Welcome to KFS

KFS (Kernel From Scratch) is a long-term educational project developed at 42 Wolfsburg that explores the foundations of operating system design by building a kernel step by step, starting from nothing. Rather than relying on existing kernels or high-level abstractions, this project focuses on understanding how things actually work at the lowest level of a computer system.

The project is divided into multiple stages (kfs-1 to kfs-x), each introducing new core concepts such as booting, memory management, interrupts, multitasking, and hardware interaction. Every stage builds upon the previous one, gradually transforming a minimal bootable binary into a functional and extensible kernel.

KFS currently features:

• GDT setup
• Framebuffer output
• Paging
• Preemptive multitasking
• Reentrancy
• ATA disk support
• FPU (Lazy context switching)
• VFS
• Ext2 filesystem support
• Device files
• Procfs, Sysfs
• Userspace programs
• TTY subsystem
• VT Parsing
• Kernel modules
• Standard POSIX Signals
• IPC with socketpairs and Unix pipes.

Commands

• make - Compile the project
• make qemu - Compile and run the project
• make clean - Remove the kernel binary.
• make fclean - Remove the kernel binary, iso and all other compilation generated files.

Project layout

docs/ # Documentation
    kfs/
        docs
iso # ISO configuration files
    boot/
        grub/
src/ # Source code
    arch/
        x86/
            boot/
            mm/
            system/
    debug/
    drivers/
    kernel/
        irq/
        mm/
        sched/
        syscalls/
        time/
        userspace/
        utils/
    mm/
    userspace/
userspace # Zig userspace programs
    src
zig-out # Kernel binary output directory
    bin