EFI_STATUS
 SystemActionSetSip (
-  IN OUT          OC_PICKER_CONTEXT  *Context,
-  IN              VOID               *ActionContext
+  IN OUT          OC_PICKER_CONTEXT  *Context
   )
 {
   EFI_STATUS  Status;

From a0628f0faac22d415561565523784d75d2bd2177 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 13 Aug 2023 20:49:30 -0500
Subject: [PATCH 29/55] OcLegacyThunkLib: Add missing library reference to
 IoLib

---
 Library/OcLegacyThunkLib/OcLegacyThunkLib.inf | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
index ff863551a03..224f8888fb2 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
@@ -46,6 +46,7 @@
 [LibraryClasses]
   BaseMemoryLib
   DebugLib
+  IoLib
   MemoryAllocationLib
   UefiBootServicesTableLib
   UefiLib

From 2e8456e33d514476bb2761d1b9f0e5c2c7a919a6 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 13 Aug 2023 20:55:54 -0500
Subject: [PATCH 30/55] OcLegacyThunkLib: Add missing protocol reference

---
 Library/OcLegacyThunkLib/OcLegacyThunkLib.inf | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
index 224f8888fb2..7f9e9bc8dd6 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.inf
@@ -41,6 +41,7 @@
 
 [Protocols]
   gEfiLegacy8259ProtocolGuid
+  gEfiPciIoProtocolGuid
   gEfiTimerArchProtocolGuid
 
 [LibraryClasses]

From 667d9c338335b31a1fbeedbc2e148312a4b8f52b Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 13 Aug 2023 21:27:14 -0500
Subject: [PATCH 31/55] OpenLegacyBoot: Fix CI build issues

---
 Platform/OpenLegacyBoot/BiosDisk.c       |  4 ++--
 Platform/OpenLegacyBoot/OpenLegacyBoot.c | 13 ++-----------
 2 files changed, 4 insertions(+), 13 deletions(-)

diff --git a/Platform/OpenLegacyBoot/BiosDisk.c b/Platform/OpenLegacyBoot/BiosDisk.c
index cbe7097ff62..8bfccc83d5a 100644
--- a/Platform/OpenLegacyBoot/BiosDisk.c
+++ b/Platform/OpenLegacyBoot/BiosDisk.c
@@ -160,8 +160,8 @@ InternalGetBiosDiskNumber (
     return Status;
   }
 
-  DeviceAddressPacket = (DEVICE_ADDRESS_PACKET *)DeviceAddressPacketAddress;
-  Buffer              = (UINT8 *)DeviceAddressPacketAddress + 0x200;
+  DeviceAddressPacket = (DEVICE_ADDRESS_PACKET *)(UINTN)DeviceAddressPacketAddress;
+  Buffer              = (UINT8 *)(UINTN)DeviceAddressPacketAddress + 0x200;
 
   //
   // Locate disk with matching checksum of first few sectors.
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index 3c20f154003..b5401993df0 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -31,17 +31,9 @@ InternalFreePickerEntry (
     FreePool ((CHAR8 *)Entry->Id);
   }
 
-  if (Entry->Name != NULL) {
+  /*if (Entry->Name != NULL) {
     FreePool ((CHAR8 *)Entry->Name);
-  }
-
-  if (Entry->Path != NULL) {
-    FreePool ((CHAR8 *)Entry->Path);
-  }
-
-  if (Entry->Arguments != NULL) {
-    FreePool ((CHAR8 *)Entry->Arguments);
-  }
+  }*/
 
   if (Entry->Flavour != NULL) {
     FreePool ((CHAR8 *)Entry->Flavour);
@@ -212,7 +204,6 @@ OcFreeLegacyBootEntries (
   IN   UINTN            NumEntries
   )
 {
-  return;
   UINTN  Index;
 
   ASSERT (Entries   != NULL);

From d5de54598c082d5865e3e9b40e73220bf2f29301 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 14 Aug 2023 18:03:35 -0500
Subject: [PATCH 32/55] OpenLegacyBoot: Fix prefix on debug prints

---
 Platform/OpenLegacyBoot/BiosDisk.c          |  6 ++---
 Platform/OpenLegacyBoot/LegacyBootSupport.c | 27 +++++++++++----------
 Platform/OpenLegacyBoot/OpenLegacyBoot.c    | 18 +++++++-------
 3 files changed, 26 insertions(+), 25 deletions(-)

diff --git a/Platform/OpenLegacyBoot/BiosDisk.c b/Platform/OpenLegacyBoot/BiosDisk.c
index 8bfccc83d5a..4fa45a5045e 100644
--- a/Platform/OpenLegacyBoot/BiosDisk.c
+++ b/Platform/OpenLegacyBoot/BiosDisk.c
@@ -57,13 +57,13 @@ BiosDiskReset (
   CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
 
   if (CarryFlag != 0) {
-    DEBUG ((DEBUG_WARN, "LEG: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AL));
+    DEBUG ((DEBUG_WARN, "OLB: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AL));
     if (Regs.H.AL == BIOS_RESET_FAILED) {
       Regs.H.AH = 0x00;
       Regs.H.DL = DriveNumber;
       CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
       if (CarryFlag != 0) {
-        DEBUG ((DEBUG_WARN, "LEG: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AH));
+        DEBUG ((DEBUG_WARN, "OLB: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AH));
         return EFI_DEVICE_ERROR;
       }
     }
@@ -156,7 +156,7 @@ InternalGetBiosDiskNumber (
                                       &DeviceAddressPacketAddress
                                       );
   if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_WARN, "LEG: Failure allocating low memory packet for BIOS disk read - %r\n", Status));
+    DEBUG ((DEBUG_WARN, "OLB: Failure allocating low memory packet for BIOS disk read - %r\n", Status));
     return Status;
   }
 
diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index e8bbc3ae88e..e46b1cf096a 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -182,7 +182,7 @@ InternalLoadAppleLegacyInterface (
       return EFI_INVALID_PARAMETER;
     }
 
-    DebugPrintDevicePath (DEBUG_INFO, "OCB: Legacy disk device path", WholeDiskPath);
+    DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy disk device path", WholeDiskPath);
 
     // TODO: Mark target partition as active on pure MBR and hybrid GPT disks.
     // Macs only boot the active partition.
@@ -227,7 +227,7 @@ InternalLoadAppleLegacyInterface (
         UnicodeDevicePath = ConvertDevicePathToText (LegacyDevicePaths[Index], FALSE, FALSE);
         DEBUG ((
           DEBUG_INFO,
-          "OCB: Loaded Apple legacy interface at dp %s - %r\n",
+          "OLB: Loaded Apple legacy interface at dp %s - %r\n",
           UnicodeDevicePath != NULL ? UnicodeDevicePath : L"<null>",
           Status
           ));
@@ -271,7 +271,7 @@ InternalGetPartitionLegacyOsType (
     return OcLegacyOsTypeNone;
   }
 
-  DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading MBR for disk", DevicePath);
+  DebugPrintDevicePath (DEBUG_INFO, "OLB: Reading MBR for disk", DevicePath);
 
   DiskHandle = OcPartitionGetDiskHandle (DevicePath);
   if (DiskHandle == NULL) {
@@ -280,7 +280,7 @@ InternalGetPartitionLegacyOsType (
 
   Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
   if (Mbr == NULL) {
-    DEBUG ((DEBUG_INFO, "OCB: Disk does not contain a valid MBR partition table\n"));
+    DEBUG ((DEBUG_INFO, "OLB: Disk does not contain a valid MBR partition table\n"));
     return OcLegacyOsTypeNone;
   }
 
@@ -293,7 +293,7 @@ InternalGetPartitionLegacyOsType (
     //
     // Retrieve the first sector of the partition.
     //
-    DebugPrintDevicePath (DEBUG_INFO, "OCB: Reading PBR for partition", DevicePath);
+    DebugPrintDevicePath (DEBUG_INFO, "OLB: Reading PBR for partition", DevicePath);
     Status = OcDiskInitializeContext (
                &DiskContext,
                PartitionHandle,
@@ -306,7 +306,7 @@ InternalGetPartitionLegacyOsType (
     MbrSize = ALIGN_VALUE (sizeof (*Mbr), DiskContext.BlockSize);
     Mbr     = (MASTER_BOOT_RECORD *)AllocatePool (MbrSize);
     if (Mbr == NULL) {
-      DEBUG ((DEBUG_INFO, "OCB: Buffer allocation error\n"));
+      DEBUG ((DEBUG_INFO, "OLB: Buffer allocation error\n"));
       return OcLegacyOsTypeNone;
     }
 
@@ -322,7 +322,7 @@ InternalGetPartitionLegacyOsType (
     }
   }
 
-  DebugPrintHexDump (DEBUG_INFO, "OCB: MbrHEX", Mbr->BootStrapCode, sizeof (Mbr->BootStrapCode));
+  DebugPrintHexDump (DEBUG_INFO, "OLB: MbrHEX", Mbr->BootStrapCode, sizeof (Mbr->BootStrapCode));
 
   //
   // Validate signature in MBR.
@@ -346,7 +346,7 @@ InternalGetPartitionLegacyOsType (
     LegacyOsType = OcLegacyOsTypeIsoLinux;
   } else {
     LegacyOsType = OcLegacyOsTypeNone;
-    DEBUG ((DEBUG_INFO, "OCB: Unknown legacy bootsector signature\n"));
+    DEBUG ((DEBUG_INFO, "OLB: Unknown legacy bootsector signature\n"));
   }
 
   FreePool (Mbr);
@@ -381,7 +381,7 @@ InternalLoadLegacyPbr (
                   (VOID **)&Legacy8259
                   );
   if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_INFO, "LEG: Could not locate Legacy8259 protocol\n"));
+    DEBUG ((DEBUG_INFO, "OLB: Could not locate Legacy8259 protocol\n"));
     return Status;
   }
 
@@ -400,7 +400,7 @@ InternalLoadLegacyPbr (
   PbrSize = ALIGN_VALUE (sizeof (*Pbr), DiskContext.BlockSize);
   Pbr     = (MASTER_BOOT_RECORD *)AllocatePool (PbrSize);
   if (Pbr == NULL) {
-    DEBUG ((DEBUG_INFO, "LEG: Buffer allocation error\n"));
+    DEBUG ((DEBUG_INFO, "OLB: Buffer allocation error\n"));
     return EFI_OUT_OF_RESOURCES;
   }
 
@@ -415,7 +415,7 @@ InternalLoadLegacyPbr (
     return Status;
   }
 
-  DebugPrintHexDump (DEBUG_INFO, "LEG: PbrHEX", (UINT8 *)Pbr, sizeof (*Pbr));
+  DebugPrintHexDump (DEBUG_INFO, "OLB: PbrHEX", (UINT8 *)Pbr, sizeof (*Pbr));
 
   //
   // Retrieve MBR from disk.
@@ -428,7 +428,7 @@ InternalLoadLegacyPbr (
 
   Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
   if (Mbr == NULL) {
-    DEBUG ((DEBUG_INFO, "LEG: Disk does not contain a valid MBR partition table\n"));
+    DEBUG ((DEBUG_INFO, "OLB: Disk does not contain a valid MBR partition table\n"));
     FreePool (Pbr);
     return EFI_INVALID_PARAMETER;
   }
@@ -461,9 +461,10 @@ InternalLoadLegacyPbr (
   CopyMem (PbrPtr, Pbr, sizeof (*Pbr));
   CopyMem (MbrPtr, Mbr, sizeof (*Mbr));
 
-  DebugPrintHexDump (DEBUG_INFO, "LEG: PbrPtr", (UINT8 *)PbrPtr, sizeof (*PbrPtr));
+  DebugPrintHexDump (DEBUG_INFO, "OLB: PbrPtr", (UINT8 *)PbrPtr, sizeof (*PbrPtr));
 
   OcLegacyThunkDisconnectEfiGraphics ();
+  ReleaseUsbOwnership ();
 
   //
   // Thunk to real mode and invoke legacy boot sector.
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index b5401993df0..1ba0e207617 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -57,7 +57,7 @@ ExternalSystemActionDoLegacyBoot (
   // On Macs, use the Apple legacy interface.
   // On other systems, use the Legacy8259 protocol.
   //
-  DebugPrintDevicePath (DEBUG_INFO, "LEG: Legacy device path", DevicePath);
+  DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy device path", DevicePath);
   if (mIsAppleInterfaceSupported) {
     Status = InternalLoadAppleLegacyInterface (
                mImageHandle,
@@ -65,7 +65,7 @@ ExternalSystemActionDoLegacyBoot (
                &LoadedImageHandle
                );
     if (EFI_ERROR (Status)) {
-      DEBUG ((DEBUG_WARN, "LEG: Failure while loading Apple legacy interface - %r\n", Status));
+      DEBUG ((DEBUG_WARN, "OLB: Failure while loading Apple legacy interface - %r\n", Status));
       return Status;
     }
 
@@ -75,7 +75,7 @@ ExternalSystemActionDoLegacyBoot (
                     (VOID **)&LoadedImage
                     );
     if (EFI_ERROR (Status)) {
-      DEBUG ((DEBUG_WARN, "LEG: Failure while loading Apple legacy interface - %r\n", Status));
+      DEBUG ((DEBUG_WARN, "OLB: Failure while loading Apple legacy interface - %r\n", Status));
       return Status;
     }
 
@@ -94,7 +94,7 @@ ExternalSystemActionDoLegacyBoot (
       ));
     Status = gBS->StartImage (LoadedImageHandle, NULL, NULL);
     if (EFI_ERROR (Status)) {
-      DEBUG ((DEBUG_WARN, "LEG: Failure while starting Apple legacy interface - %r\n", Status));
+      DEBUG ((DEBUG_WARN, "OLB: Failure while starting Apple legacy interface - %r\n", Status));
       return Status;
     }
   } else {
@@ -139,7 +139,7 @@ OcGetLegacyBootEntries (
                    (VOID **)&FileSystem
                    );
    if (EFI_ERROR (Status)) {
-     DEBUG ((DEBUG_WARN, "LEG: Missing filesystem - %r\n", Status));
+     DEBUG ((DEBUG_WARN, "OLB: Missing filesystem - %r\n", Status));
      return Status;
    }
 
@@ -151,7 +151,7 @@ OcGetLegacyBootEntries (
                           &RootDirectory
                           );
    if (EFI_ERROR (Status)) {
-     DEBUG ((DEBUG_WARN, "LEG: Invalid root volume - %r\n", Status));
+     DEBUG ((DEBUG_WARN, "OLB: Invalid root volume - %r\n", Status));
      return Status;
    }
 
@@ -161,7 +161,7 @@ OcGetLegacyBootEntries (
   // Disallow all but NTFS filesystems.
   //
   // if ((FileSystemPolicy & OC_SCAN_ALLOW_FS_NTFS) != 0) {
-  //   DEBUG ((DEBUG_INFO, "LEG: Not scanning non-NTFS filesystem\n"));
+  //   DEBUG ((DEBUG_INFO, "OLB: Not scanning non-NTFS filesystem\n"));
   //  Status = EFI_NOT_FOUND;
   // }
 
@@ -242,11 +242,11 @@ UefiMain (
 
   Status = InternalIsLegacyInterfaceSupported (&mIsAppleInterfaceSupported);
   if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_WARN, "LEG: Legacy boot interface is supported on this system\n"));
+    DEBUG ((DEBUG_WARN, "OLB: Legacy boot interface is supported on this system\n"));
     return Status;
   }
 
-  DEBUG ((DEBUG_INFO, "LEG: Apple legacy interface: %d\n", mIsAppleInterfaceSupported));
+  DEBUG ((DEBUG_INFO, "OLB: Apple legacy interface: %d\n", mIsAppleInterfaceSupported));
 
   Status = gBS->InstallMultipleProtocolInterfaces (
                   &ImageHandle,

From 387adeb564cc482dc81d47b80a16d351fb724369 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 14 Aug 2023 19:34:52 -0500
Subject: [PATCH 33/55] OpenLegacyBoot: Fix previous commit

---
 Platform/OpenLegacyBoot/LegacyBootSupport.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index e46b1cf096a..7d32ad5f422 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -464,7 +464,6 @@ InternalLoadLegacyPbr (
   DebugPrintHexDump (DEBUG_INFO, "OLB: PbrPtr", (UINT8 *)PbrPtr, sizeof (*PbrPtr));
 
   OcLegacyThunkDisconnectEfiGraphics ();
-  ReleaseUsbOwnership ();
 
   //
   // Thunk to real mode and invoke legacy boot sector.

From e03a5773aec04a1608841775bcf719ed20fe23d0 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Thu, 17 Aug 2023 17:31:50 -0500
Subject: [PATCH 34/55] OpenLegacyBoot: Implement active partition switching

---
 Include/Acidanthera/Library/OcFileLib.h      |  63 +++++-
 Library/OcFileLib/DiskMisc.c                 | 226 +++++++++++++++++--
 Platform/OpenLegacyBoot/LegacyBootInternal.h |   3 +-
 Platform/OpenLegacyBoot/LegacyBootSupport.c  |  65 ++++--
 Platform/OpenLegacyBoot/OpenLegacyBoot.c     |   2 +-
 5 files changed, 310 insertions(+), 49 deletions(-)

diff --git a/Include/Acidanthera/Library/OcFileLib.h b/Include/Acidanthera/Library/OcFileLib.h
index a86fbd5d9b8..5295fc80e9e 100644
--- a/Include/Acidanthera/Library/OcFileLib.h
+++ b/Include/Acidanthera/Library/OcFileLib.h
@@ -591,6 +591,24 @@ OcDiskRead (
   OUT VOID             *Buffer
   );
 
+/**
+  Write information to disk.
+
+  @param[in]  Context     Disk I/O context.
+  @param[in]  Lba         LBA number to write to.
+  @param[in]  BufferSize  Buffer size allocated in Buffer.
+  @param[out] Buffer      Buffer containing data to write.
+
+  @retval EFI_SUCCESS on success.
+**/
+EFI_STATUS
+OcDiskWrite (
+  IN OC_DISK_CONTEXT  *Context,
+  IN UINT64           Lba,
+  IN UINTN            BufferSize,
+  IN VOID             *Buffer
+  );
+
 /**
   OC partition list.
 **/
@@ -630,17 +648,54 @@ OcGetGptPartitionEntry (
 /**
   Retrieve the disk MBR table, if applicable.
 
-  @param[in]  DiskHandle   Disk device handle to retrive MBR partition table from.
-  @param[in]  UseBlockIo2  Use 2nd revision of Block I/O if available.
+  @param[in]  DiskHandle      Disk device handle to retrive MBR partition table from.
+  @param[in]  CheckPartitions Check partition layout. This should be FALSE for a PBR.
 
