kfs

This is our repository for 42's kfs (kernel from scratch) project. The aim is to build a fully functional 32-bit kernel.

Running the Kernel

qemu and grub-mkrescue are very specific about their mutual versions, so we made a DevContainer to make it work on every Linux machine.

Clone kfs

git clone [email protected]:kentucky-fried-kernel/kfs.git && cd kfs

VSCode

If you are in VSCode, you can just install the Dev Container extension. Once installed, VSCode will prompt you to "Rebuild and Reopen in Container". The first time will take a while, as a whole Docker Image has to be built.

Note: If you do not get the Dev Container prompt, you can also open the VSCode settings (Ctrl/Cmd+Shift+P) and search for 'Dev Container: Rebuild and Reopen in Container'.

Shell

If you don't have VSCode, you can:

# Build the Docker Image
docker build -f .devcontainer/Dockerfile -t kfs .devcontainer 
# Mount the kernel code and run it
docker run -v .:/root -it kfs bash

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If you have a window manager you can now run make run, which will run our kernel in a qemu window.

If you have a headless system you can now run make debug, which will run the kernel in your shell.

Requirements

This project is separated into 10 subprojects.

• kfs-1
  • Bootable via GRUB
  • ASM multiboot header
  • Basic kernel library
  • Basic code to print stuff on the screen
  • Scroll and cursor support
  • I/O interface with colors support
  • Handles keyboard entries
  • Handles different screens with shortcuts to switch between them
• kfs-2
  • Implements Global Descriptor Table (GDT)
    • Kernel Code
    • Kernel Data
    • Kernel Stack
    • User Code
    • User Data
    • User Stack
    • GDT must be set at address 0x000008000
  • Tool to print the kernel stack
  • Basic shell with commands like reboot, halt, etc.
• kfs-3
  • Complete memory code structure with pagination
  • Read/Write operations on memory
  • User Space and Kernel Space memory
  • Physical and Virtual memory
  • Allocators
  • Kernel Panic handling
• kfs-4
  • Hardware Interrupts
  • Software Interrupts
  • Interrup Descriptor Table (IDT)
  • Signal Handling and Scheduling
  • Global Panic Fault handling
  • Panic & System Exit commands
    • Registers cleaning
    • Stack saving
  • Base functions for syscalls
  • Different keyboard layouts
• kfs-5
  • Basic data structure for processes
  • Process interconnection (signals, sockets, etc.)
  • Process owner
  • Process rights
  • Process interruptions
  • Process memory separation
  • Multitasking
  • mmap
  • Link IDT and processes
  • BSS and Data sectors in the process structure
• kfs-6
  • IDE
  • Read/Write/Delete an ext2 filesystem
  • Basic file tree (/sys, /var, /dev, /proc)
  • Multiple partitions
  • Users
• kfs-7
  • Complete syscall table
  • Complete Unix environment
  • Password protection
  • Inter-Process Communication socket
  • Unix-like filesystem hierarchy
  • Console environments
• kfs-8
  • Kernel modules
  • Loading modules at boot time
  • Functions for communication / callback between kernel and modules
  • Special memory allocator functions to create memory ring dedicated to the modules
• kfs-9
  • Complete interface to read, parse and execute ELF files
  • Syscalls to read ELF files and launch a process with them
  • Kernel module in ELF ready to be inserted at run time
  • Memory ring for the modules (built-in and run-time modules)
• kfs-x
  • Fully functional binaries
  • libc
  • Posix Shell