Daniel Samson
8754d4e46a
The source layout now mirrors the runtime filesystem hierarchy
(docs/danos-file-system-hierarchy-FSH.md): what lives under system/ in the
source is what a running danos represents under /system. Each service and
driver is a sub-project directory that is its own Zig module — cross-project
references go by module name, never by a path into another project's files.
Moves (all git mv, history preserved):
- src/ -> system/ (danos internals; the self-representation)
root.zig -> danos.zig (the kernel<->user contract module)
kernel/arch/ -> kernel/architecture/ (arch -> architecture)
device/ -> devices/ (what /system/devices reflects)
boot/ -> /boot (the loaders, top level)
- sbin/ -> split by role:
init, vfs -> system/services/<name>/<name>.zig
hpetd, busd -> system/drivers/<name>/<name>.zig
vfs-test -> system/services/vfs/vfs-test.zig (inside the vfs project)
- lib/ -> library/runtime/ (room for other libraries beside runtime)
The VFS wire protocol becomes its own module, system/services/vfs/protocol.zig
("vfs-protocol"): the vfs sub-project exposes its interface, and the runtime's
file layer imports it by name. First instance of the "protocol module" pattern
(docs/driver-model.md); usb/block will expose theirs the same way.
Also: fix a naming-standard violation in the protocol — Op -> Operation (and
req -> request, _pad -> _padding). Docs updated: /system/services added to the
FHS doc, a repository-layout section added to the docs index, and stale source
paths swept across comments and docs.
Runtime boot paths are unchanged (the bootloader still loads /sbin/init);
aligning the runtime filesystem to the FHS is a separate follow-up. Suite 35/35
plus host tests green.
67 lines
2.5 KiB
Markdown
67 lines
2.5 KiB
Markdown
# DanOS
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Codename: Shodan
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Version: 1
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A small operating system, written from scratch in Zig — a bootloader (`boot/`)
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and a microkernel (`system/kernel/`), sharing a neutral handoff contract (`system/danos.zig`).
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It boots x86-64 via UEFI, and so far has a framebuffer console, a physical frame
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allocator, its own paging with W^X permissions, interrupt/exception handling, a
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LAPIC timer, a kernel heap, a fixed-priority preemptive scheduler, and in-kernel IPC
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channels. See [`docs/`](docs/README.md) for how each piece works.
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## Prerequisites
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- **Zig 0.16.x** — the build is pinned to this line (`.zig-version`); other minor
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versions are rejected, because Zig makes breaking changes between releases
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pre-1.0. A toolchain manager such as [zvm](https://github.com/tristanisham/zvm)
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or `zigup` will pick up `.zig-version` automatically.
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- **QEMU** (`qemu-system-x86_64`) — to run and test the kernel. On macOS,
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`brew install qemu` also bundles the OVMF firmware below.
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- **OVMF** UEFI firmware — the `edk2-ovmf` package (Arch), `ovmf` (Debian/Ubuntu),
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or `edk2-ovmf` (Fedora); on macOS it ships inside the Homebrew `qemu` formula.
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Both the build and the test harness probe the known Arch/Debian/Fedora/macOS
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layouts and use the first that exists, so no configuration is normally needed.
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Override with `-Dovmf-code=` / `-Dovmf-vars=` (build) if yours lives elsewhere.
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- **Python 3** — for the QEMU integration test harness.
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## Build
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```sh
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zig build
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```
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Produces the UEFI bootloader (`zig-out/bin/BOOTX64.efi`) and the kernel ELF
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(`zig-out/bin/kernel`).
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## Run
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Boot it in QEMU with OVMF (opens a display window):
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```sh
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zig build run-x86-64
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# distro with OVMF elsewhere:
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zig build run-x86-64 -Dovmf-code=/path/OVMF_CODE.fd -Dovmf-vars=/path/OVMF_VARS.fd
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```
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## Test
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```sh
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zig build test # host unit tests (the platform-independent shared code)
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python3 test/qemu_test.py # QEMU integration tests: boots the kernel and asserts
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# on its serial output (see docs/testing.md)
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```
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The integration harness builds and boots the kernel once per test case, checking
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memory, the frame allocator, paging (incl. NX and the null guard), the heap,
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interrupts, and exception handling. It exits non-zero on any failure, so it drops
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straight into CI.
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## Documentation
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Design notes explaining the *why* behind the code live in
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[`docs/`](docs/README.md) — start with [`docs/README.md`](docs/README.md).
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## Logo
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San Serif Text "Dan OS" with a black karate belt around it.
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