-  @retval partition entry list or NULL.
+  @retval MBR partition table or NULL.
 **/
 MASTER_BOOT_RECORD *
 OcGetDiskMbrTable (
   IN EFI_HANDLE  DiskHandle,
-  IN BOOLEAN     UseBlockIo2
+  IN BOOLEAN     CheckPartitions
+  );
+
+/**
+  Retrieve the MBR partition index for the specified partition.
+
+  @param[in]  PartitionHandle   Partition device handle to retrieve MBR partition index for.
+  @param[out] PartitionIndex    Pointer to store partition index in.
+
+  @retval EFI_SUCCESS on success.
+**/
+EFI_STATUS
+OcDiskGetMbrPartitionIndex (
+  IN  EFI_HANDLE  PartitionHandle,
+  OUT UINT8       *PartitionIndex
   );
 
+/**
+  Mark specified MBR partition as active.
+
+  @param[in]  DiskHandle        Disk device handle containing MBR partition table
+  @param[in]  PartitionIndex    MBR partition index.
+
+  @retval EFI_SUCCESS on success.
+**/
+EFI_STATUS
+OcDiskMarkMbrPartitionActive (
+  IN  EFI_HANDLE  DiskHandle,
+  IN  UINT8       PartitionIndex
+  );
+
+/**
+  Locate the disk's active MBR partition.
+
+  @param[in]  DiskDevicePath            The Device Path of the disk to scan.
+  @param[out] PartitionDevicePathSize   The size of the returned Device Path.
+  @param[out] PartitionDeviceHandle     Device handle of the returned partition.
+
+  @return The device path protocol from the discovered handle or NULL.
+**/
 EFI_DEVICE_PATH_PROTOCOL *
 OcDiskFindActiveMbrPartitionPath (
   IN  EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index cf590d05db3..c5eeed47b46 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -40,6 +40,8 @@ STATIC EFI_GUID  mInternalPartitionEntryProtocolGuid = {
   0x9FC6B19, 0xB8A1, 0x4A01, { 0x8D, 0xB1, 0x87, 0x94, 0xE7, 0x63, 0x4C, 0xA5 }
 };
 
+#define MBR_PARTITION_ACTIVE  0x80
+
 EFI_STATUS
 OcDiskInitializeContext (
   OUT OC_DISK_CONTEXT  *Context,
@@ -49,6 +51,9 @@ OcDiskInitializeContext (
 {
   EFI_STATUS  Status;
 
+  ASSERT (Context != NULL);
+  ASSERT (DiskHandle != NULL);
+
   //
   // Retrieve the Block I/O protocol.
   //
@@ -142,6 +147,41 @@ OcDiskRead (
   return Status;
 }
 
+EFI_STATUS
+OcDiskWrite (
+  IN OC_DISK_CONTEXT  *Context,
+  IN UINT64           Lba,
+  IN UINTN            BufferSize,
+  IN VOID             *Buffer
+  )
+{
+  EFI_STATUS  Status;
+
+  ASSERT (Context->BlockIo != NULL || Context->BlockIo2 != NULL);
+  ASSERT ((BufferSize & (Context->BlockSize - 1)) == 0);
+
+  if (Context->BlockIo2 != NULL) {
+    Status = Context->BlockIo2->WriteBlocksEx (
+                                  Context->BlockIo2,
+                                  Context->MediaId,
+                                  Lba,
+                                  NULL,
+                                  BufferSize,
+                                  Buffer
+                                  );
+  } else {
+    Status = Context->BlockIo->WriteBlocks (
+                                 Context->BlockIo,
+                                 Context->MediaId,
+                                 Lba,
+                                 BufferSize,
+                                 Buffer
+                                 );
+  }
+
+  return Status;
+}
+
 STATIC
 VOID
 InternalDebugPrintPartitionEntry (
@@ -723,7 +763,7 @@ OcGetGptPartitionEntry (
 MASTER_BOOT_RECORD *
 OcGetDiskMbrTable (
   IN EFI_HANDLE  DiskHandle,
-  IN BOOLEAN     UseBlockIo2
+  IN BOOLEAN     CheckPartitions
   )
 {
   EFI_STATUS          Status;
@@ -741,7 +781,7 @@ OcGetDiskMbrTable (
   Status = OcDiskInitializeContext (
              &DiskContext,
              DiskHandle,
-             UseBlockIo2
+             TRUE
              );
   if (EFI_ERROR (Status)) {
     return NULL;
@@ -775,27 +815,178 @@ OcGetDiskMbrTable (
     return NULL;
   }
 
-  if (  (Mbr->Partition[0].OSIndicator == PMBR_GPT_PARTITION)
-     && (*((UINT32 *)Mbr->Partition[0].StartingLBA) == 0x01)
-     && (*((UINT32 *)Mbr->Partition[0].SizeInLBA) != 0))
-  {
-    IsProtectiveMbr = TRUE;
-    for (Index = 1; Index < MAX_MBR_PARTITIONS; Index++) {
-      if ((*((UINT32 *)Mbr->Partition[Index].StartingLBA) != 0) || (*((UINT32 *)Mbr->Partition[Index].SizeInLBA) != 0)) {
-        IsProtectiveMbr = FALSE;
-        break;
+  if (CheckPartitions) {
+    if (  (Mbr->Partition[0].OSIndicator == PMBR_GPT_PARTITION)
+       && (*((UINT32 *)Mbr->Partition[0].StartingLBA) == 0x01)
+       && (*((UINT32 *)Mbr->Partition[0].SizeInLBA) != 0))
+    {
+      IsProtectiveMbr = TRUE;
+      for (Index = 1; Index < MAX_MBR_PARTITIONS; Index++) {
+        if ((*((UINT32 *)Mbr->Partition[Index].StartingLBA) != 0) || (*((UINT32 *)Mbr->Partition[Index].SizeInLBA) != 0)) {
+          IsProtectiveMbr = FALSE;
+          break;
+        }
       }
-    }
 
-    if (IsProtectiveMbr) {
-      FreePool (Mbr);
-      return NULL;
+      if (IsProtectiveMbr) {
+        FreePool (Mbr);
+        return NULL;
+      }
     }
   }
 
   return Mbr;
 }
 
+EFI_STATUS
+OcDiskGetMbrPartitionIndex (
+  IN  EFI_HANDLE  PartitionHandle,
+  OUT UINT8       *PartitionIndex
+  )
+{
+  EFI_STATUS                   Status;
+  MASTER_BOOT_RECORD           *Mbr;
+  EFI_DEVICE_PATH_PROTOCOL     *DevicePath;
+  EFI_HANDLE                   DiskHandle;
+  CONST HARDDRIVE_DEVICE_PATH  *HdNode;
+  UINT8                        Index;
+
+  ASSERT (PartitionHandle != NULL);
+  ASSERT (PartitionIndex != NULL);
+
+  //
+  // Retrieve the partition Device Path information.
+  //
+  DevicePath = DevicePathFromHandle (PartitionHandle);
+  if (DevicePath == NULL) {
+    DEBUG ((DEBUG_INFO, "OCPI: Failed to retrieve Device Path\n"));
+    return EFI_UNSUPPORTED;
+  }
+
+  HdNode = (HARDDRIVE_DEVICE_PATH *)(
+                                     FindDevicePathNodeWithType (
+                                       DevicePath,
+                                       MEDIA_DEVICE_PATH,
+                                       MEDIA_HARDDRIVE_DP
+                                       )
+                                     );
+  if (HdNode == NULL) {
+    DEBUG ((DEBUG_INFO, "OCPI: Device Path does not describe a partition\n"));
+    return EFI_UNSUPPORTED;
+  }
+
+  DiskHandle = OcPartitionGetDiskHandle (DevicePath);
+  if (DiskHandle == NULL) {
+    return EFI_UNSUPPORTED;
+  }
+
+  //
+  // Get MBR from partition's disk.
+  //
+  Mbr = OcGetDiskMbrTable (
+          DiskHandle,
+          TRUE
+          );
+  if (Mbr == NULL) {
+    DEBUG ((DEBUG_INFO, "OCPI: Disk does not have an MBR partition table\n"));
+    return EFI_UNSUPPORTED;
+  }
+
+  Status = EFI_NOT_FOUND;
+  for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
+    if (  (*((UINT32 *)Mbr->Partition[Index].StartingLBA) == HdNode->PartitionStart)
+       && (*((UINT32 *)Mbr->Partition[Index].SizeInLBA) == HdNode->PartitionSize))
+    {
+      *PartitionIndex = Index;
+      Status          = EFI_SUCCESS;
+      break;
+    }
+  }
+
+  FreePool (Mbr);
+
+  return Status;
+}
+
+EFI_STATUS
+OcDiskMarkMbrPartitionActive (
+  IN  EFI_HANDLE  DiskHandle,
+  IN  UINT8       PartitionIndex
+  )
+{
+  EFI_STATUS          Status;
+  MASTER_BOOT_RECORD  *Mbr;
+  UINTN               MbrSize;
+  UINTN               Index;
+  OC_DISK_CONTEXT     DiskContext;
+
+  ASSERT (DiskHandle != NULL);
+  ASSERT (PartitionIndex < MAX_MBR_PARTITIONS);
+
+  //
+  // Read first sector containing MBR table.
+  //
+  Status = OcDiskInitializeContext (
+             &DiskContext,
+             DiskHandle,
+             TRUE
+             );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  MbrSize = ALIGN_VALUE (sizeof (*Mbr), DiskContext.BlockSize);
+  Mbr     = (MASTER_BOOT_RECORD *)AllocatePool (MbrSize);
+  if (Mbr == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  Status = OcDiskRead (
+             &DiskContext,
+             0,
+             MbrSize,
+             Mbr
+             );
+  if (EFI_ERROR (Status)) {
+    FreePool (Mbr);
+    return Status;
+  }
+
+  //
+  // Validate MBR signatures.
+  //
+  // If MBR is a protective one (as part of a GPT disk), ignore.
+  // Protective MBR is defined as a single partition of type 0xEE, other three partitions are to be zero.
+  //
+  if (Mbr->Signature != MBR_SIGNATURE) {
+    FreePool (Mbr);
+    return EFI_UNSUPPORTED;
+  }
+
+  //
+  // Mark desired partition as active.
+  //
+  for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
+    Mbr->Partition[Index].BootIndicator = 0x00;
+  }
+
+  Mbr->Partition[PartitionIndex].BootIndicator = MBR_PARTITION_ACTIVE;
+
+  //
+  // Write MBR to disk.
+  //
+  Status = OcDiskWrite (
+             &DiskContext,
+             0,
+             MbrSize,
+             Mbr
+             );
+
+  FreePool (Mbr);
+
+  return Status;
+}
+
 EFI_DEVICE_PATH_PROTOCOL *
 OcDiskFindActiveMbrPartitionPath (
   IN  EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
@@ -858,7 +1049,7 @@ OcDiskFindActiveMbrPartitionPath (
 
   Mbr = OcGetDiskMbrTable (
           DiskHandle,
-          HasBlockIo2
+          TRUE
           );
   if (Mbr == NULL) {
     return NULL;
@@ -870,8 +1061,9 @@ OcDiskFindActiveMbrPartitionPath (
   //
   ActivePartition = -1;
   for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
-    if (Mbr->Partition[Index].BootIndicator == 0x80) {
+    if (Mbr->Partition[Index].BootIndicator == MBR_PARTITION_ACTIVE) {
       ActivePartition = (INT32)Index;
+      break;
     }
   }
 
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index 34b515cb72a..735a5976672 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -63,8 +63,7 @@ InternalGetPartitionLegacyOsType (
 
 EFI_STATUS
 InternalLoadLegacyPbr (
-  IN  EFI_DEVICE_PATH_PROTOCOL  *PartitionPath,
-  IN  EFI_HANDLE                PartitionHandle
+  IN  EFI_DEVICE_PATH_PROTOCOL  *PartitionPath
   );
 
 #endif // LEGACY_BOOT_INTERNAL_H
diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index 7d32ad5f422..ad9638ec12e 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -168,6 +168,9 @@ InternalLoadAppleLegacyInterface (
   )
 {
   EFI_STATUS                Status;
+  EFI_HANDLE                DiskHandle;
+  EFI_HANDLE                PartitionHandle;
+  UINT8                     PartitionIndex;
   EFI_DEVICE_PATH_PROTOCOL  *WholeDiskPath;
   EFI_DEVICE_PATH_PROTOCOL  **LegacyDevicePaths;
   CHAR16                    *UnicodeDevicePath;
@@ -184,8 +187,28 @@ InternalLoadAppleLegacyInterface (
 
     DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy disk device path", WholeDiskPath);
 
-    // TODO: Mark target partition as active on pure MBR and hybrid GPT disks.
-    // Macs only boot the active partition.
+    //
+    // Mark target partition as active.
+    //
+    DiskHandle = OcPartitionGetDiskHandle (HdDevicePath);
+    if (DiskHandle == NULL) {
+      return EFI_INVALID_PARAMETER;
+    }
+
+    PartitionHandle = OcPartitionGetPartitionHandle (HdDevicePath);
+    if (PartitionHandle == NULL) {
+      return EFI_INVALID_PARAMETER;
+    }
+
+    Status = OcDiskGetMbrPartitionIndex (PartitionHandle, &PartitionIndex);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+
+    Status = OcDiskMarkMbrPartitionActive (DiskHandle, PartitionIndex);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
 
     //
     // Set BootCampHD variable pointing to target disk.
@@ -356,16 +379,15 @@ InternalGetPartitionLegacyOsType (
 
 EFI_STATUS
 InternalLoadLegacyPbr (
-  IN  EFI_DEVICE_PATH_PROTOCOL  *PartitionPath,
-  IN  EFI_HANDLE                PartitionHandle
+  IN  EFI_DEVICE_PATH_PROTOCOL  *PartitionPath
   )
 {
   EFI_STATUS          Status;
   EFI_HANDLE          DiskHandle;
+  EFI_HANDLE          PartitionHandle;
   MASTER_BOOT_RECORD  *Mbr;
   MASTER_BOOT_RECORD  *Pbr;
-  UINTN               PbrSize;
-  OC_DISK_CONTEXT     DiskContext;
+  UINT8               PartitionIndex;
 
   IA32_REGISTER_SET         Regs;
   MASTER_BOOT_RECORD        *MbrPtr = (MASTER_BOOT_RECORD *)0x0600;
@@ -386,30 +408,21 @@ InternalLoadLegacyPbr (
   }
 
   //
-  // Retrieve the PBR from partition.
+  // Retrieve the PBR from partition and partition index.
   //
-  Status = OcDiskInitializeContext (
-             &DiskContext,
-             PartitionHandle,
-             TRUE
-             );
-  if (EFI_ERROR (Status)) {
-    return Status;
+  PartitionHandle = OcPartitionGetPartitionHandle (PartitionPath);
+  if (PartitionHandle == NULL) {
+    DEBUG ((DEBUG_INFO, "OLB: Could not locate partition handle\n"));
+    return EFI_INVALID_PARAMETER;
   }
 
-  PbrSize = ALIGN_VALUE (sizeof (*Pbr), DiskContext.BlockSize);
-  Pbr     = (MASTER_BOOT_RECORD *)AllocatePool (PbrSize);
+  Pbr = OcGetDiskMbrTable (PartitionHandle, FALSE);
   if (Pbr == NULL) {
-    DEBUG ((DEBUG_INFO, "OLB: Buffer allocation error\n"));
-    return EFI_OUT_OF_RESOURCES;
+    DEBUG ((DEBUG_INFO, "OLB: Partition does not contain a valid PBR\n"));
+    return EFI_INVALID_PARAMETER;
   }
 
-  Status = OcDiskRead (
-             &DiskContext,
-             0,
-             PbrSize,
-             Pbr
-             );
+  Status = OcDiskGetMbrPartitionIndex (PartitionHandle, &PartitionIndex);
   if (EFI_ERROR (Status)) {
     FreePool (Pbr);
     return Status;
@@ -433,6 +446,8 @@ InternalLoadLegacyPbr (
     return EFI_INVALID_PARAMETER;
   }
 
+  DebugPrintHexDump (DEBUG_INFO, "OLB: MbrHEX", (UINT8 *)Mbr, sizeof (*Mbr));
+
   //
   // Create and initialize thunk structures.
   //
@@ -472,7 +487,7 @@ InternalLoadLegacyPbr (
   ZeroMem (&Regs, sizeof (Regs));
 
   Regs.H.DL = 0x80;
-  Regs.X.SI = (UINT16)(UINTN)&MbrPtr->Partition[2];
+  Regs.X.SI = (UINT16)(UINTN)&MbrPtr->Partition[PartitionIndex];
   OcLegacyThunkFarCall86 (
     &mThunkContext,
     Legacy8259,
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index 1ba0e207617..8b07e685267 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -98,7 +98,7 @@ ExternalSystemActionDoLegacyBoot (
       return Status;
     }
   } else {
-    InternalLoadLegacyPbr (DevicePath, OcPartitionGetPartitionHandle (DevicePath));
+    InternalLoadLegacyPbr (DevicePath);
   }
 
   return EFI_SUCCESS;

From ed62e4ed04ccf338c8100bbda37a5f4ed4f13793 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 15:07:33 -0500
Subject: [PATCH 35/55] OcFileLib: Add El-Torito read function

---
 Include/Acidanthera/Library/OcFileLib.h | 18 ++++++-
 Library/OcFileLib/DiskMisc.c            | 68 ++++++++++++++++++++++++-
 2 files changed, 83 insertions(+), 3 deletions(-)

diff --git a/Include/Acidanthera/Library/OcFileLib.h b/Include/Acidanthera/Library/OcFileLib.h
index 5295fc80e9e..4c45c643a70 100644
--- a/Include/Acidanthera/Library/OcFileLib.h
+++ b/Include/Acidanthera/Library/OcFileLib.h
@@ -522,7 +522,7 @@ OcPartitionGetPartitionHandle (
 /**
   Check if disk is a CD-ROM device.
 
-  @param[in] HdDevicePath  The Device Path of the disk.
+  @param[in] DiskDevicePath  The Device Path of the disk.
 
   @retval Device Path or NULL
 **/
@@ -531,6 +531,22 @@ OcIsDiskCdRom (
   IN EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath
   );
 
+/**
+  Read El-Torito boot sector from CD-ROM device.
+
+  @param[in]  DiskDevicePath  The Device Path of the disk.
+  @param[out] Buffer          Pointer to pool-allocated buffer containing the boot sector data.
+  @param[out] BufferSize      Size of Buffer.
+
+  @retval EFI_SUCCESS on success.
+**/
+EFI_STATUS
+OcDiskReadElTorito (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
+  OUT UINT8                     **Buffer,
+  OUT UINTN                     *BufferSize
+  );
+
 /**
   Locate the disk's EFI System Partition.
 
diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index c5eeed47b46..9008d8124b7 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -301,8 +301,6 @@ OcDiskGetDevicePath (
     if (HdNode == NULL) {
       return NULL;
     }
-
-    DEBUG ((DEBUG_INFO, "got cdrom\n"));
   }
 
   PrefixPath = DuplicateDevicePath (HdDevicePath);
@@ -390,6 +388,72 @@ OcIsDiskCdRom (
   return FALSE;
 }
 
+EFI_STATUS
+OcDiskReadElTorito (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,
+  OUT UINT8                     **Buffer,
+  OUT UINTN                     *BufferSize
+  )
+{
+  EFI_STATUS  Status;
+  UINT8       *BootBuffer;
+  UINTN       BootBufferSize;
+
+  CDROM_DEVICE_PATH  *CdNode;
+  EFI_HANDLE         DiskHandle;
+  OC_DISK_CONTEXT    DiskContext;
+
+  ASSERT (DiskDevicePath != NULL);
+  ASSERT (Buffer != NULL);
+  ASSERT (BufferSize != NULL);
+
+  //
+  // Retrieve the CD-ROM Device Path information.
+  //
+  CdNode = (CDROM_DEVICE_PATH *)(
+                                 FindDevicePathNodeWithType (
+                                   DiskDevicePath,
+                                   MEDIA_DEVICE_PATH,
+                                   MEDIA_CDROM_DP
+                                   )
+                                 );
+  if (CdNode == NULL) {
+    DEBUG ((DEBUG_INFO, "OCPI: Device Path does not describe a CD-ROM\n"));
+    return EFI_UNSUPPORTED;
+  }
+
+  DiskHandle = OcPartitionGetDiskHandle (DiskDevicePath);
+
+  Status = OcDiskInitializeContext (&DiskContext, DiskHandle, TRUE);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // TODO: Unclear whether the sector size here is the native CD size 2048 or 512.
+  //
+  BootBufferSize = CdNode->PartitionSize * DiskContext.BlockSize;
+  BootBuffer     = AllocatePool (BootBufferSize);
+  if (BootBuffer == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  Status = OcDiskRead (
+             &DiskContext,
+             CdNode->PartitionStart,
+             BootBufferSize,
+             BootBuffer
+             );
+  if (EFI_ERROR (Status)) {
+    FreePool (BootBuffer);
+    return Status;
+  }
+
+  *Buffer     = BootBuffer;
+  *BufferSize = BootBufferSize;
+  return EFI_SUCCESS;
+}
+
 EFI_DEVICE_PATH_PROTOCOL *
 OcDiskFindSystemPartitionPath (
   IN  CONST EFI_DEVICE_PATH_PROTOCOL  *DiskDevicePath,

From c70ad782c3a75a59ee2943e273335aea6197a8ce Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 15:09:01 -0500
Subject: [PATCH 36/55] OpenLegacyBoot: Switch to Block I/O for legacy
 detection

---
 .../Acidanthera/Library/OcBootManagementLib.h |  12 +-
 .../OcBootManagementLib/BootEntryManagement.c |  17 +-
 Platform/OpenLegacyBoot/LegacyBootInternal.h  |   7 +-
 Platform/OpenLegacyBoot/LegacyBootSupport.c   | 108 +++++------
 Platform/OpenLegacyBoot/OpenLegacyBoot.c      | 167 ++++++++++--------
 5 files changed, 160 insertions(+), 151 deletions(-)

