CoreOS

CoreOS is an experimental AMD64 operating system with a Rust no_std kernel, a small C UEFI bootloader, and a minimal C userspace.

Current State

The tree boots through UEFI into the kernel, initializes memory management, interrupts, scheduling, VFS, and syscall handling, runs embedded ring 3 test ELFs, and then starts a userspace shell from an in-memory filesystem.

Current syscall work is aimed at a future musl (libc) port. Several Linux-numbered syscalls are already implemented and exercised at boot, but the ABI is not yet Linux-compatible enough for an unmodified musl userspace.

Includes

• UEFI boot path and higher-half kernel handoff
• AMD64 paging, PMM, heap allocation, and task/process support
• Preemptive scheduler and ring 3 ELF loading
• RamFS-backed VFS and pipe-backed file descriptors
• Framebuffer console, PS/2 keyboard, PIT, RTC, and serial output
• Minimal libc shim plus embedded syscall regression tests

Build

Requirements:

• Rust nightly
• clang and lld
• QEMU
• OVMF
• mtools

Build and run:

make
make run

make produces a bootable image at build/coreos.img.

Repository Layout

bootloader/   UEFI loader
kernel/       Rust kernel
user/         Userspace programs and libc shim
assets/       Fonts and static assets
build/        Generated build artifacts
Makefile      Top-level build and run targets