start adding toolchain for cross-compiling for FreeBSD

CMakePresets.json

@@ -180,7 +180,7 @@
         "CMAKE_C_COMPILER": "clang",
         "CMAKE_CXX_COMPILER": "clang++",
         "VCPKG_TARGET_TRIPLET": "x64-freebsd",
-        "VCPKG_CHAINLOAD_TOOLCHAIN_FILE": "${sourceDir}/toolchains/FreeBSD-x64.cmake"
+        "VCPKG_CHAINLOAD_TOOLCHAIN_FILE": "${sourceDir}/toolchains/FreeBSD-x86_64.cmake"
       }
     },
     {

toolchains/FreeBSD-x86_64.cmake

@@ -0,0 +1,33 @@
+# Toolchain file for building for FreeBSD from Linux
+
+# Set the system name to reflect the target environment
+set(CMAKE_SYSTEM_NAME FreeBSD)
+
+# Specify the target architecture
+set(CMAKE_SYSTEM_PROCESSOR x86_64)
+
+# Specify the cross-compiler locations. These paths might need to be adjusted
+# based on where the cross-compilers are installed on your system.
+set(CMAKE_C_COMPILER /usr/bin/clang)
+set(CMAKE_CXX_COMPILER /usr/bin/clang++)
+
+# You might need to specify the sysroot if you have a FreeBSD sysroot available on your Linux machine.
+# This is especially necessary for finding the target system's libraries and headers.
+# set(CMAKE_SYSROOT /path/to/freebsd-sysroot)
+
+# Ensure that the compiler can find includes and link against libraries for the target environment
+# This might include specifying the path to the target's libc and other essential libraries.
+# Example:
+# set(CMAKE_FIND_ROOT_PATH /path/to/freebsd-sysroot)
+
+# Tell CMake to look for programs in the native build host first.
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers, since we are cross-compiling, we don't want to use the host's libraries/headers.
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+
+# Optionally, you can set compiler flags specific to your project's needs or to optimize for the target architecture
+# set(CMAKE_C_FLAGS "-target x86_64-unknown-freebsd11 --sysroot=${CMAKE_SYSROOT}" CACHE STRING "")
+# set(CMAKE_CXX_FLAGS "-target x86_64-unknown-freebsd11 --sysroot=${CMAKE_SYSROOT}" CACHE STRING "")
+