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index 0f7ea2518fe..33fb388be85 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -200,8 +200,8 @@ EFI_STATUS
 typedef
 EFI_STATUS
 (*OC_BOOT_EXTERNAL_SYSTEM_ACTION) (
-  IN OUT          OC_PICKER_CONTEXT         *PickerContext,
-  IN              EFI_DEVICE_PATH_PROTOCOL  *DevicePath
+  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
+  IN              VOID               *ActionContext
   );
 
 /**
@@ -227,6 +227,10 @@ typedef struct OC_BOOT_ENTRY_ {
   //
   OC_BOOT_EXTERNAL_SYSTEM_ACTION    ExternalSystemAction;
   //
+  // Action to perform on execution. Only valid for external boot system entries.
+  //
+  VOID                              *ExternalSystemActionContext;
+  //
   // Id under which to save entry as default.
   //
   CHAR16                            *Id;
@@ -626,6 +630,10 @@ typedef struct {
   // External boot system action. Boot Entry Protocol only. Optional.
   //
   OC_BOOT_EXTERNAL_SYSTEM_ACTION    ExternalSystemAction;
+  //
+  // External boot system action context. Boot Entry Protocol only. Optional.
+  //
+  VOID                              *ExternalSystemActionContext;
 } OC_PICKER_ENTRY;
 
 /**
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 9fbe2a2ccb6..f9b7bda3d73 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -720,16 +720,11 @@ InternalAddBootEntryFromCustomEntry (
     ));
 
   if (CustomEntry->ExternalSystemAction) {
-    BootEntry->Type                 = OC_BOOT_EXTERNAL_SYSTEM;
-    BootEntry->ExternalSystemAction = CustomEntry->ExternalSystemAction;
-    BootEntry->AudioBasePath        = CustomEntry->AudioBasePath;
-    BootEntry->AudioBaseType        = CustomEntry->AudioBaseType;
-    BootEntry->DevicePath           = DevicePathFromHandle (FileSystem->Handle);
-
-    if (BootEntry->DevicePath == NULL) {
-      FreeBootEntry (BootEntry);
-      return EFI_OUT_OF_RESOURCES;
-    }
+    BootEntry->Type                        = OC_BOOT_EXTERNAL_SYSTEM;
+    BootEntry->ExternalSystemAction        = CustomEntry->ExternalSystemAction;
+    BootEntry->ExternalSystemActionContext = CustomEntry->ExternalSystemActionContext;
+    BootEntry->AudioBasePath               = CustomEntry->AudioBasePath;
+    BootEntry->AudioBaseType               = CustomEntry->AudioBaseType;
   } else if (CustomEntry->SystemAction) {
     BootEntry->Type          = OC_BOOT_SYSTEM;
     BootEntry->SystemAction  = CustomEntry->SystemAction;
@@ -2516,7 +2511,7 @@ OcLoadBootEntry (
 
   if ((BootEntry->Type & OC_BOOT_EXTERNAL_SYSTEM) != 0) {
     ASSERT (BootEntry->ExternalSystemAction != NULL);
-    return BootEntry->ExternalSystemAction (Context, BootEntry->DevicePath);
+    return BootEntry->ExternalSystemAction (Context, BootEntry->ExternalSystemActionContext);
   }
 
   if ((BootEntry->Type & OC_BOOT_SYSTEM) != 0) {
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index 735a5976672..2f8decf14f1 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -37,6 +37,10 @@ typedef enum OC_LEGACY_OS_TYPE_ {
   OcLegacyOsTypeIsoLinux
 } OC_LEGACY_OS_TYPE;
 
+typedef struct {
+  EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
+} LEGACY_ENTRY_CONTEXT;
+
 EFI_STATUS
 InternalGetBiosDiskNumber (
   IN      THUNK_CONTEXT             *ThunkContext,
@@ -58,7 +62,8 @@ InternalLoadAppleLegacyInterface (
 
 OC_LEGACY_OS_TYPE
 InternalGetPartitionLegacyOsType (
-  IN  EFI_HANDLE  PartitionHandle
+  IN EFI_HANDLE  PartitionHandle,
+  IN BOOLEAN     IsCdRomSupported
   );
 
 EFI_STATUS
diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index ad9638ec12e..5f49852c4ab 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -20,11 +20,12 @@ static CONST EFI_DEVICE_PATH_PROTOCOL  *AppleLegacyInterfaceMediaDevicePathPath
 
 #define MAX_APPLE_LEGACY_DEVICE_PATHS  16
 
-// STATIC
+STATIC
 BOOLEAN
 CheckLegacySignature (
-  IN CONST CHAR8         *SignatureStr,
-  IN MASTER_BOOT_RECORD  *Pbr
+  IN CONST CHAR8  *SignatureStr,
+  IN CONST UINT8  *Buffer,
+  IN CONST UINTN  BufferSize
   )
 {
   UINT32  Offset;
@@ -35,8 +36,8 @@ CheckLegacySignature (
            (CONST UINT8 *)SignatureStr,
            NULL,
            (CONST UINT32)AsciiStrLen (SignatureStr),
-           Pbr->BootStrapCode,
-           sizeof (Pbr->BootStrapCode),
+           Buffer,
+           BufferSize,
            &Offset
            );
 }
@@ -272,99 +273,82 @@ InternalLoadAppleLegacyInterface (
 
 OC_LEGACY_OS_TYPE
 InternalGetPartitionLegacyOsType (
-  IN  EFI_HANDLE  PartitionHandle
+  IN EFI_HANDLE  PartitionHandle,
+  IN BOOLEAN     IsCdRomSupported
   )
 {
-  EFI_STATUS          Status;
-  MASTER_BOOT_RECORD  *Mbr;
-  UINTN               MbrSize;
-  OC_LEGACY_OS_TYPE   LegacyOsType;
-
+  EFI_STATUS                Status;
+  UINT8                     *Buffer;
+  UINTN                     BufferSize;
+  MASTER_BOOT_RECORD        *Mbr;
   EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
-  OC_DISK_CONTEXT           DiskContext;
   EFI_HANDLE                DiskHandle;
+  OC_LEGACY_OS_TYPE         LegacyOsType;
 
   ASSERT (PartitionHandle != NULL);
 
-  //
-  // Read MBR of whole disk.
-  //
   DevicePath = DevicePathFromHandle (PartitionHandle);
   if (DevicePath == NULL) {
     return OcLegacyOsTypeNone;
   }
 
-  DebugPrintDevicePath (DEBUG_INFO, "OLB: Reading MBR for disk", DevicePath);
-
   DiskHandle = OcPartitionGetDiskHandle (DevicePath);
   if (DiskHandle == NULL) {
     return OcLegacyOsTypeNone;
   }
 
-  Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
-  if (Mbr == NULL) {
-    DEBUG ((DEBUG_INFO, "OLB: Disk does not contain a valid MBR partition table\n"));
-    return OcLegacyOsTypeNone;
-  }
-
   //
-  // For hard disk devices, get PBR sector instead.
+  // For CD devices, validate El-Torito structures.
+  // For hard disk and USB devices, validate MBR and PBR of target partition.
   //
-  if (!OcIsDiskCdRom (DevicePath)) {
-    FreePool (Mbr);
+  if (OcIsDiskCdRom (DevicePath)) {
+    if (!IsCdRomSupported) {
+      DEBUG ((DEBUG_INFO, "OLB: CD-ROM boot not supported on this platform\n"));
+      return OcLegacyOsTypeNone;
+    }
 
-    //
-    // Retrieve the first sector of the partition.
-    //
-    DebugPrintDevicePath (DEBUG_INFO, "OLB: Reading PBR for partition", DevicePath);
-    Status = OcDiskInitializeContext (
-               &DiskContext,
-               PartitionHandle,
-               TRUE
-               );
+    DebugPrintDevicePath (DEBUG_INFO, "OLB: Reading El-Torito for CDROM", DevicePath);
+    Status = OcDiskReadElTorito (DevicePath, &Buffer, &BufferSize);
     if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_INFO, "OLB: Failed reading El-Torito - %r\n", Status));
       return OcLegacyOsTypeNone;
     }
-
-    MbrSize = ALIGN_VALUE (sizeof (*Mbr), DiskContext.BlockSize);
-    Mbr     = (MASTER_BOOT_RECORD *)AllocatePool (MbrSize);
+  } else {
+    DebugPrintDevicePath (DEBUG_INFO, "OLB: Reading MBR for parent disk", DevicePath);
+    Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
     if (Mbr == NULL) {
-      DEBUG ((DEBUG_INFO, "OLB: Buffer allocation error\n"));
+      DEBUG ((DEBUG_INFO, "OLB: Disk does not contain a valid MBR\n"));
       return OcLegacyOsTypeNone;
     }
 
-    Status = OcDiskRead (
-               &DiskContext,
-               0,
-               MbrSize,
-               Mbr
-               );
-    if (EFI_ERROR (Status)) {
-      FreePool (Mbr);
+    FreePool (Mbr);
+
+    //
+    // Retrieve PBR for partition.
+    //
+    DebugPrintDevicePath (DEBUG_INFO, "OLB: Reading PBR for partition", DevicePath);
+    Mbr = OcGetDiskMbrTable (PartitionHandle, FALSE);
+    if (Mbr == NULL) {
+      DEBUG ((DEBUG_INFO, "OLB: Partition does not contain a valid PBR\n"));
       return OcLegacyOsTypeNone;
     }
-  }
 
-  DebugPrintHexDump (DEBUG_INFO, "OLB: MbrHEX", Mbr->BootStrapCode, sizeof (Mbr->BootStrapCode));
-
-  //
-  // Validate signature in MBR.
-  //
-  if (Mbr->Signature != MBR_SIGNATURE) {
-    FreePool (Mbr);
-    return OcLegacyOsTypeNone;
+    Buffer     = (UINT8 *)Mbr;
+    BufferSize = sizeof (*Mbr);
   }
 
+  DebugPrintHexDump (DEBUG_INFO, "OLB: PbrHEX", Buffer, BufferSize);
+
   //
   // Validate sector contents and check for known signatures
   // indicating the partition is bootable.
   //
-  if (CheckLegacySignature ("BOOTMGR", Mbr)) {
+  if (CheckLegacySignature ("BOOTMGR", Buffer, BufferSize)) {
     LegacyOsType = OcLegacyOsTypeWindowsBootmgr;
-  } else if (CheckLegacySignature ("NTLDR", Mbr)) {
+  } else if (CheckLegacySignature ("NTLDR", Buffer, BufferSize)) {
     LegacyOsType = OcLegacyOsTypeWindowsNtldr;
-  } else if (  CheckLegacySignature ("ISOLINUX", Mbr)
-            || CheckLegacySignature ("isolinux", Mbr))
+  } else if (  CheckLegacySignature ("ISOLINUX", Buffer, BufferSize)
+            || CheckLegacySignature ("isolinux", Buffer, BufferSize))
   {
     LegacyOsType = OcLegacyOsTypeIsoLinux;
   } else {
@@ -372,7 +356,7 @@ InternalGetPartitionLegacyOsType (
     DEBUG ((DEBUG_INFO, "OLB: Unknown legacy bootsector signature\n"));
   }
 
-  FreePool (Mbr);
+  FreePool (Buffer);
 
   return LegacyOsType;
 }
@@ -441,7 +425,7 @@ InternalLoadLegacyPbr (
 
   Mbr = OcGetDiskMbrTable (DiskHandle, TRUE);
   if (Mbr == NULL) {
-    DEBUG ((DEBUG_INFO, "OLB: Disk does not contain a valid MBR partition table\n"));
+    DEBUG ((DEBUG_INFO, "OLB: Disk does not contain a valid MBR\n"));
     FreePool (Pbr);
     return EFI_INVALID_PARAMETER;
   }
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index 8b07e685267..e5a7a838cc2 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -43,13 +43,17 @@ InternalFreePickerEntry (
 STATIC
 EFI_STATUS
 ExternalSystemActionDoLegacyBoot (
-  IN OUT          OC_PICKER_CONTEXT         *PickerContext,
-  IN              EFI_DEVICE_PATH_PROTOCOL  *DevicePath
+  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
+  IN              VOID               *ActionContext
   )
 {
   EFI_STATUS                 Status;
   EFI_HANDLE                 LoadedImageHandle;
   EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
+  LEGACY_ENTRY_CONTEXT       *LegacyContext;
+  CONST CHAR8                *Args;
+
+  LegacyContext = ActionContext;
 
   //
   // Load and start legacy OS.
@@ -57,11 +61,11 @@ ExternalSystemActionDoLegacyBoot (
   // On Macs, use the Apple legacy interface.
   // On other systems, use the Legacy8259 protocol.
   //
-  DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy device path", DevicePath);
+  DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy device path", LegacyContext->DevicePath);
   if (mIsAppleInterfaceSupported) {
     Status = InternalLoadAppleLegacyInterface (
                mImageHandle,
-               DevicePath,
+               LegacyContext->DevicePath,
                &LoadedImageHandle
                );
     if (EFI_ERROR (Status)) {
@@ -69,6 +73,9 @@ ExternalSystemActionDoLegacyBoot (
       return Status;
     }
 
+    //
+    // Specify boot device type on loaded image.
+    //
     Status = gBS->HandleProtocol (
                     LoadedImageHandle,
                     &gEfiLoadedImageProtocolGuid,
@@ -82,23 +89,21 @@ ExternalSystemActionDoLegacyBoot (
     LoadedImage->LoadOptionsSize = 0;
     LoadedImage->LoadOptions     = NULL;
 
-    CONST CHAR8  *Args;
-
-    Args = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
+    if (OcIsDiskCdRom (LegacyContext->DevicePath)) {
+      Args = AllocateCopyPool (L_STR_SIZE ("CD"), "CD");
+    } else {
+      Args = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
+    }
 
     OcAppendArgumentsToLoadedImage (LoadedImage, &Args, 1, TRUE);
-    DEBUG ((
-      DEBUG_INFO,
-      "OCB: Args <%s>\n",
-      LoadedImage->LoadOptions
-      ));
+
     Status = gBS->StartImage (LoadedImageHandle, NULL, NULL);
     if (EFI_ERROR (Status)) {
       DEBUG ((DEBUG_WARN, "OLB: Failure while starting Apple legacy interface - %r\n", Status));
       return Status;
     }
   } else {
-    InternalLoadLegacyPbr (DevicePath);
+    InternalLoadLegacyPbr (LegacyContext->DevicePath);
   }
 
   return EFI_SUCCESS;
@@ -114,84 +119,96 @@ OcGetLegacyBootEntries (
   OUT       UINTN                   *NumEntries
   )
 {
-  // EFI_STATUS                       Status;
-  // EFI_SIMPLE_FILE_SYSTEM_PROTOCOL  *FileSystem;
-  // EFI_FILE_PROTOCOL                *RootDirectory;
-  // UINT32                           FileSystemPolicy;
+  EFI_STATUS  Status;
+  UINTN       NoHandles;
+  EFI_HANDLE  *Handles;
+  UINTN       HandleIndex;
+
+  EFI_HANDLE                BlockDeviceHandle;
+  EFI_DEVICE_PATH_PROTOCOL  *BlockDevicePath;
+  OC_LEGACY_OS_TYPE         LegacyOsType;
+  OC_FLEX_ARRAY             *FlexPickerEntries;
+  OC_PICKER_ENTRY           *PickerEntry;
 
-  OC_LEGACY_OS_TYPE  LegacyType;
-  OC_PICKER_ENTRY    *PickerEntry;
+  ASSERT (PickerContext != NULL);
+  ASSERT (Entries     != NULL);
+  ASSERT (NumEntries  != NULL);
 
   //
-  // No custom entries.
+  // Custom entries only.
   //
-  if (Device == NULL) {
+  if (Device != NULL) {
     return EFI_NOT_FOUND;
   }
 
+  FlexPickerEntries = OcFlexArrayInit (sizeof (OC_PICKER_ENTRY), (OC_FLEX_ARRAY_FREE_ITEM)InternalFreePickerEntry);
+  if (FlexPickerEntries == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
   //
-  // Open partition file system.
+  // Get all Block I/O handles.
   //
+  Status = gBS->LocateHandleBuffer (
+                  ByProtocol,
+                  &gEfiBlockIoProtocolGuid,
+                  NULL,
+                  &NoHandles,
+                  &Handles
+                  );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_WARN, "OLB: Failed to get Block I/O handles - %r\n", Status));
+    OcFlexArrayFree (&FlexPickerEntries);
+    return Status;
+  }
 
-  /* Status = gBS->HandleProtocol (
-                   Device,
-                   &gEfiSimpleFileSystemProtocolGuid,
-                   (VOID **)&FileSystem
-                   );
-   if (EFI_ERROR (Status)) {
-     DEBUG ((DEBUG_WARN, "OLB: Missing filesystem - %r\n", Status));
-     return Status;
-   }
-
-   //
-   // Get handle to partiton root directory.
-   //
-   Status = FileSystem->OpenVolume (
-                          FileSystem,
-                          &RootDirectory
-                          );
-   if (EFI_ERROR (Status)) {
-     DEBUG ((DEBUG_WARN, "OLB: Invalid root volume - %r\n", Status));
-     return Status;
-   }
-
-   FileSystemPolicy = OcGetFileSystemPolicyType (Device);*/
+  for (HandleIndex = 0; HandleIndex < NoHandles; HandleIndex++) {
+    BlockDeviceHandle = Handles[HandleIndex];
 
-  //
-  // Disallow all but NTFS filesystems.
-  //
-  // if ((FileSystemPolicy & OC_SCAN_ALLOW_FS_NTFS) != 0) {
-  //   DEBUG ((DEBUG_INFO, "OLB: Not scanning non-NTFS filesystem\n"));
-  //  Status = EFI_NOT_FOUND;
-  // }
+    //
+    // Detect legacy OS type.
+    //
+    LegacyOsType = InternalGetPartitionLegacyOsType (BlockDeviceHandle, mIsAppleInterfaceSupported);
+    if (LegacyOsType == OcLegacyOsTypeNone) {
+      continue;
+    }
 
-  //
-  // Scan for boot entry (only one entry per filesystem).
-  //
-  LegacyType = InternalGetPartitionLegacyOsType (Device);
-  // RootDirectory->Close (RootDirectory);
-  if (LegacyType == OcLegacyOsTypeNone) {
-    return EFI_NOT_FOUND;
-  }
+    BlockDevicePath = DevicePathFromHandle (BlockDeviceHandle);
+    if (BlockDevicePath == NULL) {
+      DEBUG ((DEBUG_INFO, "OLB: Could not find Device Path for block device\n"));
+      continue;
+    }
+
+    //
+    // Create picker entry.
+    //
+    PickerEntry = OcFlexArrayAddItem (FlexPickerEntries);
+    if (PickerEntry == NULL) {
+      OcFlexArrayFree (&FlexPickerEntries);
+      return EFI_OUT_OF_RESOURCES;
+    }
+
+    CHAR16  *str2 = ConvertDevicePathToText (BlockDevicePath, FALSE, FALSE);
+    CHAR8   *str  = AllocateZeroPool (StrLen (str2) + 1);
 
-  CHAR16  *str2 = ConvertDevicePathToText (DevicePathFromHandle (Device), FALSE, FALSE);
-  CHAR8   *str  = AllocateZeroPool (StrLen (str2) + 1);
+    UnicodeStrToAsciiStrS (str2, str, StrLen (str2) + 1);
 
-  UnicodeStrToAsciiStrS (str2, str, StrLen (str2) + 1);
+    PickerEntry->Id                   = str;
+    PickerEntry->Name                 = "Windows (legacy)";
+    PickerEntry->Path                 = NULL;
+    PickerEntry->Arguments            = NULL;
+    PickerEntry->Flavour              = OC_FLAVOUR_WINDOWS;
+    PickerEntry->Tool                 = FALSE;
+    PickerEntry->TextMode             = TRUE;
+    PickerEntry->RealPath             = FALSE;
+    PickerEntry->ExternalSystemAction = ExternalSystemActionDoLegacyBoot;
 
