88 lines
3.5 KiB
Markdown
88 lines
3.5 KiB
Markdown
# DanOS
|
|
Codename: Shodan
|
|
Version: 1
|
|
|
|
A small resilient operating system, written from scratch in Zig.
|
|
|
|
## Zen of DanOS:
|
|
|
|
- Resilient Micro-Kernel Architecture.
|
|
- Every process run in an isolated user space not kernel space.
|
|
- Processes cannot take down the entire OS with it when they die or is killed
|
|
- Stable public runtime library, private OS ABI.
|
|
- Keeps a stable runtime for user space processes between OS versions (great for backwards compatibility)
|
|
- Allows the underlying OS to be changed without effecting applications
|
|
- Provides a boundary to enable compatibility between OS's e.g. POSIX, MUSL etc
|
|
- Drivers are just isolated processes in user space.
|
|
- Thin binaries that can be restarted like applications.
|
|
- Useful during driver development.
|
|
- Drivers can claim MMIO / ports
|
|
- Driver resources (e.g. IRQ/Port/MMIO) claims are automatically cleaned up if the driver dies or is killed
|
|
- Drivers can also hook into the process lifecyle to clean up or reset hardware
|
|
- No legacy to deal with
|
|
- Zig code uses a clean coding style (Zen of Zig)
|
|
- Favor reading code over writing code.
|
|
- No magic numbers.
|
|
- No shortend names unless its for ABI compatibility or acronyms
|
|
- Inter-Process Communication (IPC)
|
|
- Publish and subscribe to Asynchronous Messages
|
|
- Talk to services and processes synchronously
|
|
|
|
## 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](https://github.com/tristanisham/zvm)
|
|
or `zigup` will pick up `.zig-version` automatically.
|
|
- **QEMU** (`qemu-system-x86_64`) — to run and test the kernel. On macOS,
|
|
`brew install qemu` also bundles the OVMF firmware below.
|
|
- **OVMF** UEFI firmware — the `edk2-ovmf` package (Arch), `ovmf` (Debian/Ubuntu),
|
|
or `edk2-ovmf` (Fedora); on macOS it ships inside the Homebrew `qemu` formula.
|
|
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
|
|
|
|
```sh
|
|
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):
|
|
|
|
```sh
|
|
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
|
|
|
|
```sh
|
|
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 *why* behind the code live in
|
|
[`docs/`](docs/README.md) — start with [`docs/README.md`](docs/README.md).
|
|
|
|
## Logo
|
|
|
|
San Serif Text "Dan OS" with a black karate belt around it.
|