Daniel Samson
4ef21fa083
Two parts, both blockers for real PCI drivers. ECAM config space per function: enumeratePci now gives every pci_device its own 4 KiB configuration window as resource 0. A claimed PCI driver mmio_maps that to reach its command register, BARs, and — the point — its capability list (MSI/MSI-X, PCIe extended caps), with no new syscall. Verified in the discovery test (QEMU q35's functions each carry it). MSI: msi_bind(device_id, endpoint) -> address (rax), data (rdx) allocates a per-device edge-triggered vector, binds it to the endpoint, and returns the (address, data) the driver programs into its own MSI capability. Unlike irq_bind there's no GSI, no I/O APIC entry, no sharing, and no ack cycle — dispatch recognises an MSI vector (vector_gsi == none, msi_bound set), EOIs, and notifies. Owner-keyed release drops the binding on exit. Legacy INTx (_PRT parsing + shared lines) is deliberately skipped; MSI is the real answer. QEMU's HPET has no MSI, so the new `msi` test proves the vector-routing path with a self-IPI (new apic.selfIpi) standing in for the device's MSI write: bind a vector, fire it, the bound endpoint is notified. The msi_bind syscall wraps irq.msiBind with the claim check and lands its first real use with the first PCI driver. Suite 39/39 plus host tests.
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/boot-handoff.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 a FHS-shaped zig-out/ that is the danos filesystem and the boot volume:
the UEFI bootloader at zig-out/EFI/BOOT/BOOTX64.efi, the kernel at
zig-out/system/kernel, init at zig-out/system/services/init, drivers under
zig-out/system/drivers/, and the initial-ramdisk at zig-out/boot/.
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.