A UEFI-native x86_64 research operating system written in Rust, with an NT-inspired kernel that runs real Linux ELF binaries.

AstryxOS is a from-scratch operating system kernel (codename Aether) that takes the NT subsystem model as its architectural inspiration: a microkernel-ish executive at the centre, with personality subsystems layered above the HAL that give each application binary the illusion of running on its native operating system. The practical result is that unmodified upstream binaries run on AstryxOS — and the headline result is that upstream Firefox (musl ESR-115, GTK3) now runs as a windowed application on the in-kernel X11 compositor and renders real HTTPS web content, with no source modifications to the browser. The project is also an experiment in agentic software development: the bulk of the ~200 KLOC of Rust (kernel, bootloader, and the in-tree test suite) was written by Claude agents working in parallel worktrees, with human review at merge time.

Upstream Firefox rendering example.com over HTTPS on AstryxOS — chrome, TLS lock, and page content all painted by the in-kernel X11 server and software compositor. The browser binary is unmodified.

• Upstream Firefox (musl ESR-115, GTK3) runs windowed on the in-kernel X11 compositor and renders real HTTPS web content — for example.com the browser chrome, the TLS-secured navigation, and the page content all paint to verified pixels, with an unmodified browser binary. Heavier sites (e.g. Wikipedia) load over TLS and paint the browser chrome; full content compositing for large pages is the active focus.
• Unmodified glibc- and musl-linked ELF binaries run end-to-end (dynamic linker fully wired)
• Full TCP/IP stack (IPv4, IPv6, 3WHS, FIN, retransmit, congestion control, DHCP, DNS) — Firefox fetches real sites over HTTPS
• In-kernel X11 server with RENDER, MIT-SHM, XKB, XFIXES, SYNC, BIG-REQUESTS extensions, driving a software compositor that blits to the framebuffer
• 193 Linux syscalls dispatched; 50+ native Aether syscalls
• FAT32 read-write, ext2 read-only, NTFS read-only, procfs, tmpfs
• ~130 KLOC across 200+ Rust source files in kernel/src (including a 56K-line in-tree test suite); ~200 KLOC of Rust repo-wide

Full step-by-step instructions are in docs/QUICKSTART.md.

Short version (Ubuntu 22.04 / WSL2):

# 1. Install system dependencies
sudo apt-get install -y build-essential gcc musl-tools mtools qemu-system-x86 ovmf python3

# 2. Install Rust nightly
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
source "$HOME/.cargo/env"
rustup toolchain install nightly && rustup component add rust-src --toolchain nightly

# 3. Clone and build
git clone <repo-url> AstryxOS && cd AstryxOS
./build.sh release
bash scripts/create-data-disk.sh

# 4. Run the test suite
python3 scripts/watch-test.py --idle-timeout 60 --hard-timeout 300

A passing run ends with [PASS] for the headless integration suite.

Upstream Firefox runs as a windowed app on the in-kernel X11 compositor via the QEMU harness (KVM recommended; SMP=1 for the browser):

# Boot windowed Firefox against a real site (renders example.com content to verified pixels)
python3 scripts/qemu-harness.py start \
    --features firefox-test-core,kdb --smp 1 --ff-gui \
    --ff-url https://example.com

# Capture a screenshot of the live framebuffer
python3 scripts/qemu-harness.py screendump <sid> firefox.png

See docs/FIREFOX_PORT_ROADMAP.md for the milestone tracker and docs/HARNESS.md for the full harness reference.

AstryxOS/
├── bootloader/         # AstryxBoot — custom UEFI bootloader
├── kernel/
│   └── src/
│       ├── arch/       # x86_64: GDT, IDT, LAPIC, SMP, context switch
│       ├── drivers/    # ATA, AHCI, virtio-blk/net, AC97, PS/2, xHCI, serial
│       ├── gdi/        # GDI engine: DC, surfaces, BitBlt, text, regions
│       ├── gui/        # Window manager, compositor, terminal, desktop
│       ├── hal/        # Hardware Abstraction Layer
│       ├── ipc/        # Pipes, Unix sockets, SysV SHM, timerfd, signalfd
│       ├── ke/         # Core executive: spinlocks, DPCs, wait/notify
│       ├── mm/         # PMM, VMM, heap, page tables, ASLR, OOM killer
│       ├── net/        # TCP/IP stack, DNS, DHCP, e1000, virtio-net
│       ├── nt/         # NT personality subsystem (Win32 ABI)
│       ├── ob/         # Object manager (handles, reference counting)
│       ├── proc/       # Process and thread control blocks, ELF/PE loader
│       ├── sched/      # CoreSched — SMP round-robin + priority
│       ├── security/   # Capabilities, rlimits, prctl
│       ├── subsys/
│       │   ├── aether/ # Native Aether syscall dispatch
│       │   ├── linux/  # Linux syscall dispatch (193 syscalls)
│       │   └── win32/  # Win32 syscall dispatch stub
│       ├── syscall/    # Syscall entry point and routing
│       ├── vfs/        # VFS layer: ramfs, FAT32, ext2, NTFS, procfs, tmpfs
│       ├── x11/        # In-kernel X11 server
│       └── test_runner.rs  # 143 headless integration tests
├── shared/             # Types shared between bootloader and kernel
├── tools/              # Host-side utilities
├── scripts/
│   ├── watch-test.py       # Test watchdog — primary CI entry point
│   ├── qemu-harness.py     # Agentic QEMU session manager
│   ├── create-data-disk.sh # Build build/data.img
│   ├── build-musl.sh       # Build musl libc for the data disk
│   ├── install-glibc.sh    # Install glibc dynamic linker + libs
│   └── run-qemu.sh         # Manual QEMU launcher (interactive)
├── docs/
│   ├── QUICKSTART.md
│   ├── HARNESS.md
│   ├── DEVELOPMENT_PLAN.md
│   ├── FIREFOX_PORT_ROADMAP.md
│   └── SOURCE_REVIEW_2026-04-20.md
├── build.sh            # Manual build script
└── rust-toolchain.toml # Pins nightly toolchain version

See CONTRIBUTING.md for the contributor workflow.

For what to work on:

• Browse the issue tracker
• Good starting points: good first issue
• AI agents welcome: agent-friendly
• Community wishlist: help wanted

The roadmap project shows active waves and backlog.

Human contributors: HUMAN_CONTRIBUTING.md. AI agents: AI_CONTRIBUTING.md.

MIT. See LICENSE.

Copyright (c) 2026 Melissa and AstryxOS Contributors.

• ReactOS — clean-room NT ABI reference implementation (MIT licensed)
• musl libc authors — clean, auditable C library that runs on Aether today
• Linux kernel authors — syscall ABI and POSIX semantics reference
• Mozilla — Firefox ESR is the target application that drives RC1 requirements
• uefi-rs maintainers — Rust UEFI bindings used in the bootloader