-  PickerEntry                       = AllocateZeroPool (sizeof (*PickerEntry));
-  PickerEntry->Id                   = str;
-  PickerEntry->Name                 = "Windows (legacy)";
-  PickerEntry->Path                 = NULL;
-  PickerEntry->Arguments            = NULL;
-  PickerEntry->Flavour              = OC_FLAVOUR_WINDOWS;
-  PickerEntry->Tool                 = FALSE;
-  PickerEntry->TextMode             = TRUE;
-  PickerEntry->RealPath             = FALSE;
-  PickerEntry->ExternalSystemAction = ExternalSystemActionDoLegacyBoot;
+    LEGACY_ENTRY_CONTEXT  *LegacyContext = AllocateZeroPool (sizeof (LEGACY_ENTRY_CONTEXT));
+    LegacyContext->DevicePath                = BlockDevicePath;
+    PickerEntry->ExternalSystemActionContext = LegacyContext;
+  }
 
-  *Entries    = PickerEntry;
-  *NumEntries = 1;
+  OcFlexArrayFreeContainer (&FlexPickerEntries, (VOID **)Entries, NumEntries);
 
   return EFI_SUCCESS;
 }

From d3f5845bad964f9a05a560ecca8a19c1c3bbc43b Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 16:44:51 -0500
Subject: [PATCH 37/55] OcFileLib: Fix Windows builds

---
 Library/OcFileLib/DiskMisc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index 9008d8124b7..123abb76180 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -432,7 +432,7 @@ OcDiskReadElTorito (
   //
   // TODO: Unclear whether the sector size here is the native CD size 2048 or 512.
   //
-  BootBufferSize = CdNode->PartitionSize * DiskContext.BlockSize;
+  BootBufferSize = (UINTN)(CdNode->PartitionSize * DiskContext.BlockSize);
   BootBuffer     = AllocatePool (BootBufferSize);
   if (BootBuffer == NULL) {
     return EFI_OUT_OF_RESOURCES;

From 6335b3391413019c3f69e483444142cd190c3b39 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 17:24:09 -0500
Subject: [PATCH 38/55] OpenLegacyBoot: Cleanup picker entry creation

---
 .../Acidanthera/Library/OcBootManagementLib.h |   4 +
 .../OcBootManagementLib/BootEntryManagement.c |   1 +
 Platform/OpenLegacyBoot/OpenLegacyBoot.c      | 120 ++++++++++++++----
 3 files changed, 101 insertions(+), 24 deletions(-)

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index 33fb388be85..44df0a4c041 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -634,6 +634,10 @@ typedef struct {
   // External boot system action context. Boot Entry Protocol only. Optional.
   //
   VOID                              *ExternalSystemActionContext;
+  //
+  // Whether this entry should be labeled as external to the system. Boot Entry Protocol only. Optional.
+  //
+  BOOLEAN                           External;
 } OC_PICKER_ENTRY;
 
 /**
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index f9b7bda3d73..f23b6db0320 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -725,6 +725,7 @@ InternalAddBootEntryFromCustomEntry (
     BootEntry->ExternalSystemActionContext = CustomEntry->ExternalSystemActionContext;
     BootEntry->AudioBasePath               = CustomEntry->AudioBasePath;
     BootEntry->AudioBaseType               = CustomEntry->AudioBaseType;
+    BootEntry->IsExternal                  = CustomEntry->External;
   } else if (CustomEntry->SystemAction) {
     BootEntry->Type          = OC_BOOT_SYSTEM;
     BootEntry->SystemAction  = CustomEntry->SystemAction;
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index e5a7a838cc2..81c7ee39c29 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -12,8 +12,27 @@
 STATIC EFI_HANDLE  mImageHandle;
 STATIC BOOLEAN     mIsAppleInterfaceSupported;
 
+STATIC
+CHAR8 *
+GetLegacyEntryName (
+  OC_LEGACY_OS_TYPE  LegacyOsType
+  )
+{
+  return AllocateCopyPool (L_STR_SIZE ("Windows (legacy)"), "Windows (legacy)");
+}
+
+STATIC
+CHAR8 *
+GetLegacyEntryFlavour (
+  OC_LEGACY_OS_TYPE  LegacyOsType
+  )
+{
+  return AllocateCopyPool (L_STR_SIZE (OC_FLAVOUR_WINDOWS), OC_FLAVOUR_WINDOWS);
+}
+
+STATIC
 VOID
-InternalFreePickerEntry (
+FreePickerEntry (
   IN   OC_PICKER_ENTRY  *Entry
   )
 {
@@ -23,21 +42,21 @@ InternalFreePickerEntry (
     return;
   }
 
-  //
-  // TODO: Is this un-CONST casting okay?
-  // (Are they CONST because they are not supposed to be freed when used as before?)
-  //
   if (Entry->Id != NULL) {
     FreePool ((CHAR8 *)Entry->Id);
   }
 
-  /*if (Entry->Name != NULL) {
+  if (Entry->Name != NULL) {
     FreePool ((CHAR8 *)Entry->Name);
-  }*/
+  }
 
   if (Entry->Flavour != NULL) {
     FreePool ((CHAR8 *)Entry->Flavour);
   }
+
+  if (Entry->ExternalSystemActionContext != NULL) {
+    FreePool (Entry->ExternalSystemActionContext);
+  }
 }
 
 STATIC
@@ -123,12 +142,19 @@ OcGetLegacyBootEntries (
   UINTN       NoHandles;
   EFI_HANDLE  *Handles;
   UINTN       HandleIndex;
+  UINT32      ScanPolicy;
+  BOOLEAN     IsExternal;
+
+  CHAR16  *UnicodeDevicePath;
+  CHAR8   *AsciiDevicePath;
+  UINTN   AsciiDevicePathSize;
 
   EFI_HANDLE                BlockDeviceHandle;
   EFI_DEVICE_PATH_PROTOCOL  *BlockDevicePath;
   OC_LEGACY_OS_TYPE         LegacyOsType;
   OC_FLEX_ARRAY             *FlexPickerEntries;
   OC_PICKER_ENTRY           *PickerEntry;
+  LEGACY_ENTRY_CONTEXT      *LegacyContext;
 
   ASSERT (PickerContext != NULL);
   ASSERT (Entries     != NULL);
@@ -141,7 +167,7 @@ OcGetLegacyBootEntries (
     return EFI_NOT_FOUND;
   }
 
-  FlexPickerEntries = OcFlexArrayInit (sizeof (OC_PICKER_ENTRY), (OC_FLEX_ARRAY_FREE_ITEM)InternalFreePickerEntry);
+  FlexPickerEntries = OcFlexArrayInit (sizeof (OC_PICKER_ENTRY), (OC_FLEX_ARRAY_FREE_ITEM)FreePickerEntry);
   if (FlexPickerEntries == NULL) {
     return EFI_OUT_OF_RESOURCES;
   }
@@ -165,6 +191,17 @@ OcGetLegacyBootEntries (
   for (HandleIndex = 0; HandleIndex < NoHandles; HandleIndex++) {
     BlockDeviceHandle = Handles[HandleIndex];
 
+    //
+    // If device type locking is set and this device is not allowed,
+    // skip device.
+    //
+    if ((PickerContext->ScanPolicy & OC_SCAN_DEVICE_LOCK) != 0) {
+      ScanPolicy = OcGetDevicePolicyType (BlockDeviceHandle, &IsExternal);
+      if ((ScanPolicy & PickerContext->ScanPolicy) == 0) {
+        continue;
+      }
+    }
+
     //
     // Detect legacy OS type.
     //
@@ -180,7 +217,7 @@ OcGetLegacyBootEntries (
     }
 
     //
-    // Create picker entry.
+    // Create and add picker entry to entries.
     //
     PickerEntry = OcFlexArrayAddItem (FlexPickerEntries);
     if (PickerEntry == NULL) {
@@ -188,24 +225,59 @@ OcGetLegacyBootEntries (
       return EFI_OUT_OF_RESOURCES;
     }
 
-    CHAR16  *str2 = ConvertDevicePathToText (BlockDevicePath, FALSE, FALSE);
-    CHAR8   *str  = AllocateZeroPool (StrLen (str2) + 1);
+    //
+    // Device Path will be used as ID and is required for default entry matching.
+    //
+    UnicodeDevicePath = ConvertDevicePathToText (BlockDevicePath, FALSE, FALSE);
+    if (UnicodeDevicePath == NULL) {
+      OcFlexArrayFree (&FlexPickerEntries);
+      return EFI_OUT_OF_RESOURCES;
+    }
+
+    AsciiDevicePathSize = (StrLen (UnicodeDevicePath) + 1) * sizeof (CHAR8);
+    AsciiDevicePath     = AllocatePool (AsciiDevicePathSize);
+    if (AsciiDevicePath == NULL) {
+      FreePool (UnicodeDevicePath);
+      OcFlexArrayFree (&FlexPickerEntries);
+      return EFI_OUT_OF_RESOURCES;
+    }
+
+    Status = UnicodeStrToAsciiStrS (UnicodeDevicePath, AsciiDevicePath, AsciiDevicePathSize);
+    FreePool (UnicodeDevicePath);
+    if (EFI_ERROR (Status)) {
+      FreePool (AsciiDevicePath);
+      OcFlexArrayFree (&FlexPickerEntries);
+      return Status;
+    }
 
-    UnicodeStrToAsciiStrS (str2, str, StrLen (str2) + 1);
+    //
+    // Context referencing booted entry later on.
+    //
+    LegacyContext = AllocateZeroPool (sizeof (*LegacyContext));
+    if (LegacyContext == NULL) {
+      FreePool (AsciiDevicePath);
+      OcFlexArrayFree (&FlexPickerEntries);
+      return EFI_OUT_OF_RESOURCES;
+    }
 
-    PickerEntry->Id                   = str;
-    PickerEntry->Name                 = "Windows (legacy)";
-    PickerEntry->Path                 = NULL;
-    PickerEntry->Arguments            = NULL;
-    PickerEntry->Flavour              = OC_FLAVOUR_WINDOWS;
-    PickerEntry->Tool                 = FALSE;
-    PickerEntry->TextMode             = TRUE;
-    PickerEntry->RealPath             = FALSE;
-    PickerEntry->ExternalSystemAction = ExternalSystemActionDoLegacyBoot;
+    LegacyContext->DevicePath = BlockDevicePath;
 
-    LEGACY_ENTRY_CONTEXT  *LegacyContext = AllocateZeroPool (sizeof (LEGACY_ENTRY_CONTEXT));
-    LegacyContext->DevicePath                = BlockDevicePath;
+    PickerEntry->Id        = AsciiDevicePath;
+    PickerEntry->Name      = GetLegacyEntryName (LegacyOsType);
+    PickerEntry->Path      = NULL;
+    PickerEntry->Arguments = NULL;
+    PickerEntry->Flavour   = GetLegacyEntryFlavour (LegacyOsType);
+    PickerEntry->Tool      = FALSE;
+    PickerEntry->TextMode  = FALSE;
+    PickerEntry->RealPath  = FALSE;
+
+    PickerEntry->ExternalSystemAction        = ExternalSystemActionDoLegacyBoot;
     PickerEntry->ExternalSystemActionContext = LegacyContext;
+
+    if ((PickerEntry->Name == NULL) || (PickerEntry->Flavour == NULL)) {
+      OcFlexArrayFree (&FlexPickerEntries);
+      return EFI_OUT_OF_RESOURCES;
+    }
   }
 
   OcFlexArrayFreeContainer (&FlexPickerEntries, (VOID **)Entries, NumEntries);
@@ -230,7 +302,7 @@ OcFreeLegacyBootEntries (
   }
 
   for (Index = 0; Index < NumEntries; Index++) {
-    InternalFreePickerEntry (&(*Entries)[Index]);
+    FreePickerEntry (&(*Entries)[Index]);
   }
 
   FreePool (*Entries);

From 52d1fe943c22fa8455bc2906d02bd96dcef6868e Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 17:30:49 -0500
Subject: [PATCH 39/55] OpenLegacyBoot: Fix Windows builds

---
 Platform/OpenLegacyBoot/LegacyBootSupport.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index 5f49852c4ab..6195fd70687 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -24,8 +24,8 @@ STATIC
 BOOLEAN
 CheckLegacySignature (
   IN CONST CHAR8  *SignatureStr,
-  IN CONST UINT8  *Buffer,
-  IN CONST UINTN  BufferSize
+  IN       UINT8  *Buffer,
+  IN       UINTN  BufferSize
   )
 {
   UINT32  Offset;
@@ -37,7 +37,7 @@ CheckLegacySignature (
            NULL,
            (CONST UINT32)AsciiStrLen (SignatureStr),
            Buffer,
-           BufferSize,
+           (UINT32)BufferSize,
            &Offset
            );
 }

From 86b0f06467a11bdffadf453e6b7556245fbc28bb Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 18:53:52 -0500
Subject: [PATCH 40/55] OpenLegacyBoot: Fix external device handling

---
 Platform/OpenLegacyBoot/BiosDisk.c           |  6 +--
 Platform/OpenLegacyBoot/LegacyBootInternal.h |  1 +
 Platform/OpenLegacyBoot/OpenLegacyBoot.c     | 41 +++++++++++++-------
 3 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/Platform/OpenLegacyBoot/BiosDisk.c b/Platform/OpenLegacyBoot/BiosDisk.c
index 4fa45a5045e..e9ee71dd8a2 100644
--- a/Platform/OpenLegacyBoot/BiosDisk.c
+++ b/Platform/OpenLegacyBoot/BiosDisk.c
@@ -57,13 +57,13 @@ BiosDiskReset (
   CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
 
   if (CarryFlag != 0) {
-    DEBUG ((DEBUG_WARN, "OLB: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AL));
+    DEBUG ((DEBUG_INFO, "OLB: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AL));
     if (Regs.H.AL == BIOS_RESET_FAILED) {
       Regs.H.AH = 0x00;
       Regs.H.DL = DriveNumber;
       CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
       if (CarryFlag != 0) {
-        DEBUG ((DEBUG_WARN, "OLB: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AH));
+        DEBUG ((DEBUG_INFO, "OLB: Failed to reset BIOS disk %u, error 0x%X\n", DriveNumber, Regs.H.AH));
         return EFI_DEVICE_ERROR;
       }
     }
@@ -156,7 +156,7 @@ InternalGetBiosDiskNumber (
                                       &DeviceAddressPacketAddress
                                       );
   if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_WARN, "OLB: Failure allocating low memory packet for BIOS disk read - %r\n", Status));
+    DEBUG ((DEBUG_INFO, "OLB: Failure allocating low memory packet for BIOS disk read - %r\n", Status));
     return Status;
   }
 
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index 2f8decf14f1..d6d276101d5 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -39,6 +39,7 @@ typedef enum OC_LEGACY_OS_TYPE_ {
 
 typedef struct {
   EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
+  BOOLEAN                     IsExternal;
 } LEGACY_ENTRY_CONTEXT;
 
 EFI_STATUS
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index 81c7ee39c29..da4542e509c 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -70,7 +70,7 @@ ExternalSystemActionDoLegacyBoot (
   EFI_HANDLE                 LoadedImageHandle;
   EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
   LEGACY_ENTRY_CONTEXT       *LegacyContext;
-  CONST CHAR8                *Args;
+  CONST CHAR8                *AppleBootArg;
 
   LegacyContext = ActionContext;
 
@@ -88,12 +88,12 @@ ExternalSystemActionDoLegacyBoot (
                &LoadedImageHandle
                );
     if (EFI_ERROR (Status)) {
-      DEBUG ((DEBUG_WARN, "OLB: Failure while loading Apple legacy interface - %r\n", Status));
+      DEBUG ((DEBUG_INFO, "OLB: Failure while loading Apple legacy interface - %r\n", Status));
       return Status;
     }
 
     //
-    // Specify boot device type on loaded image.
+    // Specify boot device type argument on loaded image.
     //
     Status = gBS->HandleProtocol (
                     LoadedImageHandle,
@@ -101,7 +101,8 @@ ExternalSystemActionDoLegacyBoot (
                     (VOID **)&LoadedImage
                     );
     if (EFI_ERROR (Status)) {
-      DEBUG ((DEBUG_WARN, "OLB: Failure while loading Apple legacy interface - %r\n", Status));
+      DEBUG ((DEBUG_INFO, "OLB: Failure while loading Apple legacy interface - %r\n", Status));
+      gBS->UnloadImage (LoadedImageHandle);
       return Status;
     }
 
@@ -109,20 +110,30 @@ ExternalSystemActionDoLegacyBoot (
     LoadedImage->LoadOptions     = NULL;
 
     if (OcIsDiskCdRom (LegacyContext->DevicePath)) {
-      Args = AllocateCopyPool (L_STR_SIZE ("CD"), "CD");
+      AppleBootArg = "CD";
+    } else if (LegacyContext->IsExternal) {
+      AppleBootArg = "USB";
     } else {
-      Args = AllocateCopyPool (L_STR_SIZE ("HD"), "HD");
+      AppleBootArg = "HD";
     }
 
-    OcAppendArgumentsToLoadedImage (LoadedImage, &Args, 1, TRUE);
+    if (!OcAppendArgumentsToLoadedImage (LoadedImage, &AppleBootArg, 1, TRUE)) {
+      gBS->UnloadImage (LoadedImageHandle);
+      return EFI_INVALID_PARAMETER;
+    }
 
     Status = gBS->StartImage (LoadedImageHandle, NULL, NULL);
     if (EFI_ERROR (Status)) {
-      DEBUG ((DEBUG_WARN, "OLB: Failure while starting Apple legacy interface - %r\n", Status));
+      DEBUG ((DEBUG_INFO, "OLB: Failure while starting Apple legacy interface - %r\n", Status));
+      gBS->UnloadImage (LoadedImageHandle);
       return Status;
     }
   } else {
-    InternalLoadLegacyPbr (LegacyContext->DevicePath);
+    Status = InternalLoadLegacyPbr (LegacyContext->DevicePath);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_INFO, "OLB: Failure while starting legacy PBR interface - %r\n", Status));
+      return Status;
+    }
   }
 
   return EFI_SUCCESS;
@@ -183,7 +194,7 @@ OcGetLegacyBootEntries (
                   &Handles
                   );
   if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_WARN, "OLB: Failed to get Block I/O handles - %r\n", Status));
+    DEBUG ((DEBUG_INFO, "OLB: Failed to get Block I/O handles - %r\n", Status));
     OcFlexArrayFree (&FlexPickerEntries);
     return Status;
   }
@@ -195,11 +206,9 @@ OcGetLegacyBootEntries (
     // If device type locking is set and this device is not allowed,
     // skip device.
     //
-    if ((PickerContext->ScanPolicy & OC_SCAN_DEVICE_LOCK) != 0) {
-      ScanPolicy = OcGetDevicePolicyType (BlockDeviceHandle, &IsExternal);
-      if ((ScanPolicy & PickerContext->ScanPolicy) == 0) {
-        continue;
-      }
+    ScanPolicy = OcGetDevicePolicyType (BlockDeviceHandle, &IsExternal);
+    if (((PickerContext->ScanPolicy & OC_SCAN_DEVICE_LOCK) != 0) && ((ScanPolicy & PickerContext->ScanPolicy) == 0)) {
+      continue;
     }
 
     //
@@ -261,6 +270,7 @@ OcGetLegacyBootEntries (
     }
 
     LegacyContext->DevicePath = BlockDevicePath;
+    LegacyContext->IsExternal = IsExternal;
 
     PickerEntry->Id        = AsciiDevicePath;
     PickerEntry->Name      = GetLegacyEntryName (LegacyOsType);
@@ -270,6 +280,7 @@ OcGetLegacyBootEntries (
     PickerEntry->Tool      = FALSE;
     PickerEntry->TextMode  = FALSE;
     PickerEntry->RealPath  = FALSE;
+    PickerEntry->External  = IsExternal;
 
     PickerEntry->ExternalSystemAction        = ExternalSystemActionDoLegacyBoot;
     PickerEntry->ExternalSystemActionContext = LegacyContext;

From 12085032fcc8316dff2bc49cf96c1c05fd0dcf7b Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 19:40:16 -0500
Subject: [PATCH 41/55] OpenLegacyBoot: Fix device path storage on legacy
 entries

