A custom x86_64 kernel written in Rust, heavily based on the excellent “Writing an OS in Rust” series by Philipp Oppermann. This project started as a learning exercise following that tutorial, and has since been extended with custom features (ATA PIO driver, FAT-like file system, cooperative multitasking, user-mode switching, syscall stubs, etc.). Currently boots via UEFI, sets up 4-level paging, and can execute user-mode code in Ring 3.

Status: Active development (v0.3.0). Learning project for low-level x86_64 architecture and bare-metal Rust.

What works (mostly)

• Boots on QEMU and real hardware (UEFI).
• Simple FAT-like file system on top of the ATA driver.
• GDT / TSS setup with working Ring 0 → Ring 3 transition via iretq.
• 4-level paging with isolated user-accessible pages.
• Cooperative async task executor (PS/2 keyboard driver, hlt on idle).
• Custom kernel heap allocator (fixed-size block allocator).
• ATA PIO driver (reads sectors in QEMU, DMA is still broken on bare metal – help wanted!).

What doesn't work yet

• Proper IPC (inter-process communication) - so it's not really a microkernel yet.
• Syscalls (just a stub, not wired up).
• DMA bus mastering for the ATA driver.

Quick Start

Prerequisites: Rust nightly + qemu-system-x86_64.

Clone and run in QEMU

cargo run -Zjson-target-spec

Build a standalone bootable image

cargo install bootimage
cargo bootimage

Output: target/x86_64-daxo_os/debug/bootimage-daxo_os.bin

The hardest part so far:

Setting up the Task State Segment (TSS) with the correct Interrupt Stack Table (IST) to avoid triple faults when switching to Ring 3. Took two weeks of staring at QEMU register dumps until I realised I'd misconfigured the stack pointer for the privilege level change. The ATA DMA failing on real hardware (while working in QEMU) is the current headache – if you've debugged PCI IDE BARs without UEFI Disk I/O, I'd love to hear from you.

License

MIT / Apache-2.0

Repo: https://github.com/daxo-developer/daxo_os

Web resources:

https://daxo-developer.github.io/

https://daxo-developer.github.io/daxo-binary-anylazer/

https://daxo-developer.github.io/daxo-os-gallery-web/

https://daxo-developer.github.io/daxo-os-webreboot/

https://daxo-developer.github.io/daxo-os-website/

https://daxo-developer.github.io/daxo.sh/

https://daxo-developer.github.io/dx-wasm/

https://daxo-developer.github.io/The-Daxo-OS-Macro-Cosmic-PCB/