Orbox

A clean-room, open-source operating system that natively runs Windows applications: x86_64 code executes directly on the CPU — no emulation, no JIT translation — behind an NT-style kernel environment and a Win32 subsystem.

Status: Milestone 0 (bootstrap) complete. Next: Milestone 1 — UEFI boot prototype. See STATUS.md and ROADMAP.md.

What Orbox is

Orbox targets a specific, honest goal: the ability to run unmodified Windows executables as first-class citizens of a native OS. Windows programs speak two languages: the machine (x86_64 instructions) and the system (NT/Win32 API surface). Orbox speaks both. Machine code runs untranslated; the system-call surface is re-implemented by an NT-style executive and a Win32 compatibility subsystem, so applications cannot distinguish the host.

What Orbox is not: an emulator, a VM wrapper around existing Windows components, or a Linux distribution with a compatibility shim. No code, headers, or assets from Microsoft are used; everything is written from scratch against publicly documented behavior, verified by black-box testing.

Quick start

Requirements: Rust 1.99.1 (pinned via rust-toolchain.toml), QEMU 8+, OVMF firmware. Full setup guide: docs/build.md.

# Environment audit — verify your host is ready
cargo xtask info

# Build, test, format, lint (all exit 0 on success)
cargo xtask build
cargo xtask test
cargo xtask fmt
cargo xtask lint

# Not implemented yet — land in Milestone 1 (exit code 3)
cargo xtask run
cargo xtask test-boot

Exit-code convention (project-wide): 0 success · 1 failure · 2 usage error · 3 not implemented.

Repository layout

Cargo.toml            workspace manifest
rust-toolchain.toml   pinned toolchain (1.99.1)
xtask/                build automation (std-only, zero dependencies)
docs/
  build.md            toolchain + QEMU/OVMF setup, acceleration notes
  budget.md           performance/size budget framework (no invented numbers)
  architecture/       architecture decision records (ADR 0001–0006)
licenses/             canonical license texts (MPL-2.0, Apache-2.0)
reports/              milestone reports and environment audits

Licensing

Dual licensing by component (ADR 0002):

Scope	License	Rationale
boot, kernel, drivers	MPL-2.0	file-level copyleft keeps the OS core open
runtime, compat, crates, tools, xtask, docs	Apache-2.0	permissive for the application/tooling ecosystem

See LICENSE.md for the component map and THIRD_PARTY.md for the (currently empty) dependency register.