Daniel Samson
eabb81684a
The microkernel message backbone the VFS server and drivers will ride on. - src/kernel/ipc_sync.zig: Endpoint (sender FIFO threaded via Task.next + a recv WaitQueue for servers + a small notification ring). call() (client sends, wakes a server, blocks) and replyWait() (server replies to the held caller, then receives the next). Reply routing keys on Task.ipc_client — synchronous IPC owes one reply at a time. Payloads copy frame-to-frame through the physmap (copyAcross on arch.translate, added in M5); an unmapped page fails the copy instead of #PF-ing. MSG_MAX 256. - Bootstrap naming: an integer name registry (danos.ServiceId, vfs=1) with create_endpoint / ipc_register / ipc_lookup — any process finds a server without threading a handle through spawn. - notifyFromIsr(): ISR-safe async wake (badge with the high bit set), the hook M10's IRQ-as-message needs. Unused/untested until then. - Task gains handles[16] (opaque *Endpoint, to avoid a sched<->ipc import cycle) + ipc_client/send/reply/status fields; sched gains blockCurrentLocked/readyLocked; arch gains setSyscallResult2 (rdx badge). - Syscalls 6..10 wired in process.zig; exit() now drops the caller's endpoint refs. lib/ipc.zig: user-side createEndpoint/register/lookup/call (server-side replyWait lands with the first server in M9). - New `ipc-call` test: two kernel tasks ping-pong 100 calls, every reply request+1. Suite 29/29.
DanOS
Codename: Shodan Version: 1
A small operating system, written from scratch in Zig — a bootloader (src/boot/)
and a microkernel (src/kernel/), sharing a neutral handoff contract (src/root.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.