---
 .../Acidanthera/Library/OcBootManagementLib.h | 12 +--
 .../OcBootManagementLib/BootEntryManagement.c | 14 ++--
 Platform/OpenLegacyBoot/LegacyBootInternal.h  |  5 --
 Platform/OpenLegacyBoot/OpenLegacyBoot.c      | 78 ++++++++-----------
 4 files changed, 45 insertions(+), 64 deletions(-)

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index 44df0a4c041..bd15da754f7 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -200,8 +200,8 @@ EFI_STATUS
 typedef
 EFI_STATUS
 (*OC_BOOT_EXTERNAL_SYSTEM_ACTION) (
-  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
-  IN              VOID               *ActionContext
+  IN OUT  OC_PICKER_CONTEXT         *PickerContext,
+  IN      EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   );
 
 /**
@@ -227,10 +227,6 @@ typedef struct OC_BOOT_ENTRY_ {
   //
   OC_BOOT_EXTERNAL_SYSTEM_ACTION    ExternalSystemAction;
   //
-  // Action to perform on execution. Only valid for external boot system entries.
-  //
-  VOID                              *ExternalSystemActionContext;
-  //
   // Id under which to save entry as default.
   //
   CHAR16                            *Id;
@@ -631,9 +627,9 @@ typedef struct {
   //
   OC_BOOT_EXTERNAL_SYSTEM_ACTION    ExternalSystemAction;
   //
-  // External boot system action context. Boot Entry Protocol only. Optional.
+  // External boot system Device Path. Boot Entry Protocol only. Optional.
   //
-  VOID                              *ExternalSystemActionContext;
+  EFI_DEVICE_PATH_PROTOCOL          *ExternalSystemDevicePath;
   //
   // Whether this entry should be labeled as external to the system. Boot Entry Protocol only. Optional.
   //
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index f23b6db0320..6486f4c6e0a 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -720,12 +720,12 @@ InternalAddBootEntryFromCustomEntry (
     ));
 
   if (CustomEntry->ExternalSystemAction) {
-    BootEntry->Type                        = OC_BOOT_EXTERNAL_SYSTEM;
-    BootEntry->ExternalSystemAction        = CustomEntry->ExternalSystemAction;
-    BootEntry->ExternalSystemActionContext = CustomEntry->ExternalSystemActionContext;
-    BootEntry->AudioBasePath               = CustomEntry->AudioBasePath;
-    BootEntry->AudioBaseType               = CustomEntry->AudioBaseType;
-    BootEntry->IsExternal                  = CustomEntry->External;
+    BootEntry->Type                 = OC_BOOT_EXTERNAL_SYSTEM;
+    BootEntry->ExternalSystemAction = CustomEntry->ExternalSystemAction;
+    BootEntry->AudioBasePath        = CustomEntry->AudioBasePath;
+    BootEntry->AudioBaseType        = CustomEntry->AudioBaseType;
+    BootEntry->DevicePath           = CustomEntry->ExternalSystemDevicePath;
+    BootEntry->IsExternal           = CustomEntry->External;
   } else if (CustomEntry->SystemAction) {
     BootEntry->Type          = OC_BOOT_SYSTEM;
     BootEntry->SystemAction  = CustomEntry->SystemAction;
@@ -2512,7 +2512,7 @@ OcLoadBootEntry (
 
   if ((BootEntry->Type & OC_BOOT_EXTERNAL_SYSTEM) != 0) {
     ASSERT (BootEntry->ExternalSystemAction != NULL);
-    return BootEntry->ExternalSystemAction (Context, BootEntry->ExternalSystemActionContext);
+    return BootEntry->ExternalSystemAction (Context, BootEntry->DevicePath);
   }
 
   if ((BootEntry->Type & OC_BOOT_SYSTEM) != 0) {
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index d6d276101d5..ead42d71326 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -37,11 +37,6 @@ typedef enum OC_LEGACY_OS_TYPE_ {
   OcLegacyOsTypeIsoLinux
 } OC_LEGACY_OS_TYPE;
 
-typedef struct {
-  EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
-  BOOLEAN                     IsExternal;
-} LEGACY_ENTRY_CONTEXT;
-
 EFI_STATUS
 InternalGetBiosDiskNumber (
   IN      THUNK_CONTEXT             *ThunkContext,
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index da4542e509c..49bbef4c99c 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -53,38 +53,38 @@ FreePickerEntry (
   if (Entry->Flavour != NULL) {
     FreePool ((CHAR8 *)Entry->Flavour);
   }
-
-  if (Entry->ExternalSystemActionContext != NULL) {
-    FreePool (Entry->ExternalSystemActionContext);
-  }
 }
 
 STATIC
 EFI_STATUS
 ExternalSystemActionDoLegacyBoot (
-  IN OUT          OC_PICKER_CONTEXT  *PickerContext,
-  IN              VOID               *ActionContext
+  IN OUT  OC_PICKER_CONTEXT         *PickerContext,
+  IN      EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   )
 {
   EFI_STATUS                 Status;
+  EFI_HANDLE                 DiskHandle;
   EFI_HANDLE                 LoadedImageHandle;
   EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
-  LEGACY_ENTRY_CONTEXT       *LegacyContext;
+  BOOLEAN                    IsExternal;
   CONST CHAR8                *AppleBootArg;
 
-  LegacyContext = ActionContext;
-
   //
   // Load and start legacy OS.
   //
   // On Macs, use the Apple legacy interface.
   // On other systems, use the Legacy8259 protocol.
   //
-  DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy device path", LegacyContext->DevicePath);
+  DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy device path", DevicePath);
   if (mIsAppleInterfaceSupported) {
+    DiskHandle = OcPartitionGetPartitionHandle (DevicePath);
+    if (DiskHandle == NULL) {
+      return EFI_INVALID_PARAMETER;
+    }
+
     Status = InternalLoadAppleLegacyInterface (
                mImageHandle,
-               LegacyContext->DevicePath,
+               DevicePath,
                &LoadedImageHandle
                );
     if (EFI_ERROR (Status)) {
@@ -109,18 +109,23 @@ ExternalSystemActionDoLegacyBoot (
     LoadedImage->LoadOptionsSize = 0;
     LoadedImage->LoadOptions     = NULL;
 
-    if (OcIsDiskCdRom (LegacyContext->DevicePath)) {
+    OcGetDevicePolicyType (DiskHandle, &IsExternal);
+
+    if (OcIsDiskCdRom (DevicePath)) {
       AppleBootArg = "CD";
-    } else if (LegacyContext->IsExternal) {
+    } else if (IsExternal) {
       AppleBootArg = "USB";
     } else {
       AppleBootArg = "HD";
     }
 
-    if (!OcAppendArgumentsToLoadedImage (LoadedImage, &AppleBootArg, 1, TRUE)) {
-      gBS->UnloadImage (LoadedImageHandle);
-      return EFI_INVALID_PARAMETER;
-    }
+    OcAppendArgumentsToLoadedImage (
+      LoadedImage,
+      &AppleBootArg,
+      1,
+      TRUE
+      );
+    DEBUG ((DEBUG_INFO, "OLB: Apple legacy interface args <%s>\n", LoadedImage->LoadOptions));
 
     Status = gBS->StartImage (LoadedImageHandle, NULL, NULL);
     if (EFI_ERROR (Status)) {
@@ -129,7 +134,7 @@ ExternalSystemActionDoLegacyBoot (
       return Status;
     }
   } else {
-    Status = InternalLoadLegacyPbr (LegacyContext->DevicePath);
+    Status = InternalLoadLegacyPbr (DevicePath);
     if (EFI_ERROR (Status)) {
       DEBUG ((DEBUG_INFO, "OLB: Failure while starting legacy PBR interface - %r\n", Status));
       return Status;
@@ -165,7 +170,6 @@ OcGetLegacyBootEntries (
   OC_LEGACY_OS_TYPE         LegacyOsType;
   OC_FLEX_ARRAY             *FlexPickerEntries;
   OC_PICKER_ENTRY           *PickerEntry;
-  LEGACY_ENTRY_CONTEXT      *LegacyContext;
 
   ASSERT (PickerContext != NULL);
   ASSERT (Entries     != NULL);
@@ -259,31 +263,17 @@ OcGetLegacyBootEntries (
       return Status;
     }
 
-    //
-    // Context referencing booted entry later on.
-    //
-    LegacyContext = AllocateZeroPool (sizeof (*LegacyContext));
-    if (LegacyContext == NULL) {
-      FreePool (AsciiDevicePath);
-      OcFlexArrayFree (&FlexPickerEntries);
-      return EFI_OUT_OF_RESOURCES;
-    }
-
-    LegacyContext->DevicePath = BlockDevicePath;
-    LegacyContext->IsExternal = IsExternal;
-
-    PickerEntry->Id        = AsciiDevicePath;
-    PickerEntry->Name      = GetLegacyEntryName (LegacyOsType);
-    PickerEntry->Path      = NULL;
-    PickerEntry->Arguments = NULL;
-    PickerEntry->Flavour   = GetLegacyEntryFlavour (LegacyOsType);
-    PickerEntry->Tool      = FALSE;
-    PickerEntry->TextMode  = FALSE;
-    PickerEntry->RealPath  = FALSE;
-    PickerEntry->External  = IsExternal;
-
-    PickerEntry->ExternalSystemAction        = ExternalSystemActionDoLegacyBoot;
-    PickerEntry->ExternalSystemActionContext = LegacyContext;
+    PickerEntry->Id                       = AsciiDevicePath;
+    PickerEntry->Name                     = GetLegacyEntryName (LegacyOsType);
+    PickerEntry->Path                     = NULL;
+    PickerEntry->Arguments                = NULL;
+    PickerEntry->Flavour                  = GetLegacyEntryFlavour (LegacyOsType);
+    PickerEntry->Tool                     = FALSE;
+    PickerEntry->TextMode                 = FALSE;
+    PickerEntry->RealPath                 = FALSE;
+    PickerEntry->External                 = IsExternal;
+    PickerEntry->ExternalSystemAction     = ExternalSystemActionDoLegacyBoot;
+    PickerEntry->ExternalSystemDevicePath = BlockDevicePath;
 
     if ((PickerEntry->Name == NULL) || (PickerEntry->Flavour == NULL)) {
       OcFlexArrayFree (&FlexPickerEntries);

From dabc04a64c29ef2f48edd9e5c1718bbbb9e08627 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 21:23:20 -0500
Subject: [PATCH 42/55] OcBootManagementLib: Fix Apple legacy interface default
 entry handling

---
 .../OcBootManagementLib/BootEntryManagement.c | 66 +++++++++----------
 .../OcBootManagementLib/BootEntryProtocol.c   |  8 ---
 Library/OcFileLib/DiskMisc.c                  |  4 +-
 3 files changed, 32 insertions(+), 46 deletions(-)

diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 6486f4c6e0a..5bbf9103848 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -1327,7 +1327,7 @@ AddBootEntryFromBootOption (
     }
 
     //
-    // Attempt to handle detected legacy OS.
+    // Attempt to handle detected legacy OS via Apple legacy interface.
     //
     RemainingDevicePath = DevicePath;
     DevicePath          = OcDiskFindActiveMbrPartitionPath (
@@ -1340,34 +1340,30 @@ AddBootEntryFromBootOption (
     // Disk with MBR or hybrid MBR was detected.
     //
     if (DevicePath != NULL) {
-      //
-      // Ensure that we are allowed to boot from this filesystem.
-      //
-      FileSystem = InternalFileSystemForHandle (BootContext, FileSystemHandle, TRUE, NULL);
-      if (FileSystem != NULL) {
-        TextDevicePath = ConvertDevicePathToText (DevicePath, FALSE, FALSE);
-        if (TextDevicePath != NULL) {
-          //
-          // Add entry from externally provided legacy interface.
-          //
-          Status = OcAddEntriesFromBootEntryProtocol (
-                     BootContext,
-                     FileSystem,
-                     EntryProtocolHandles,
-                     EntryProtocolHandleCount,
-                     TextDevicePath,
-                     TRUE,
-                     FALSE
-                     );
-          if (!EFI_ERROR (Status)) {
-            if (EntryProtocolId != NULL) {
-              *EntryProtocolId = TextDevicePath;
-            }
-
-            IsAppleLegacyHandled = TRUE;
-          } else {
-            FreePool (TextDevicePath);
+      TextDevicePath = ConvertDevicePathToText (DevicePath, FALSE, FALSE);
+      if (TextDevicePath != NULL) {
+        //
+        // Add entry from externally provided legacy interface.
+        // Boot entry ID must be active partition Device Path.
+        //
+        Status = OcAddEntriesFromBootEntryProtocol (
+                   BootContext,
+                   CustomFileSystem,
+                   EntryProtocolHandles,
+                   EntryProtocolHandleCount,
+                   TextDevicePath,
+                   TRUE,
+                   FALSE
+                   );
+        if (!EFI_ERROR (Status)) {
+          if (EntryProtocolId != NULL) {
+            *EntryProtocolId = TextDevicePath;
           }
+
+          FileSystem           = CustomFileSystem;
+          IsAppleLegacyHandled = TRUE;
+        } else {
+          FreePool (TextDevicePath);
         }
       }
     }
@@ -2156,8 +2152,6 @@ OcScanForBootEntries (
                                            )
                                          );
 
-    IsDefaultEntryProtocolPartition = (DefaultEntryId != NULL);
-
     //
     // No entries, or only entry pre-created from boot entry protocol,
     // so process this directory with Apple Bless.
@@ -2195,11 +2189,6 @@ OcScanForBootEntries (
     AddBootEntryFromSelfRecovery (BootContext, FileSystem);
   }
 
-  if (DefaultEntryId != NULL) {
-    FreePool (DefaultEntryId);
-    DefaultEntryId = NULL;
-  }
-
   if (CustomFileSystem != NULL) {
     //
     // Insert the custom file system last for entry order.
@@ -2220,12 +2209,17 @@ OcScanForBootEntries (
       CustomFileSystem,
       EntryProtocolHandles,
       EntryProtocolHandleCount,
-      NULL,
+      DefaultEntryId,
       FALSE,
       FALSE
       );
   }
 
+  if (DefaultEntryId != NULL) {
+    FreePool (DefaultEntryId);
+    DefaultEntryId = NULL;
+  }
+
   OcFreeBootEntryProtocolHandles (&EntryProtocolHandles);
 
   if (BootContext->BootEntryCount == 0) {
diff --git a/Library/OcBootManagementLib/BootEntryProtocol.c b/Library/OcBootManagementLib/BootEntryProtocol.c
index 724fd8ccdfc..6bcde243c36 100644
--- a/Library/OcBootManagementLib/BootEntryProtocol.c
+++ b/Library/OcBootManagementLib/BootEntryProtocol.c
@@ -250,14 +250,6 @@ OcAddEntriesFromBootEntryProtocol (
 
   ASSERT (!CreateDefault || (DefaultEntryId != NULL));
 
-  //
-  // Non-filesystem entries cannot be saved as normal default boot option,
-  // but can be triggered as default boot item by boot entry protocol hotkey.
-  //
-  if (!CreateForHotKey && CreateDefault && (FileSystem->Handle == OC_CUSTOM_FS_HANDLE)) {
-    return EFI_NOT_FOUND;
-  }
-
   AddEntriesContext.ReturnStatus    = EFI_NOT_FOUND;
   AddEntriesContext.BootContext     = BootContext;
   AddEntriesContext.FileSystem      = FileSystem;
diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index 123abb76180..0c4eb67c75d 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -1089,13 +1089,13 @@ OcDiskFindActiveMbrPartitionPath (
 
   Status = gBS->LocateHandleBuffer (
                   ByProtocol,
-                  &gEfiSimpleFileSystemProtocolGuid,
+                  &gEfiBlockIoProtocolGuid,
                   NULL,
                   &NoHandles,
                   &Handles
                   );
   if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_INFO, "OCPI: Failed to locate FS handles\n"));
+    DEBUG ((DEBUG_INFO, "OCPI: Failed to locate Block I/O handles\n"));
     return NULL;
   }
 

From 9a710567407ec531ce653f250664a8cea24c709f Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 22:18:27 -0500
Subject: [PATCH 43/55] OcBootManagementLib: Fix device path use after free

---
 Library/OcBootManagementLib/BootEntryManagement.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 5bbf9103848..6b2c8a085ba 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -724,8 +724,13 @@ InternalAddBootEntryFromCustomEntry (
     BootEntry->ExternalSystemAction = CustomEntry->ExternalSystemAction;
     BootEntry->AudioBasePath        = CustomEntry->AudioBasePath;
     BootEntry->AudioBaseType        = CustomEntry->AudioBaseType;
-    BootEntry->DevicePath           = CustomEntry->ExternalSystemDevicePath;
     BootEntry->IsExternal           = CustomEntry->External;
+    BootEntry->DevicePath           = DuplicateDevicePath (CustomEntry->ExternalSystemDevicePath);
+
+    if (BootEntry->DevicePath == NULL) {
+      FreeBootEntry (BootEntry);
+      return EFI_OUT_OF_RESOURCES;
+    }
   } else if (CustomEntry->SystemAction) {
     BootEntry->Type          = OC_BOOT_SYSTEM;
     BootEntry->SystemAction  = CustomEntry->SystemAction;

From 5b9861b3a8efd4e7ae7dadc45ee08a347867fb33 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 19 Aug 2023 22:19:20 -0500
Subject: [PATCH 44/55] OpenLegacyBoot: Detect BIOS disk address for PC boot

---
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c  |  12 ++-
 Platform/OpenLegacyBoot/BiosDisk.c           | 100 ++++++++++++++++---
 Platform/OpenLegacyBoot/LegacyBootInternal.h |   9 +-
 Platform/OpenLegacyBoot/LegacyBootSupport.c  |  22 ++--
 4 files changed, 113 insertions(+), 30 deletions(-)

diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index bdacfa3e1dc..d69d19fd3b4 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -339,9 +339,8 @@ OcLegacyThunkFarCall86 (
   UINT16             *Stack16;
   IA32_REGISTER_SET  ThunkRegSet;
   BOOLEAN            Ret;
-  // BOOLEAN               InterruptState;
-  UINT64   TimerPeriod;
-  BOOLEAN  Enabled;
+  UINT64             TimerPeriod;
+  BOOLEAN            Enabled;
 
   EFI_TIMER_ARCH_PROTOCOL  *TimerProtocol;
 
@@ -405,8 +404,8 @@ OcLegacyThunkFarCall86 (
   ASSERT_EFI_ERROR (Status);
 
   //
-  // Clear the error flag; thunk code may set it. Stack16 should be the high address
-  // Make Statk16 address the low 16 bit must be not zero.
+  // Clear the error flag; thunk code may set it. Stack16 should be the high address.
+  // Make Stack16 address the low 16 bit must be not zero.
   //
   Stack16 = (UINT16 *)((UINT8 *)ThunkContext->RealModeBuffer + ThunkContext->RealModeBufferSize - sizeof (UINT16));
 
@@ -426,6 +425,9 @@ OcLegacyThunkFarCall86 (
   ThunkContext->RealModeState = &ThunkRegSet;
   AsmThunk16 (ThunkContext);
 
+  //
+  // EFI is likely trashed if we get here, but attempt to restore state.
+  //
   if ((Stack != NULL) && (StackSize != 0)) {
     //
     // Copy low memory stack to Stack
diff --git a/Platform/OpenLegacyBoot/BiosDisk.c b/Platform/OpenLegacyBoot/BiosDisk.c
index e9ee71dd8a2..c802de7200f 100644
--- a/Platform/OpenLegacyBoot/BiosDisk.c
+++ b/Platform/OpenLegacyBoot/BiosDisk.c
@@ -39,6 +39,8 @@ typedef struct {
   UINT64    Lba;
 } DEVICE_ADDRESS_PACKET;
 
+#define BIOS_DISK_CHECK_BUFFER_SECTOR_COUNT  4
+
 STATIC
 EFI_STATUS
 BiosDiskReset (
@@ -127,47 +129,93 @@ BiosDiskReadExtSectors (
   Regs.E.DS = EFI_SEGMENT (DeviceAddressPacket);
   CarryFlag = OcLegacyThunkBiosInt86 (ThunkContext, Legacy8259, 0x13, &Regs);
 
