103 lines
3.9 KiB
Markdown
103 lines
3.9 KiB
Markdown
# DanOS
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**Codename: Shodan**
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A very small resilient operating system.
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## Zen of DanOS:
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- Resilient Micro-Kernel Architecture.
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- Every process run in an isolated user space not kernel space.
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- Processes cannot take down the entire OS with it when they die or is killed
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- Stable public runtime library, private OS ABI.
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- Keeps a stable runtime for user space processes between OS versions (great for backwards compatibility)
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- Allows the underlying OS to be changed without effecting applications
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- Provides a boundary to enable compatibility between OS's e.g. POSIX, MUSL etc
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- Drivers are just isolated processes in user space.
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- Thin binaries that can be restarted like applications.
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- Useful during driver development.
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- Drivers can claim MMIO / ports
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- Driver resources (e.g. IRQ/Port/MMIO) claims are automatically cleaned up if the driver dies or is killed
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- Drivers can also hook into the process lifecycle to clean up or reset hardware
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- No legacy to deal with
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- Zig code uses a clean coding style (Zen of Zig)
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- Favor reading code over writing code.
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- No magic numbers.
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- No shortened names unless its for ABI compatibility or acronyms
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- Inter-Process Communication (IPC)
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- Publish and subscribe to Asynchronous Messages
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- Talk to services and processes synchronously
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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 a FHS-shaped `zig-out/` that *is* the danos filesystem and the boot volume:
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the UEFI bootloader at `zig-out/EFI/BOOT/BOOTX64.efi`, the kernel at
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`zig-out/system/kernel`, init at `zig-out/system/services/init`, drivers under
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`zig-out/system/drivers/`, and the initial-ramdisk at `zig-out/boot/`.
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## Release media
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```sh
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zig build release-x86-64
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```
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Produces `zig-out/danos-x86-64.iso`, a hybrid ISO that boots flashed raw to a
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USB stick (balenaEtcher, dd) or burned to optical media — see
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[docs/release-iso.md](docs/release-iso.md). `zig build check-iso-image`
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validates it without booting.
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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 *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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For the hardware needed to run DanOS — minimum specs plus a plain-language guide
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matching Intel/AMD CPU generations by name — see
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[`docs/system-requirements.md`](docs/system-requirements.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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