An x86 kernel written in Zig

pushedAt 2 months ago



Build Status

Pluto is a kernel written almost entirely in Zig and supports x86, with aarch64 and x64 backends being planned.

Hello image


  • Should be written in Zig as much as possible. Assembly should only be used where required for functionality or performance reasons.
  • Light and performant. The kernel should be usable both on embedded and desktop class CPUs, made possible by it being lightweight and modular.
  • Basic utilities will be written in Zig. This includes a basic text editor and shell, and will be part of the filesystem external to the kernel itself.
  • Easy to port. The kernel is oblivious to the underlying architecture, meaning that ports only need to implement the defined interface and they should work without a hitch.

All of these goals will benefit from the features of Zig.


Requires a master build of Zig at commit ad33e3483 (downloaded or built from source), xorriso and the grub tools (such as grub-mkrescue). A qemu-system binary compatible with your chosen target is required to run the kernel (e.g. qemu-system-i386).

zig build


zig build run

or if you want to wait for a gdb connection:

zig build debug-run


Launch a gdb-multiarch instance and connect to qemu.

zig build debug

Unit testing

Run the unit tests.

zig build test

Runtime testing

Run the runtime tests.

zig build rt-test -Dtest-mode=<MODE>

Available test modes:

  • None: This is the default, this will run the OS normally.
  • Initialisation: Run the OS's initialisation runtime tests to ensure the OS is properly set up.
  • Panic: Run the panic runtime test.


  • -D[build-mode]=: Boolean (default false).
    • build: Build a certain build mode (release-safe, release-fast, release-small). Don't set in order to use the debug build mode.
    • test: Test a certain build mode (release-safe, release-fast, release-small). Don't set in order to use the debug build mode.
  • -Dtarget=: String (default i386-freestanding). The standard target options for building with zig. Currently supported targets:
    • i386-freestanding
  • -Ddisable-display: Boolean (default false)
    • This disables the display output of QEMU.


We welcome all contributions, be it bug reports, feature suggestions or pull requests. We follow the style mandated by zig fmt so make sure you've run zig fmt on your code before submitting it.

We also like to order a file's members (public after non-public):

  1. imports
  2. type definitions
  3. constants
  4. variables
  5. inline functions
  6. functions
  7. entry point/init function

More styling information is available on the wiki

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