-  DEBUG ((DEBUG_INFO, "carry %u\n", CarryFlag));
+  if (CarryFlag != 0) {
+    return EFI_DEVICE_ERROR;
+  }
 
   return EFI_SUCCESS;
 }
 
 EFI_STATUS
-InternalGetBiosDiskNumber (
-  IN      THUNK_CONTEXT             *ThunkContext,
-  IN      EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
-  OUT  UINT8                        *DriveNumber
+InternalGetBiosDiskAddress (
+  IN  THUNK_CONTEXT             *ThunkContext,
+  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN  EFI_HANDLE                DiskHandle,
+  OUT UINT8                     *DriveAddress
   )
 {
   EFI_STATUS             Status;
+  OC_DISK_CONTEXT        DiskContext;
   UINT8                  DriveAddr;
   EFI_PHYSICAL_ADDRESS   DeviceAddressPacketAddress;
   DEVICE_ADDRESS_PACKET  *DeviceAddressPacket;
-  UINT8                  *Buffer;
+  UINT8                  *BiosBuffer;
+  UINTN                  BiosBufferPages;
+  UINT32                 BiosCrc32;
+  UINT8                  *DiskBuffer;
+  UINTN                  DiskBufferSize;
+  UINT32                 DiskCrc32;
+  BOOLEAN                MatchedDisk;
+
+  //
+  // Read sectors from EFI disk device.
+  //
+  Status = OcDiskInitializeContext (&DiskContext, DiskHandle, TRUE);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  DiskBufferSize = ALIGN_VALUE (BIOS_DISK_CHECK_BUFFER_SECTOR_COUNT * MBR_SIZE, DiskContext.BlockSize);
+  DiskBuffer     = AllocatePool (DiskBufferSize);
+  if (DiskBuffer == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  Status = OcDiskRead (
+             &DiskContext,
+             0,
+             DiskBufferSize,
+             DiskBuffer
+             );
+  if (EFI_ERROR (Status)) {
+    FreePool (DiskBuffer);
+    return Status;
+  }
+
+  gBS->CalculateCrc32 (
+         DiskBuffer,
+         BIOS_DISK_CHECK_BUFFER_SECTOR_COUNT * MBR_SIZE,
+         &DiskCrc32
+         );
+  DEBUG ((DEBUG_INFO, "OLB: EFI disk CRC32: 0x%X\n", DiskCrc32));
 
   //
   // Allocate low memory buffer for disk reads.
   //
   DeviceAddressPacketAddress = (SIZE_1MB - 1);
+  BiosBufferPages            = EFI_SIZE_TO_PAGES (sizeof (*DeviceAddressPacket) + (BIOS_DISK_CHECK_BUFFER_SECTOR_COUNT * MBR_SIZE)) + 1;
   Status                     = gBS->AllocatePages (
                                       AllocateMaxAddress,
                                       EfiBootServicesData,
-                                      EFI_SIZE_TO_PAGES (sizeof (*DeviceAddressPacket) + (MBR_SIZE * 4)) + 1,
+                                      BiosBufferPages,
                                       &DeviceAddressPacketAddress
                                       );
   if (EFI_ERROR (Status)) {
     DEBUG ((DEBUG_INFO, "OLB: Failure allocating low memory packet for BIOS disk read - %r\n", Status));
+    FreePool (DiskBuffer);
     return Status;
   }
 
   DeviceAddressPacket = (DEVICE_ADDRESS_PACKET *)(UINTN)DeviceAddressPacketAddress;
-  Buffer              = (UINT8 *)(UINTN)DeviceAddressPacketAddress + 0x200;
+  BiosBuffer          = (UINT8 *)(UINTN)DeviceAddressPacketAddress + 0x200;
 
   //
-  // Locate disk with matching checksum of first few sectors.
+  // Read sectors from each BIOS disk.
+  // Compare against sectors from EFI disk to determine BIOS disk address.
   //
+  MatchedDisk = FALSE;
   for (DriveAddr = 0x80; DriveAddr < 0x88; DriveAddr++) {
-    DEBUG ((DEBUG_INFO, "drive %X\n", DriveAddr));
+    DEBUG ((DEBUG_INFO, "OLB: Reading BIOS drive 0x%X\n", DriveAddr));
 
     //
     // Reset disk and verify INT13H extensions are supported.
@@ -183,7 +231,7 @@ InternalGetBiosDiskNumber (
     }
 
     //
-    // Read sectors from disk.
+    // Read first 4 sectors from disk.
     //
     Status = BiosDiskReadExtSectors (
                ThunkContext,
@@ -191,15 +239,37 @@ InternalGetBiosDiskNumber (
                DeviceAddressPacket,
                DriveAddr,
                0,
-               4,
-               Buffer
+               BIOS_DISK_CHECK_BUFFER_SECTOR_COUNT,
+               BiosBuffer
                );
     if (EFI_ERROR (Status)) {
       continue;
     }
 
-    DebugPrintHexDump (DEBUG_INFO, "raw bios bytes", Buffer, 512);
+    //
+    // Calculate CRC32 of BIOS disk sectors.
+    //
+    gBS->CalculateCrc32 (
+           BiosBuffer,
+           BIOS_DISK_CHECK_BUFFER_SECTOR_COUNT * MBR_SIZE,
+           &BiosCrc32
+           );
+    DEBUG ((DEBUG_INFO, "OLB: BIOS disk CRC32: 0x%X\n", BiosCrc32));
+
+    if (BiosCrc32 == DiskCrc32) {
+      DEBUG ((DEBUG_INFO, "OLB: Matched BIOS disk address 0x%X\n", DriveAddr));
+
+      MatchedDisk   = TRUE;
+      *DriveAddress = DriveAddr;
+      break;
+    }
   }
 
-  return EFI_SUCCESS;
+  FreePool (DiskBuffer);
+  gBS->FreePages (
+         DeviceAddressPacketAddress,
+         BiosBufferPages
+         );
+
+  return MatchedDisk ? EFI_SUCCESS : EFI_NOT_FOUND;
 }
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index ead42d71326..8464da91d48 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -38,10 +38,11 @@ typedef enum OC_LEGACY_OS_TYPE_ {
 } OC_LEGACY_OS_TYPE;
 
 EFI_STATUS
-InternalGetBiosDiskNumber (
-  IN      THUNK_CONTEXT             *ThunkContext,
-  IN      EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
-  OUT  UINT8                        *DriveNumber
+InternalGetBiosDiskAddress (
+  IN  THUNK_CONTEXT             *ThunkContext,
+  IN  EFI_LEGACY_8259_PROTOCOL  *Legacy8259,
+  IN  EFI_HANDLE                DiskHandle,
+  OUT UINT8                     *DriveNumber
   );
 
 EFI_STATUS
diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index 6195fd70687..a7d97d17abd 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -372,6 +372,7 @@ InternalLoadLegacyPbr (
   MASTER_BOOT_RECORD  *Mbr;
   MASTER_BOOT_RECORD  *Pbr;
   UINT8               PartitionIndex;
+  UINT8               BiosDiskAddress;
 
   IA32_REGISTER_SET         Regs;
   MASTER_BOOT_RECORD        *MbrPtr = (MASTER_BOOT_RECORD *)0x0600;
@@ -452,7 +453,18 @@ InternalLoadLegacyPbr (
   //
   // Determine BIOS disk number.
   //
-  InternalGetBiosDiskNumber (&mThunkContext, Legacy8259, NULL);
+  Status = InternalGetBiosDiskAddress (
+             &mThunkContext,
+             Legacy8259,
+             DiskHandle,
+             &BiosDiskAddress
+             );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_INFO, "OLB: Disk address could not be determined\n"));
+    FreePool (Pbr);
+    FreePool (Mbr);
+    return Status;
+  }
 
   //
   // Copy MBR and PBR to low memory locations for booting.
@@ -470,7 +482,7 @@ InternalLoadLegacyPbr (
   //
   ZeroMem (&Regs, sizeof (Regs));
 
-  Regs.H.DL = 0x80;
+  Regs.H.DL = BiosDiskAddress;
   Regs.X.SI = (UINT16)(UINTN)&MbrPtr->Partition[PartitionIndex];
   OcLegacyThunkFarCall86 (
     &mThunkContext,
@@ -482,9 +494,7 @@ InternalLoadLegacyPbr (
     0
     );
 
-  DEBUG ((DEBUG_INFO, "here\n"));
-  while (TRUE) {
-  }
+  DEBUG ((DEBUG_WARN, "OLB: Failure calling legacy boot sector\n"));
 
-  return EFI_SUCCESS;
+  return EFI_INVALID_PARAMETER;
 }

From 8c96647760338ec945856a6c30cc4baf150552f1 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 20 Aug 2023 13:52:32 -0500
Subject: [PATCH 45/55] Docs: Add BootCampHD to LegacySchema in sample configs

---
 Docs/Sample.plist       | 1 +
 Docs/SampleCustom.plist | 1 +
 2 files changed, 2 insertions(+)

diff --git a/Docs/Sample.plist b/Docs/Sample.plist
index e2d67b1d279..74eae16b3fc 100644
--- a/Docs/Sample.plist
+++ b/Docs/Sample.plist
@@ -1322,6 +1322,7 @@
 				<string>nvda_drv</string>
 				<string>prev-lang:kbd</string>
 				<string>backlight-level</string>
+				<string>BootCampHD</string>
 			</array>
 			<key>8BE4DF61-93CA-11D2-AA0D-00E098032B8C</key>
 			<array>
diff --git a/Docs/SampleCustom.plist b/Docs/SampleCustom.plist
index 1674d07a852..eda903ea1a6 100644
--- a/Docs/SampleCustom.plist
+++ b/Docs/SampleCustom.plist
@@ -1349,6 +1349,7 @@
 				<string>nvda_drv</string>
 				<string>prev-lang:kbd</string>
 				<string>backlight-level</string>
+				<string>BootCampHD</string>
 			</array>
 			<key>8BE4DF61-93CA-11D2-AA0D-00E098032B8C</key>
 			<array>

From bbb7dee447477b304ba3eaaf75d4f73f0aa7d70b Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 20 Aug 2023 14:15:51 -0500
Subject: [PATCH 46/55] BootLoader: Start only boot sector in protective MBR in
 boot0

---
 Legacy/BootLoader/boot0.nasm | 31 +++++--------------------------
 1 file changed, 5 insertions(+), 26 deletions(-)

diff --git a/Legacy/BootLoader/boot0.nasm b/Legacy/BootLoader/boot0.nasm
index e9ca16e83a5..df88ec4c107 100644
--- a/Legacy/BootLoader/boot0.nasm
+++ b/Legacy/BootLoader/boot0.nasm
@@ -90,8 +90,6 @@ kPartTypePMBR       EQU  0xee           ; On all GUID Partition Table disks a Pr
                                         ; reserving the entire space used on the disk by the GPT partitions,
                                         ; including all headers.
 
-kPartActive         EQU  0x80           ; active flag enabled
-kPartInactive       EQU  0x00           ; active flag disabled
 kEFISystemGUID      EQU  0x3BC93EC9     ; last 4 bytes of EFI System Partition Type GUID:
                                         ; C12A7328-F81F-11D2-BA4B-00A0C93EC93B
 kBasicDataGUID      EQU  0xC79926B7     ; last 4 bytes of Basic Data System Partition Type GUID:
@@ -253,8 +251,7 @@ find_boot:
 .loop:
 
     ;
-    ; First scan through the partition table looking for the active
-    ; partition.
+    ; First scan through the partition table looking for the protective MBR.
     ;
 %if DEBUG
     mov     al, [si + part.type]       ; print partition type
@@ -266,36 +263,18 @@ find_boot:
     cmp     BYTE [si + part.type], 0                ; unused partition?
     je      .continue                               ; skip to next entry
     cmp     BYTE [si + part.type], kPartTypePMBR    ; check for Protective MBR
-    jne     .tryToBootIfActive
-
-    mov     BYTE [si + part.bootid], kPartInactive  ; found Protective MBR
-                                                    ; clear active flag to make sure this protective
-                                                    ; partition won't be used as a bootable partition.
-    mov     bl, 1                                   ; Assume we can deal with GPT but try to scan
-                                                    ; later if not found any other bootable partitions.
-
-.tryToBootIfActive:
-    ; We're going to try to boot a partition if it is active
-    cmp     BYTE [si + part.bootid], kPartActive
     jne     .continue
 
-    ;
-    ; Found boot partition, read boot sector to memory.
-    ;
-
-    xor     dh, dh      ; Argument for loadBootSector to skip file system signature check.
-    call    loadBootSector
-    jne     .continue
-    jmp     SHORT initBootLoader
+    mov     bl, 1                                   ; found Protective MBR
+                                                    ; GPT header should be at LBA 1
 
 .continue:
     add     si, BYTE part_size              ; advance SI to next partition entry
     loop    .loop                           ; loop through all partition entries
 
     ;
-    ; Scanned all partitions but not found any with active flag enabled
-    ; Anyway if we found a protective MBR before we still have a chance
-    ; for a possible GPT Header at LBA 1
+    ; Partition scan completed
+    ; If a protective MBR was found there should be a GPT header at LBA 1
     ;
     dec     bl
     jnz     .exit                           ; didn't find Protective MBR before

From cf88226eed0cc1d13716936af02ca4db4ceb5ec0 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sun, 20 Aug 2023 22:09:05 -0500
Subject: [PATCH 47/55] OcLegacyThunkLib: Fix incorrect timer handling

---
 Library/OcLegacyThunkLib/OcLegacyThunkLib.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
index d69d19fd3b4..0cfa3c46973 100644
--- a/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
+++ b/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
@@ -379,9 +379,11 @@ OcLegacyThunkFarCall86 (
                   NULL,
                   (VOID **)&TimerProtocol
                   );
-  if (EFI_ERROR (Status)) {
+  if (!EFI_ERROR (Status)) {
     TimerProtocol->GetTimerPeriod (TimerProtocol, &TimerPeriod);
     TimerProtocol->SetTimerPeriod (TimerProtocol, 0);
+  } else {
+    TimerProtocol = NULL;
   }
 
   //
@@ -446,7 +448,9 @@ OcLegacyThunkFarCall86 (
   //
   // Enable and restore rate of DXE Timer
   //
-  // Private->Timer->SetTimerPeriod (Private->Timer, TimerPeriod);
+  if (TimerProtocol != NULL) {
+    TimerProtocol->SetTimerPeriod (TimerProtocol, TimerPeriod);
+  }
 
   //
   // End critical section

From 4821ae92fbe4961c68f36bf80e6964c28f48454a Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 26 Aug 2023 16:44:49 -0500
Subject: [PATCH 48/55] OpenLegacyBoot: Add support for setting legacy entry as
 default

---
 .../Acidanthera/Library/OcBootManagementLib.h |  18 +++
 .../OcBootManagementLib/BootEntryManagement.c |  13 ++-
 .../OcBootManagementLib/DefaultEntryChoice.c  |  83 ++++++++++----
 Platform/OpenLegacyBoot/LegacyBootInternal.h  |   7 +-
 Platform/OpenLegacyBoot/LegacyBootSupport.c   | 106 ++++++++---------
 Platform/OpenLegacyBoot/OpenLegacyBoot.c      | 107 ++++++++++++++++--
 6 files changed, 238 insertions(+), 96 deletions(-)

diff --git a/Include/Acidanthera/Library/OcBootManagementLib.h b/Include/Acidanthera/Library/OcBootManagementLib.h
index bd15da754f7..8632ad67b0f 100644
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@@ -204,6 +204,16 @@ EFI_STATUS
   IN      EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   );
 
+/**
+  Gets Device Path for external boot system boot entry.
+**/
+typedef
+EFI_STATUS
+(*OC_BOOT_EXTERNAL_SYSTEM_GET_DP) (
+  IN OUT  OC_PICKER_CONTEXT         *PickerContext,
+  IN OUT  EFI_DEVICE_PATH_PROTOCOL  **DevicePath
+  );
+
 /**
   Discovered boot entry.
   Note, inner resources must be freed with FreeBootEntry.
@@ -227,6 +237,10 @@ typedef struct OC_BOOT_ENTRY_ {
   //
   OC_BOOT_EXTERNAL_SYSTEM_ACTION    ExternalSystemAction;
   //
+  // Gets Device Path for external boot system boot entry. Only valid for external boot system entries.
+  //
+  OC_BOOT_EXTERNAL_SYSTEM_GET_DP    ExternalSystemGetDevicePath;
+  //
   // Id under which to save entry as default.
   //
   CHAR16                            *Id;
@@ -627,6 +641,10 @@ typedef struct {
   //
   OC_BOOT_EXTERNAL_SYSTEM_ACTION    ExternalSystemAction;
   //
+  // Gets Device Path for external boot system boot entry. Boot Entry Protocol only. Optional.
+  //
+  OC_BOOT_EXTERNAL_SYSTEM_GET_DP    ExternalSystemGetDevicePath;
+  //
   // External boot system Device Path. Boot Entry Protocol only. Optional.
   //
   EFI_DEVICE_PATH_PROTOCOL          *ExternalSystemDevicePath;
diff --git a/Library/OcBootManagementLib/BootEntryManagement.c b/Library/OcBootManagementLib/BootEntryManagement.c
index 6b2c8a085ba..f0a903ce1c9 100644
--- a/Library/OcBootManagementLib/BootEntryManagement.c
+++ b/Library/OcBootManagementLib/BootEntryManagement.c
@@ -720,12 +720,13 @@ InternalAddBootEntryFromCustomEntry (
     ));
 
   if (CustomEntry->ExternalSystemAction) {
-    BootEntry->Type                 = OC_BOOT_EXTERNAL_SYSTEM;
-    BootEntry->ExternalSystemAction = CustomEntry->ExternalSystemAction;
-    BootEntry->AudioBasePath        = CustomEntry->AudioBasePath;
-    BootEntry->AudioBaseType        = CustomEntry->AudioBaseType;
-    BootEntry->IsExternal           = CustomEntry->External;
-    BootEntry->DevicePath           = DuplicateDevicePath (CustomEntry->ExternalSystemDevicePath);
+    BootEntry->Type                        = OC_BOOT_EXTERNAL_SYSTEM;
+    BootEntry->ExternalSystemAction        = CustomEntry->ExternalSystemAction;
+    BootEntry->ExternalSystemGetDevicePath = CustomEntry->ExternalSystemGetDevicePath;
+    BootEntry->AudioBasePath               = CustomEntry->AudioBasePath;
+    BootEntry->AudioBaseType               = CustomEntry->AudioBaseType;
+    BootEntry->IsExternal                  = CustomEntry->External;
+    BootEntry->DevicePath                  = DuplicateDevicePath (CustomEntry->ExternalSystemDevicePath);
 
     if (BootEntry->DevicePath == NULL) {
       FreeBootEntry (BootEntry);
diff --git a/Library/OcBootManagementLib/DefaultEntryChoice.c b/Library/OcBootManagementLib/DefaultEntryChoice.c
index a51d8472e7a..95e5ec0862f 100644
--- a/Library/OcBootManagementLib/DefaultEntryChoice.c
+++ b/Library/OcBootManagementLib/DefaultEntryChoice.c
@@ -795,6 +795,7 @@ OcSetDefaultBootEntry (
   UINTN            BootChosenIndex;
   UINTN            Index;
   UINTN            DevicePathSize;
+  UINTN            ExtSystemDevPathSize;
   UINTN            LoadOptionSize;
   UINTN            LoadOptionIdSize;
   UINTN            LoadOptionNameSize;
@@ -804,6 +805,7 @@ OcSetDefaultBootEntry (
 
   CONST OC_CUSTOM_BOOT_DEVICE_PATH     *CustomDevPath;
   CONST OC_ENTRY_PROTOCOL_DEVICE_PATH  *EntryProtocolDevPath;
+  EFI_DEVICE_PATH_PROTOCOL             *ExtSystemDevPath;
   VENDOR_DEVICE_PATH                   *DestCustomDevPath;
   FILEPATH_DEVICE_PATH                 *DestCustomEntryName;
   EFI_DEVICE_PATH_PROTOCOL             *DestCustomEndNode;
@@ -822,6 +824,20 @@ OcSetDefaultBootEntry (
     return EFI_INVALID_PARAMETER;
   }
 
