Crescent

A custom OS distribution

Crescent is a custom operating system distribution, that is going to come with its own set of userspace applications and a desktop environment.

This repository hosts the Crescent kernel and apps.

Features

• Multithreaded pre-emptive custom kernel
• A set of custom userspace applications including a terminal, file manager, desktop environment, browser, media player and some games. (TODO, currently the only userspace application is a very basic desktop environment)
• Works on real hardware and supports different kinds of devices
• Architectures supported: X86-64, AArch64

Building the kernel and apps

The required tools for building are:

• C/C++ compiler
• CMake
• Ninja (or Make, but the steps below assume Ninja is used)

Steps

Note: If you want to cross-compile to a different architecture, there are some pre-defined cmake toolchain files in cmake folder that you can use by adding -DCMAKE_TOOLCHAIN_FILE=<path to toolchain file> to the cmake commandline. If there isn't an existing toolchain for the target that you want to build for then refer to the existing toolchains and CMake documentation on toolchain files and create a new one.

• mkdir build
• cd build
• cmake -G Ninja ..
• ninja

There are also different targets that may be useful:

run target for running the kernel in Qemu

• ninja run

debug target that runs the kernel in qemu and also launches remote gdb

• ninja debug
• gdb bin/crescent
• in gdb: target remote localhost:1234

boot.img target on AArch64 to create an android boot image (needs mkbootimg)

• ninja boot.img

Todo

• Basic logging
• Memory
  • Page frame allocator
  • Page table manager
  • General purpose memory allocator
• Interrupt handling
  • APIC
  • Exceptions
  • IO-APIC
• Kernel module loading
• Per-cpu multilevel feedback queue scheduler
• ACPI
  • FADT
  • MADT
  • MCFG
  • Reboot + shutdown
  • Power management
    • Shutdown
    • Reboot
    • Sleep
• Filesystems
  • TAR initramfs
  • FAT32
  • Ext4 read
  • Ext4 write
• Drivers
  • SMP
  • AHCI SATA
  • NVMe
  • Audio
    • Intel High Definition Audio (mostly done)
  • PS2
    • Keyboard
    • Mouse
  • Generic PCI device interface
  • Ethernet
    • Realtek RTL8169/RTL8139
  • Network stack
    • Ethernet
    • ARP
    • IPv4
    • IPv6
    • UDP v4
    • UDP v6
    • TCP v4 (mostly done)
    • TCP v6
  • USB
    • Generic HCI interface abstraction
    • HCI
      • UHCI
      • OHCI
      • EHCI
      • XHCI
    • Keyboard
    • Mouse
    • Mass storage
    • RNDIS (used eg. for tethering internet from a phone)
• Apps
  • Desktop environment (very basic one with almost no functionality is done)
  • Web browser
  • Terminal
  • File manager
  • Media player