Daniel Samson
ceacc6b514
Follow-up to the monorepo re-org. Suite 35/35 plus host tests green. POSIX compatibility is now its own library, library/posix/ (unistd, stdio), layered strictly over the runtime — it calls the runtime's IPC/heap, never system calls directly. The runtime is now POSIX-free (the danos-native application ABI). The VFS wire protocol is danos-native throughout (Stat -> FileStatus, .stat -> .status, O_CREAT -> create); the POSIX layer maps the POSIX spellings at the boundary. The coding standard's ABI-name exception is scoped to one place: a file is allowed POSIX spellings only if it lives under library/posix/ — everywhere else, danos naming with no exception. Naming fixes, all mechanical: - initrd -> initial-ramdisk: the source file, the module, the tool (make-initial-ramdisk.py), the artifact (initial-ramdisk.img, including the bootloader's load path), and the identifiers. - system/kernel/device-service.zig -> devices-broker.zig: it is ring-0 kernel code (the trusted device table + claim capability), not a ring-3 service. The future user-space device *manager* (policy) will live in system/services/. - Dropped the daemon `d` suffix: hpetd -> hpet, busd -> bus. A driver lives in system/drivers/, so the folder already says what it is; encoding the role in the name too is redundant. The coding standard drops that exception. - system/devices/aml/interp.zig -> interpreter.zig (the type was already Interpreter).
DanOS
Codename: Shodan Version: 1
A small operating system, written from scratch in Zig — a bootloader (boot/)
and a microkernel (system/kernel/), sharing a neutral handoff contract (system/danos.zig).
It boots x86-64 via UEFI, and so far has a framebuffer console, a physical frame
allocator, its own paging with W^X permissions, interrupt/exception handling, a
LAPIC timer, a kernel heap, a fixed-priority preemptive scheduler, and in-kernel IPC
channels. See docs/ for how each piece works.
Prerequisites
- Zig 0.16.x — the build is pinned to this line (
.zig-version); other minor versions are rejected, because Zig makes breaking changes between releases pre-1.0. A toolchain manager such as zvm orzigupwill pick up.zig-versionautomatically. - QEMU (
qemu-system-x86_64) — to run and test the kernel. On macOS,brew install qemualso bundles the OVMF firmware below. - OVMF UEFI firmware — the
edk2-ovmfpackage (Arch),ovmf(Debian/Ubuntu), oredk2-ovmf(Fedora); on macOS it ships inside the Homebrewqemuformula. Both the build and the test harness probe the known Arch/Debian/Fedora/macOS layouts and use the first that exists, so no configuration is normally needed. Override with-Dovmf-code=/-Dovmf-vars=(build) if yours lives elsewhere. - Python 3 — for the QEMU integration test harness.
Build
zig build
Produces the UEFI bootloader (zig-out/bin/BOOTX64.efi) and the kernel ELF
(zig-out/bin/kernel).
Run
Boot it in QEMU with OVMF (opens a display window):
zig build run-x86-64
# distro with OVMF elsewhere:
zig build run-x86-64 -Dovmf-code=/path/OVMF_CODE.fd -Dovmf-vars=/path/OVMF_VARS.fd
Test
zig build test # host unit tests (the platform-independent shared code)
python3 test/qemu_test.py # QEMU integration tests: boots the kernel and asserts
# on its serial output (see docs/testing.md)
The integration harness builds and boots the kernel once per test case, checking memory, the frame allocator, paging (incl. NX and the null guard), the heap, interrupts, and exception handling. It exits non-zero on any failure, so it drops straight into CI.
Documentation
Design notes explaining the why behind the code live in
docs/ — start with docs/README.md.
Logo
San Serif Text "Dan OS" with a black karate belt around it.