+  //
+  // Get final device path for external boot system entries.
+  //
+  ExtSystemDevPath = NULL;
+  if ((Entry->Type == OC_BOOT_EXTERNAL_SYSTEM) && (Entry->ExternalSystemGetDevicePath != NULL)) {
+    ExtSystemDevPath = Entry->DevicePath;
+    Status           = Entry->ExternalSystemGetDevicePath (Context, &ExtSystemDevPath);
+    if (EFI_ERROR (Status)) {
+      ExtSystemDevPath = NULL;
+    } else {
+      ExtSystemDevPathSize = GetDevicePathSize (ExtSystemDevPath);
+    }
+  }
+
   if (Context->CustomBootGuid) {
     BootVariableGuid = &gOcVendorVariableGuid;
     BootOrderName    = OC_VENDOR_BOOT_ORDER_VARIABLE_NAME;
@@ -874,35 +890,42 @@ OcSetDefaultBootEntry (
       continue;
     }
 
-    BootOptionRemainingDevicePath = BootOptionDevicePath;
-    Status                        = gBS->LocateDevicePath (
-                                           &gEfiSimpleFileSystemProtocolGuid,
-                                           &BootOptionRemainingDevicePath,
-                                           &DeviceHandle
-                                           );
-
-    if (!EFI_ERROR (Status)) {
-      MatchedEntry = InternalMatchBootEntryByDevicePath (
-                       Entry,
-                       BootOptionDevicePath,
-                       BootOptionRemainingDevicePath,
-                       LoadOption->FilePathListLength,
-                       FALSE
-                       );
+    if (ExtSystemDevPath != NULL) {
+      DevicePathSize = GetDevicePathSize (BootOptionDevicePath);
+      if (DevicePathSize >= ExtSystemDevPathSize) {
+        MatchedEntry = CompareMem (BootOptionDevicePath, ExtSystemDevPath, ExtSystemDevPathSize) == 0;
+      }
     } else {
-      CustomDevPath = InternalGetOcCustomDevPath (BootOptionDevicePath);
-      if (CustomDevPath != NULL) {
-        MatchedEntry = InternalMatchCustomBootEntryByDevicePath (
+      BootOptionRemainingDevicePath = BootOptionDevicePath;
+      Status                        = gBS->LocateDevicePath (
+                                             &gEfiSimpleFileSystemProtocolGuid,
+                                             &BootOptionRemainingDevicePath,
+                                             &DeviceHandle
+                                             );
+
+      if (!EFI_ERROR (Status)) {
+        MatchedEntry = InternalMatchBootEntryByDevicePath (
                          Entry,
-                         CustomDevPath
+                         BootOptionDevicePath,
+                         BootOptionRemainingDevicePath,
+                         LoadOption->FilePathListLength,
+                         FALSE
                          );
       } else {
-        EntryProtocolDevPath = InternalGetOcEntryProtocolDevPath (BootOptionDevicePath);
-        if (EntryProtocolDevPath != NULL) {
-          MatchedEntry = InternalMatchEntryProtocolEntryByDevicePath (
+        CustomDevPath = InternalGetOcCustomDevPath (BootOptionDevicePath);
+        if (CustomDevPath != NULL) {
+          MatchedEntry = InternalMatchCustomBootEntryByDevicePath (
                            Entry,
-                           EntryProtocolDevPath
+                           CustomDevPath
                            );
+        } else {
+          EntryProtocolDevPath = InternalGetOcEntryProtocolDevPath (BootOptionDevicePath);
+          if (EntryProtocolDevPath != NULL) {
+            MatchedEntry = InternalMatchEntryProtocolEntryByDevicePath (
+                             Entry,
+                             EntryProtocolDevPath
+                             );
+          }
         }
       }
     }
@@ -950,7 +973,9 @@ OcSetDefaultBootEntry (
       }
     }
 
-    if (!Entry->IsCustom) {
+    if (ExtSystemDevPath != NULL) {
+      DevicePathSize = ExtSystemDevPathSize;
+    } else if (!Entry->IsCustom) {
       DevicePathSize = GetDevicePathSize (Entry->DevicePath);
     } else {
       DevicePathSize = SIZE_OF_OC_CUSTOM_BOOT_DEVICE_PATH
@@ -996,7 +1021,10 @@ OcSetDefaultBootEntry (
       CopyMem (LoadOption + 1, LoadOptionName, LoadOptionNameSize);
     }
 
-    if (!Entry->IsCustom) {
+    if (ExtSystemDevPath != NULL) {
+      DebugPrintHexDump (DEBUG_INFO, "hex", (UINT8 *)ExtSystemDevPath, DevicePathSize);
+      CopyMem ((UINT8 *)(LoadOption + 1) + LoadOptionNameSize, ExtSystemDevPath, DevicePathSize);
+    } else if (!Entry->IsCustom) {
       CopyMem ((UINT8 *)(LoadOption + 1) + LoadOptionNameSize, Entry->DevicePath, DevicePathSize);
     } else {
       DestCustomDevPath = (VENDOR_DEVICE_PATH *)(
@@ -1057,6 +1085,11 @@ OcSetDefaultBootEntry (
 
     FreePool (LoadOption);
 
+    if (ExtSystemDevPath != NULL) {
+      FreePool (ExtSystemDevPath);
+      ExtSystemDevPath = NULL;
+    }
+
     if (EFI_ERROR (Status)) {
       DEBUG ((
         DEBUG_INFO,
diff --git a/Platform/OpenLegacyBoot/LegacyBootInternal.h b/Platform/OpenLegacyBoot/LegacyBootInternal.h
index 8464da91d48..df90c24bf39 100644
--- a/Platform/OpenLegacyBoot/LegacyBootInternal.h
+++ b/Platform/OpenLegacyBoot/LegacyBootInternal.h
@@ -50,10 +50,15 @@ InternalIsLegacyInterfaceSupported (
   OUT BOOLEAN  *IsAppleInterfaceSupported
   );
 
+EFI_STATUS
+InternalSetBootCampHDPath (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
+  );
+
 EFI_STATUS
 InternalLoadAppleLegacyInterface (
   IN  EFI_HANDLE                ParentImageHandle,
-  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath,
+  OUT EFI_DEVICE_PATH_PROTOCOL  **ImageDevicePath,
   OUT EFI_HANDLE                *ImageHandle
   );
 
diff --git a/Platform/OpenLegacyBoot/LegacyBootSupport.c b/Platform/OpenLegacyBoot/LegacyBootSupport.c
index a7d97d17abd..412908cbfb3 100644
--- a/Platform/OpenLegacyBoot/LegacyBootSupport.c
+++ b/Platform/OpenLegacyBoot/LegacyBootSupport.c
@@ -11,12 +11,12 @@ THUNK_CONTEXT  mThunkContext;
 // PIWG firmware media device path for Apple legacy interface.
 // FwFile(2B0585EB-D8B8-49A9-8B8CE21B01AEF2B7)
 //
-static CONST UINT8                     AppleLegacyInterfaceMediaDevicePathData[] = {
+STATIC CONST UINT8                     AppleLegacyInterfaceMediaDevicePathData[] = {
   0x04, 0x06, 0x14, 0x00, 0xEB, 0x85, 0x05, 0x2B,
   0xB8, 0xD8, 0xA9, 0x49, 0x8B, 0x8C, 0xE2, 0x1B,
-  0x01, 0xAE, 0xF2, 0xB7, 0x7F, 0xFF, 0x04, 0x00,
+  0x01, 0xAE, 0xF2, 0xB7, 0x7F, 0xFF, 0x04, 0x00
 };
-static CONST EFI_DEVICE_PATH_PROTOCOL  *AppleLegacyInterfaceMediaDevicePathPath = (EFI_DEVICE_PATH_PROTOCOL *)AppleLegacyInterfaceMediaDevicePathData;
+STATIC CONST EFI_DEVICE_PATH_PROTOCOL  *AppleLegacyInterfaceMediaDevicePathPath = (EFI_DEVICE_PATH_PROTOCOL *)AppleLegacyInterfaceMediaDevicePathData;
 
 #define MAX_APPLE_LEGACY_DEVICE_PATHS  16
 
@@ -162,10 +162,8 @@ InternalIsLegacyInterfaceSupported (
 }
 
 EFI_STATUS
-InternalLoadAppleLegacyInterface (
-  IN  EFI_HANDLE                ParentImageHandle,
-  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath,
-  OUT EFI_HANDLE                *ImageHandle
+InternalSetBootCampHDPath (
+  IN  EFI_DEVICE_PATH_PROTOCOL  *HdDevicePath
   )
 {
   EFI_STATUS                Status;
@@ -173,58 +171,60 @@ InternalLoadAppleLegacyInterface (
   EFI_HANDLE                PartitionHandle;
   UINT8                     PartitionIndex;
   EFI_DEVICE_PATH_PROTOCOL  *WholeDiskPath;
-  EFI_DEVICE_PATH_PROTOCOL  **LegacyDevicePaths;
-  CHAR16                    *UnicodeDevicePath;
-  UINTN                     Index;
+
+  WholeDiskPath = OcDiskGetDevicePath (HdDevicePath);
+  if (WholeDiskPath == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy disk device path", WholeDiskPath);
 
   //
-  // Get device path to disk to be booted.
+  // Mark target partition as active.
   //
-  if (!OcIsDiskCdRom (HdDevicePath)) {
-    WholeDiskPath = OcDiskGetDevicePath (HdDevicePath);
-    if (WholeDiskPath == NULL) {
-      return EFI_INVALID_PARAMETER;
-    }
-
-    DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy disk device path", WholeDiskPath);
+  DiskHandle = OcPartitionGetDiskHandle (HdDevicePath);
+  if (DiskHandle == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
 
-    //
-    // Mark target partition as active.
-    //
-    DiskHandle = OcPartitionGetDiskHandle (HdDevicePath);
-    if (DiskHandle == NULL) {
-      return EFI_INVALID_PARAMETER;
-    }
+  PartitionHandle = OcPartitionGetPartitionHandle (HdDevicePath);
+  if (PartitionHandle == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
 
-    PartitionHandle = OcPartitionGetPartitionHandle (HdDevicePath);
-    if (PartitionHandle == NULL) {
-      return EFI_INVALID_PARAMETER;
-    }
+  Status = OcDiskGetMbrPartitionIndex (PartitionHandle, &PartitionIndex);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
 
-    Status = OcDiskGetMbrPartitionIndex (PartitionHandle, &PartitionIndex);
-    if (EFI_ERROR (Status)) {
-      return Status;
-    }
+  Status = OcDiskMarkMbrPartitionActive (DiskHandle, PartitionIndex);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
 
-    Status = OcDiskMarkMbrPartitionActive (DiskHandle, PartitionIndex);
-    if (EFI_ERROR (Status)) {
-      return Status;
-    }
+  //
+  // Set BootCampHD variable pointing to target disk.
+  //
+  return gRT->SetVariable (
+                APPLE_BOOT_CAMP_HD_VARIABLE_NAME,
+                &gAppleBootVariableGuid,
+                EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
+                GetDevicePathSize (WholeDiskPath),
+                WholeDiskPath
+                );
+}
 
-    //
-    // Set BootCampHD variable pointing to target disk.
-    //
-    Status = gRT->SetVariable (
-                    APPLE_BOOT_CAMP_HD_VARIABLE_NAME,
-                    &gAppleBootVariableGuid,
-                    EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
-                    GetDevicePathSize (WholeDiskPath),
-                    WholeDiskPath
-                    );
-    if (EFI_ERROR (Status)) {
-      return Status;
-    }
-  }
+EFI_STATUS
+InternalLoadAppleLegacyInterface (
+  IN  EFI_HANDLE                ParentImageHandle,
+  OUT EFI_DEVICE_PATH_PROTOCOL  **ImageDevicePath,
+  OUT EFI_HANDLE                *ImageHandle
+  )
+{
+  EFI_STATUS                Status;
+  EFI_DEVICE_PATH_PROTOCOL  **LegacyDevicePaths;
+  CHAR16                    *UnicodeDevicePath;
+  UINTN                     Index;
 
   //
   // Get list of possible locations for Apple legacy interface and attempt to load.
@@ -246,9 +246,11 @@ InternalLoadAppleLegacyInterface (
                       ImageHandle
                       );
       if (Status != EFI_NOT_FOUND) {
+        *ImageDevicePath = LegacyDevicePaths[Index];
+
         DEBUG_CODE_BEGIN ();
 
-        UnicodeDevicePath = ConvertDevicePathToText (LegacyDevicePaths[Index], FALSE, FALSE);
+        UnicodeDevicePath = ConvertDevicePathToText (*ImageDevicePath, FALSE, FALSE);
         DEBUG ((
           DEBUG_INFO,
           "OLB: Loaded Apple legacy interface at dp %s - %r\n",
diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index 49bbef4c99c..405ffff80cd 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -12,6 +12,20 @@
 STATIC EFI_HANDLE  mImageHandle;
 STATIC BOOLEAN     mIsAppleInterfaceSupported;
 
+//
+// Fallback PIWG firmware media device path for Apple legacy interface.
+// MemoryMapped(0xB,0xFFE00000,0xFFF9FFFF)/FvFile(2B0585EB-D8B8-49A9-8B8C-E21B01AEF2B7)
+//
+STATIC CONST UINT8                     AppleLegacyInterfaceFallbackDevicePathData[] = {
+  0x01, 0x03, 0x18, 0x00, 0x0B, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0xE0, 0xFF, 0x00, 0x00, 0x00, 0x00,
+  0xFF, 0xFF, 0xF9, 0xFF, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x06, 0x14, 0x00, 0xEB, 0x85, 0x05, 0x2B,
+  0xB8, 0xD8, 0xA9, 0x49, 0x8B, 0x8C, 0xE2, 0x1B,
+  0x01, 0xAE, 0xF2, 0xB7, 0x7F, 0xFF, 0x04, 0x00
+};
+STATIC CONST EFI_DEVICE_PATH_PROTOCOL  *AppleLegacyInterfaceFallbackDevicePathPath = (EFI_DEVICE_PATH_PROTOCOL *)AppleLegacyInterfaceFallbackDevicePathData;
+
 STATIC
 CHAR8 *
 GetLegacyEntryName (
@@ -65,10 +79,22 @@ ExternalSystemActionDoLegacyBoot (
   EFI_STATUS                 Status;
   EFI_HANDLE                 DiskHandle;
   EFI_HANDLE                 LoadedImageHandle;
+  EFI_DEVICE_PATH_PROTOCOL   *LoadedImageDevicePath;
   EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
   BOOLEAN                    IsExternal;
   CONST CHAR8                *AppleBootArg;
 
+  //
+  // Set BootCampHD to desired disk Device Path for non-CD devices.
+  //
+  if (!OcIsDiskCdRom (DevicePath)) {
+    Status = InternalSetBootCampHDPath (DevicePath);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_INFO, "OLB: Failure while setting BootCampHD variable - %r\n", Status));
+      return Status;
+    }
+  }
+
   //
   // Load and start legacy OS.
   //
@@ -84,7 +110,7 @@ ExternalSystemActionDoLegacyBoot (
 
     Status = InternalLoadAppleLegacyInterface (
                mImageHandle,
-               DevicePath,
+               &LoadedImageDevicePath,
                &LoadedImageHandle
                );
     if (EFI_ERROR (Status)) {
@@ -144,6 +170,62 @@ ExternalSystemActionDoLegacyBoot (
   return EFI_SUCCESS;
 }
 
+STATIC
+EFI_STATUS
+ExternalSystemGetDevicePath (
+  IN OUT  OC_PICKER_CONTEXT         *PickerContext,
+  IN OUT  EFI_DEVICE_PATH_PROTOCOL  **DevicePath
+  )
+{
+  EFI_STATUS                Status;
+  EFI_HANDLE                LoadedImageHandle;
+  EFI_DEVICE_PATH_PROTOCOL  *LoadedImageDevicePath;
+  EFI_DEVICE_PATH_PROTOCOL  *AppleLoaderDevicePath;
+
+  //
+  // Set BootCampHD to desired disk Device Path for non-CD devices.
+  //
+  if (!OcIsDiskCdRom (*DevicePath)) {
+    Status = InternalSetBootCampHDPath (*DevicePath);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_INFO, "OLB: Failure while setting BootCampHD variable - %r\n", Status));
+      return Status;
+    }
+  }
+
+  //
+  // Locate Apple legacy interface loader.
+  //
+  // On Macs, use the Apple legacy interface and set BootCampHD.
+  // On other systems, use a default placeholder path.
+  //
+  DebugPrintDevicePath (DEBUG_INFO, "OLB: Legacy device path", *DevicePath);
+  if (mIsAppleInterfaceSupported) {
+    Status = InternalLoadAppleLegacyInterface (
+               mImageHandle,
+               &LoadedImageDevicePath,
+               &LoadedImageHandle
+               );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_INFO, "OLB: Failure while loading Apple legacy interface - %r\n", Status));
+      return Status;
+    }
+
+    gBS->UnloadImage (LoadedImageHandle);
+
+    AppleLoaderDevicePath = DuplicateDevicePath (LoadedImageDevicePath);
+  } else {
+    AppleLoaderDevicePath = DuplicateDevicePath (AppleLegacyInterfaceFallbackDevicePathPath);
+  }
+
+  if (AppleLoaderDevicePath == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  *DevicePath = AppleLoaderDevicePath;
+  return EFI_SUCCESS;
+}
+
 STATIC
 EFI_STATUS
 EFIAPI
@@ -263,17 +345,18 @@ OcGetLegacyBootEntries (
       return Status;
     }
 
-    PickerEntry->Id                       = AsciiDevicePath;
-    PickerEntry->Name                     = GetLegacyEntryName (LegacyOsType);
-    PickerEntry->Path                     = NULL;
-    PickerEntry->Arguments                = NULL;
-    PickerEntry->Flavour                  = GetLegacyEntryFlavour (LegacyOsType);
-    PickerEntry->Tool                     = FALSE;
-    PickerEntry->TextMode                 = FALSE;
-    PickerEntry->RealPath                 = FALSE;
-    PickerEntry->External                 = IsExternal;
-    PickerEntry->ExternalSystemAction     = ExternalSystemActionDoLegacyBoot;
-    PickerEntry->ExternalSystemDevicePath = BlockDevicePath;
+    PickerEntry->Id                          = AsciiDevicePath;
+    PickerEntry->Name                        = GetLegacyEntryName (LegacyOsType);
+    PickerEntry->Path                        = NULL;
+    PickerEntry->Arguments                   = NULL;
+    PickerEntry->Flavour                     = GetLegacyEntryFlavour (LegacyOsType);
+    PickerEntry->Tool                        = FALSE;
+    PickerEntry->TextMode                    = FALSE;
+    PickerEntry->RealPath                    = FALSE;
+    PickerEntry->External                    = IsExternal;
+    PickerEntry->ExternalSystemAction        = ExternalSystemActionDoLegacyBoot;
+    PickerEntry->ExternalSystemGetDevicePath = ExternalSystemGetDevicePath;
+    PickerEntry->ExternalSystemDevicePath    = BlockDevicePath;
 
     if ((PickerEntry->Name == NULL) || (PickerEntry->Flavour == NULL)) {
       OcFlexArrayFree (&FlexPickerEntries);

From ec656dbb8fad5f6d2d01053ea3713f62bcc720a1 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 26 Aug 2023 16:56:27 -0500
Subject: [PATCH 49/55] OcBootManagementLib: Fix previous commit

---
 Library/OcBootManagementLib/DefaultEntryChoice.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Library/OcBootManagementLib/DefaultEntryChoice.c b/Library/OcBootManagementLib/DefaultEntryChoice.c
index 95e5ec0862f..94b36c93759 100644
--- a/Library/OcBootManagementLib/DefaultEntryChoice.c
+++ b/Library/OcBootManagementLib/DefaultEntryChoice.c
@@ -1022,7 +1022,6 @@ OcSetDefaultBootEntry (
     }
 
     if (ExtSystemDevPath != NULL) {
-      DebugPrintHexDump (DEBUG_INFO, "hex", (UINT8 *)ExtSystemDevPath, DevicePathSize);
       CopyMem ((UINT8 *)(LoadOption + 1) + LoadOptionNameSize, ExtSystemDevPath, DevicePathSize);
     } else if (!Entry->IsCustom) {
       CopyMem ((UINT8 *)(LoadOption + 1) + LoadOptionNameSize, Entry->DevicePath, DevicePathSize);

From 48b3beb0c8c057743e9983f685b5b1c97d7d9140 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 26 Aug 2023 17:00:34 -0500
Subject: [PATCH 50/55] OpenDuet: Use PcdTurnOffUsbLegacySupport PCD instead

