Daniel SamsonandClaude Fable 5
724de7bbd0
paging.init now builds the physmap (physToVirt(phys)) alongside the low identity map, so both addressing modes resolve during the transition. tableAt (the page-table walk hinge), the pmm bitmap, the framebuffer, LAPIC/IOAPIC/HPET/PM-timer/SPCR MMIO, the ACPI table walk, AML OperationRegions, the ACPI power registers, the user-ELF frame fills, and the AP trampoline arm/disarm all reach physical memory through the physmap. Hal.mapMmio now maps into the physmap and returns the virtual address, so the device layer never learns the layout. boot_info and its pointees are converted at kmain entry. The kernel still links and runs low; identity is the safety net until it's removed. Suite 27/27. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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.