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Daniel Samson 37326c7664 C5: delete the runtime.zig and system.zig compatibility shims With every consumer migrated (C2), nothing imports `runtime` or `system` any longer. Removed both shim files and their build.zig module definitions, dropped the `runtime` entry from `default_imports`, and rewrote the per-binary root shim (library/kernel/root.zig) to import `start` (_start + panic) and `logging` (std_options) directly instead of through `runtime`. addUserBinary/addThreadedUserBinary/addUserBinaryImpl lose their `runtime_module` parameter; the root module now pulls the two modules it needs out of `default_imports` via a small findImport helper. The runtime dumping ground is gone: the userspace library is library/kernel (concern modules), library/device (driver/pci/usb/block/model/mmio/acpi data), library/client (display, input service clients), and library/protocol (wire contracts). Consumers @import concern modules by name. Verified: zig build, zig build test, and QEMU (smoke, thread-spawn, thread-mutex, logger, display-native, device-manager, usb-storage, input).		2026-07-22 23:32:05 +01:00
boot	boot: the capsule — one-file system image first, manifest and walk as fallbacks	2026-07-21 18:57:33 +01:00
docs	kernel: flatten the device/discovery code, merge power into acpi, rename fdt	2026-07-22 21:49:20 +01:00
library	C5: delete the runtime.zig and system.zig compatibility shims	2026-07-22 23:32:05 +01:00
system	C2: migrate consumers off the runtime shim to direct concern-module imports	2026-07-22 23:28:34 +01:00
test	kernel+tests: M4 shared-fate — nine group-death test cases, per-space arena cursors	2026-07-22 10:49:46 +01:00
tools	boot: the capsule — one-file system image first, manifest and walk as fallbacks	2026-07-21 18:57:33 +01:00
usr/share/fonts	assets: add font families under usr/share/fonts	2026-07-14 18:39:23 +01:00
.editorconfig	editorconfig	2026-07-12 16:09:11 +01:00
.gitattributes	gitattributes	2026-07-12 16:09:18 +01:00
.gitignore	gitignore: /var/log — real-hardware log pulls stay out of the tree	2026-07-21 20:09:29 +01:00
README.md	update README.md	2026-07-20 13:39:03 +01:00
build.zig	C5: delete the runtime.zig and system.zig compatibility shims	2026-07-22 23:32:05 +01:00
build.zig.zon	started project with basic efi setup	2026-07-01 18:32:56 +01:00

README.md

DanOS

Codename: Shodan

A very small resilient operating system.

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 lifecycle 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 shortened 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 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

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/.

Release media

zig build release-x86-64

Produces zig-out/danos-x86-64.iso, a hybrid ISO that boots flashed raw to a USB stick (balenaEtcher, dd) or burned to optical media — see docs/release-iso.md. zig build check-iso-image validates it without booting.

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 why behind the code live in docs/ — start with docs/README.md.

For the hardware needed to run DanOS — minimum specs plus a plain-language guide matching Intel/AMD CPU generations by name — see docs/system-requirements.md.

Logo

San Serif Text "Dan OS" with a black karate belt around it.