USB emulation mode should only be disabled for regular OpenDuet build, and not BlockIoDxe one.
---
 Library/DuetBdsLib/BdsPlatform.c | 125 -------------------------------
 OpenDuetPkg.dsc                  |   1 +
 2 files changed, 1 insertion(+), 125 deletions(-)

diff --git a/Library/DuetBdsLib/BdsPlatform.c b/Library/DuetBdsLib/BdsPlatform.c
index 8a14fcffce0..8d6f5a61ed1 100644
--- a/Library/DuetBdsLib/BdsPlatform.c
+++ b/Library/DuetBdsLib/BdsPlatform.c
@@ -519,123 +519,6 @@ UpdateMemoryMap (
   }
 }
 
-STATIC
-EFI_STATUS
-DisableUsbLegacySupport (
-  VOID
-  )
-
-/*++
-
-Routine Description:
-  Disable the USB legacy Support in all Ehci and Uhci.
-  This function assume all PciIo handles have been created in system.
-
-Arguments:
-  None
-
-Returns:
-  EFI_SUCCESS
-  EFI_NOT_FOUND
---*/
-{
-  EFI_STATUS           Status;
-  EFI_HANDLE           *HandleArray;
-  UINTN                HandleArrayCount;
-  UINTN                Index;
-  EFI_PCI_IO_PROTOCOL  *PciIo;
-  UINT8                Class[3];
-  UINT16               Command;
-  UINT32               HcCapParams;
-  UINT32               ExtendCap;
-  UINT32               Value;
-  UINT32               TimeOut;
-
-  //
-  // Find the usb host controller
-  //
-  Status = gBS->LocateHandleBuffer (
-                  ByProtocol,
-                  &gEfiPciIoProtocolGuid,
-                  NULL,
-                  &HandleArrayCount,
-                  &HandleArray
-                  );
-  if (!EFI_ERROR (Status)) {
-    for (Index = 0; Index < HandleArrayCount; Index++) {
-      Status = gBS->HandleProtocol (
-                      HandleArray[Index],
-                      &gEfiPciIoProtocolGuid,
-                      (VOID **)&PciIo
-                      );
-      if (!EFI_ERROR (Status)) {
-        //
-        // Find the USB host controller controller
-        //
-        Status = PciIo->Pci.Read (PciIo, EfiPciIoWidthUint8, 0x09, 3, &Class);
-        if (!EFI_ERROR (Status)) {
-          if ((PCI_CLASS_SERIAL == Class[2]) &&
-              (PCI_CLASS_SERIAL_USB == Class[1]))
-          {
-            if (PCI_IF_UHCI == Class[0]) {
-              //
-              // Found the UHCI, then disable the legacy support
-              //
-              Command = 0;
-              Status  = PciIo->Pci.Write (PciIo, EfiPciIoWidthUint16, 0xC0, 1, &Command);
-            } else if (PCI_IF_EHCI == Class[0]) {
-              //
-              // Found the EHCI, then disable the legacy support
-              //
-              Status = PciIo->Mem.Read (
-                                    PciIo,
-                                    EfiPciIoWidthUint32,
-                                    0,                       ///< EHC_BAR_INDEX
-                                    (UINT64)0x08,            ///< EHC_HCCPARAMS_OFFSET
-                                    1,
-                                    &HcCapParams
-                                    );
-
-              ExtendCap = (HcCapParams >> 8) & 0xFF;
-              //
-              // Disable the SMI in USBLEGCTLSTS firstly
-              // Not doing this may result in a hardlock soon after
-              //
-              PciIo->Pci.Read (PciIo, EfiPciIoWidthUint32, ExtendCap + 0x4, 1, &Value);
-              Value &= 0xFFFF0000;
-              PciIo->Pci.Write (PciIo, EfiPciIoWidthUint32, ExtendCap + 0x4, 1, &Value);
-
-              //
-              // Get EHCI Ownership from legacy bios
-              //
-              PciIo->Pci.Read (PciIo, EfiPciIoWidthUint32, ExtendCap, 1, &Value);
-              Value |= (0x1 << 24);
-              PciIo->Pci.Write (PciIo, EfiPciIoWidthUint32, ExtendCap, 1, &Value);
-
-              TimeOut = 40;
-              while (TimeOut--) {
-                gBS->Stall (500);
-
-                PciIo->Pci.Read (PciIo, EfiPciIoWidthUint32, ExtendCap, 1, &Value);
-
-                if ((Value & 0x01010000) == 0x01000000) {
-                  break;
-                }
-              }
-            }
-          }
-        }
-      }
-    }
-
-    gBS->FreePool (HandleArray);
-  } else {
-    return Status;
-  }
-
-  return EFI_SUCCESS;
-}
-
 STATIC
 EFI_STATUS
 ConnectRootBridge (
@@ -1091,14 +974,6 @@ Routine Description:
     DetectAndPreparePlatformPciDevicePath (TRUE);
   }
 
-  //
-  // The ConIn devices connection will start the USB bus, should disable all
-  // Usb legacy support firstly.
-  // Caution: Must ensure the PCI bus driver has been started. Since the
-  // ConnectRootBridge() will create all the PciIo protocol, it's safe here now
-  //
-  DisableUsbLegacySupport ();
-
   //
   // Connect the all the default console with current console variable
   //
diff --git a/OpenDuetPkg.dsc b/OpenDuetPkg.dsc
index b7af0e37624..2d749013fca 100644
--- a/OpenDuetPkg.dsc
+++ b/OpenDuetPkg.dsc
@@ -245,6 +245,7 @@
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutUgaSupport|FALSE
   gEfiMdeModulePkgTokenSpaceGuid.PcdDevicePathSupportDevicePathFromText|FALSE
   gEfiMdeModulePkgTokenSpaceGuid.PcdDevicePathSupportDevicePathToText|FALSE
+  gEfiMdeModulePkgTokenSpaceGuid.PcdTurnOffUsbLegacySupport|TRUE
   gEfiMdePkgTokenSpaceGuid.PcdUgaConsumeSupport|FALSE
 
 [PcdsFixedAtBuild]

From aca03849fe146b0bbb056e38f7337a41d1c319af Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 26 Aug 2023 19:46:53 -0500
Subject: [PATCH 51/55] OcBootManagementLib: Allow external boot system entries
 to use custom icons

---
 Library/OcBootManagementLib/BootEntryInfo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Library/OcBootManagementLib/BootEntryInfo.c b/Library/OcBootManagementLib/BootEntryInfo.c
index 0f2b937fd55..b150ea334bb 100644
--- a/Library/OcBootManagementLib/BootEntryInfo.c
+++ b/Library/OcBootManagementLib/BootEntryInfo.c
@@ -597,7 +597,7 @@ OcGetBootEntryFile (
   IN  BOOLEAN        SearchAtRoot
   )
 {
-  if ((BootEntry->Type & (OC_BOOT_EXTERNAL_TOOL | OC_BOOT_SYSTEM | OC_BOOT_EXTERNAL_SYSTEM)) != 0) {
+  if ((BootEntry->Type & (OC_BOOT_EXTERNAL_TOOL | OC_BOOT_SYSTEM)) != 0) {
     return EFI_NOT_FOUND;
   }
 

From e8c9724f3a85a26f707c55f44d7baa4b4adf9402 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 26 Aug 2023 19:47:22 -0500
Subject: [PATCH 52/55] OpenCanopy: Fix labels for external boot system entries

---
 Platform/OpenCanopy/Views/BootPicker.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Platform/OpenCanopy/Views/BootPicker.c b/Platform/OpenCanopy/Views/BootPicker.c
index 88b507dae8a..48a8cefe412 100644
--- a/Platform/OpenCanopy/Views/BootPicker.c
+++ b/Platform/OpenCanopy/Views/BootPicker.c
@@ -1453,6 +1453,14 @@ BootPickerEntriesSet (
           Status = EFI_UNSUPPORTED;
         }
 
+        break;
+      case OC_BOOT_EXTERNAL_SYSTEM:
+        if (OcAsciiStriStr (Entry->Flavour, OC_FLAVOUR_WINDOWS) != NULL) {
+          Status = CopyLabel (&VolumeEntry->Label, &GuiContext->Labels[LABEL_WINDOWS]);
+        } else {
+          Status = CopyLabel (&VolumeEntry->Label, &GuiContext->Labels[LABEL_OTHER]);
+        }
+
         break;
       case OC_BOOT_UNKNOWN:
         Status = CopyLabel (&VolumeEntry->Label, &GuiContext->Labels[LABEL_GENERIC_HDD]);

From 608a01ee55e349d886d12ab11b5b28721cce2c68 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 26 Aug 2023 19:47:52 -0500
Subject: [PATCH 53/55] OpenLegacyBoot: Implement custom entry names from
 .contentDetails

---
 Platform/OpenLegacyBoot/OpenLegacyBoot.c | 43 +++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index 405ffff80cd..e45554a9cd9 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -44,6 +44,43 @@ GetLegacyEntryFlavour (
   return AllocateCopyPool (L_STR_SIZE (OC_FLAVOUR_WINDOWS), OC_FLAVOUR_WINDOWS);
 }
 
+STATIC
+CHAR8 *
+LoadAppleDiskLabel (
+  IN OUT  OC_PICKER_CONTEXT  *PickerContext,
+  IN      EFI_HANDLE         DiskHandle
+  )
+{
+  EFI_STATUS                       Status;
+  CHAR8                            *DiskLabel;
+  EFI_SIMPLE_FILE_SYSTEM_PROTOCOL  *FileSystem;
+
+  DiskLabel = NULL;
+  if ((PickerContext->PickerAttributes & OC_ATTR_USE_DISK_LABEL_FILE) != 0) {
+    Status = gBS->HandleProtocol (
+                    DiskHandle,
+                    &gEfiSimpleFileSystemProtocolGuid,
+                    (VOID **)&FileSystem
+                    );
+    if (EFI_ERROR (Status)) {
+      return NULL;
+    }
+
+    DiskLabel = OcReadFile (FileSystem, L".contentDetails", NULL, 0);
+    if (DiskLabel == NULL) {
+      DiskLabel = OcReadFile (FileSystem, L".disk_label.contentDetails", NULL, 0);
+    }
+
+    if (DiskLabel == NULL) {
+      DEBUG ((DEBUG_INFO, "OLB: %s %s not present\n", L".contentDetails", L".disk_label.contentDetails"));
+    } else {
+      DEBUG ((DEBUG_INFO, "OLB: Found disk label '%a'\n", DiskLabel));
+    }
+  }
+
+  return DiskLabel;
+}
+
 STATIC
 VOID
 FreePickerEntry (
@@ -345,8 +382,12 @@ OcGetLegacyBootEntries (
       return Status;
     }
 
+    PickerEntry->Name = LoadAppleDiskLabel (PickerContext, BlockDeviceHandle);
+    if (PickerEntry->Name == NULL) {
+      PickerEntry->Name = GetLegacyEntryName (LegacyOsType);
+    }
+
     PickerEntry->Id                          = AsciiDevicePath;
-    PickerEntry->Name                        = GetLegacyEntryName (LegacyOsType);
     PickerEntry->Path                        = NULL;
     PickerEntry->Arguments                   = NULL;
     PickerEntry->Flavour                     = GetLegacyEntryFlavour (LegacyOsType);

From 7e8555acdb9f23b4cac4929bc43ee91cd54d38c8 Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Sat, 26 Aug 2023 22:36:27 -0500
Subject: [PATCH 54/55] OpenLegacyBoot: Add --hide-devices option

---
 Platform/OpenLegacyBoot/OpenLegacyBoot.c | 89 +++++++++++++++++++-----
 1 file changed, 73 insertions(+), 16 deletions(-)

diff --git a/Platform/OpenLegacyBoot/OpenLegacyBoot.c b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
index e45554a9cd9..1a157a2f2e2 100644
--- a/Platform/OpenLegacyBoot/OpenLegacyBoot.c
+++ b/Platform/OpenLegacyBoot/OpenLegacyBoot.c
@@ -12,6 +12,8 @@
 STATIC EFI_HANDLE  mImageHandle;
 STATIC BOOLEAN     mIsAppleInterfaceSupported;
 
+STATIC OC_FLEX_ARRAY  *mHiddenDevicePaths;
+
 //
 // Fallback PIWG firmware media device path for Apple legacy interface.
 // MemoryMapped(0xB,0xFFE00000,0xFFF9FFFF)/FvFile(2B0585EB-D8B8-49A9-8B8C-E21B01AEF2B7)
@@ -277,12 +279,15 @@ OcGetLegacyBootEntries (
   UINTN       NoHandles;
   EFI_HANDLE  *Handles;
   UINTN       HandleIndex;
+  UINTN       DevicePathIndex;
+  BOOLEAN     SkipHiddenDevice;
   UINT32      ScanPolicy;
   BOOLEAN     IsExternal;
 
   CHAR16  *UnicodeDevicePath;
   CHAR8   *AsciiDevicePath;
   UINTN   AsciiDevicePathSize;
+  CHAR16  **HiddenUnicodeDevicePath;
 
   EFI_HANDLE                BlockDeviceHandle;
   EFI_DEVICE_PATH_PROTOCOL  *BlockDevicePath;
@@ -334,14 +339,6 @@ OcGetLegacyBootEntries (
       continue;
     }
 
-    //
-    // Detect legacy OS type.
-    //
-    LegacyOsType = InternalGetPartitionLegacyOsType (BlockDeviceHandle, mIsAppleInterfaceSupported);
-    if (LegacyOsType == OcLegacyOsTypeNone) {
-      continue;
-    }
-
     BlockDevicePath = DevicePathFromHandle (BlockDeviceHandle);
     if (BlockDevicePath == NULL) {
       DEBUG ((DEBUG_INFO, "OLB: Could not find Device Path for block device\n"));
@@ -349,19 +346,51 @@ OcGetLegacyBootEntries (
     }
 
     //
-    // Create and add picker entry to entries.
+    // Device Path will be used as ID and is required for default entry matching.
     //
-    PickerEntry = OcFlexArrayAddItem (FlexPickerEntries);
-    if (PickerEntry == NULL) {
+    UnicodeDevicePath = ConvertDevicePathToText (BlockDevicePath, FALSE, FALSE);
+    if (UnicodeDevicePath == NULL) {
       OcFlexArrayFree (&FlexPickerEntries);
       return EFI_OUT_OF_RESOURCES;
     }
 
     //
-    // Device Path will be used as ID and is required for default entry matching.
+    // Skip device if on hidden list.
     //
-    UnicodeDevicePath = ConvertDevicePathToText (BlockDevicePath, FALSE, FALSE);
-    if (UnicodeDevicePath == NULL) {
+    if (mHiddenDevicePaths != NULL) {
+      SkipHiddenDevice = FALSE;
+      for (DevicePathIndex = 0; DevicePathIndex < mHiddenDevicePaths->Count; DevicePathIndex++) {
+        HiddenUnicodeDevicePath = (CHAR16 **)OcFlexArrayItemAt (mHiddenDevicePaths, DevicePathIndex);
+        ASSERT (HiddenUnicodeDevicePath != NULL);
+
+        if (StrCmp (UnicodeDevicePath, *HiddenUnicodeDevicePath) == 0) {
+          DEBUG ((DEBUG_INFO, "OLB: Skipping hidden device %s\n", *HiddenUnicodeDevicePath));
+          SkipHiddenDevice = TRUE;
+          break;
+        }
+      }
+
+      if (SkipHiddenDevice) {
+        FreePool (UnicodeDevicePath);
+        continue;
+      }
+    }
+
+    //
+    // Detect legacy OS type.
+    //
+    LegacyOsType = InternalGetPartitionLegacyOsType (BlockDeviceHandle, mIsAppleInterfaceSupported);
+    if (LegacyOsType == OcLegacyOsTypeNone) {
+      FreePool (UnicodeDevicePath);
+      continue;
+    }
+
+    //
+    // Create and add picker entry to entries.
+    //
+    PickerEntry = OcFlexArrayAddItem (FlexPickerEntries);
+    if (PickerEntry == NULL) {
+      FreePool (UnicodeDevicePath);
       OcFlexArrayFree (&FlexPickerEntries);
       return EFI_OUT_OF_RESOURCES;
     }
@@ -450,9 +479,37 @@ UefiMain (
   IN EFI_SYSTEM_TABLE  *SystemTable
   )
 {
-  EFI_STATUS  Status;
+  EFI_STATUS                 Status;
+  EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage;
+  CHAR16                     *DevicePathNames;
+  OC_FLEX_ARRAY              *ParsedLoadOptions;
+
+  Status = gBS->HandleProtocol (
+                  ImageHandle,
+                  &gEfiLoadedImageProtocolGuid,
+                  (VOID **)&LoadedImage
+                  );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
 
-  mImageHandle = ImageHandle;
+  mImageHandle       = ImageHandle;
+  mHiddenDevicePaths = NULL;
+
+  Status = OcParseLoadOptions (LoadedImage, &ParsedLoadOptions);
+  if (!EFI_ERROR (Status)) {
+    OcParsedVarsGetUnicodeStr (ParsedLoadOptions, L"--hide-devices", &DevicePathNames);
+    if (DevicePathNames != NULL) {
+      mHiddenDevicePaths = OcStringSplit (DevicePathNames, L';', OcStringFormatUnicode);
+      if (mHiddenDevicePaths == NULL) {
+        return EFI_OUT_OF_RESOURCES;
+      }
+    }
+  } else {
+    if (Status != EFI_NOT_FOUND) {
+      return Status;
+    }
+  }
 
   Status = InternalIsLegacyInterfaceSupported (&mIsAppleInterfaceSupported);
   if (EFI_ERROR (Status)) {

From f9a6965f4e88662bc419532b1cb4fad335162a0a Mon Sep 17 00:00:00 2001
From: John Davis <goldfishnet64@outlook.com>
Date: Mon, 4 Sep 2023 18:47:39 -0500
Subject: [PATCH 55/55] OcFileLib: Use ReadUnaligned32 for MBR table checks

---
 Library/OcFileLib/DiskMisc.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/Library/OcFileLib/DiskMisc.c b/Library/OcFileLib/DiskMisc.c
index 0c4eb67c75d..ca4407a5133 100644
--- a/Library/OcFileLib/DiskMisc.c
+++ b/Library/OcFileLib/DiskMisc.c
@@ -881,12 +881,14 @@ OcGetDiskMbrTable (
 
   if (CheckPartitions) {
     if (  (Mbr->Partition[0].OSIndicator == PMBR_GPT_PARTITION)
-       && (*((UINT32 *)Mbr->Partition[0].StartingLBA) == 0x01)
-       && (*((UINT32 *)Mbr->Partition[0].SizeInLBA) != 0))
+       && (ReadUnaligned32 ((UINT32 *)Mbr->Partition[0].StartingLBA) == 0x01)
+       && (ReadUnaligned32 ((UINT32 *)Mbr->Partition[0].SizeInLBA) != 0))
     {
       IsProtectiveMbr = TRUE;
       for (Index = 1; Index < MAX_MBR_PARTITIONS; Index++) {
-        if ((*((UINT32 *)Mbr->Partition[Index].StartingLBA) != 0) || (*((UINT32 *)Mbr->Partition[Index].SizeInLBA) != 0)) {
+        if (  (ReadUnaligned32 ((UINT32 *)Mbr->Partition[Index].StartingLBA) != 0)
+           || (ReadUnaligned32 ((UINT32 *)Mbr->Partition[Index].SizeInLBA) != 0))
+        {
           IsProtectiveMbr = FALSE;
           break;
         }
@@ -958,8 +960,8 @@ OcDiskGetMbrPartitionIndex (
 
   Status = EFI_NOT_FOUND;
   for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
-    if (  (*((UINT32 *)Mbr->Partition[Index].StartingLBA) == HdNode->PartitionStart)
-       && (*((UINT32 *)Mbr->Partition[Index].SizeInLBA) == HdNode->PartitionSize))
+    if (  (ReadUnaligned32 ((UINT32 *)Mbr->Partition[Index].StartingLBA) == HdNode->PartitionStart)
+       && (ReadUnaligned32 ((UINT32 *)Mbr->Partition[Index].SizeInLBA) == HdNode->PartitionSize))
     {
       *PartitionIndex = Index;
       Status          = EFI_SUCCESS;