Test OS

A useless OS in Rust

Building

Prerequisites

• Recent nightly Rust toolchain with the rust-src component
• Recent nightly Cargo
• Xorriso to generate bootable ISOs (currently the only way to run testos)

For Rust, see https://rustup.rs/ or use your system package manager. For Xorriso, use your system package manager (not sure how to get it on Windows).

Build

Use the following commands:

• cargo kimage: builds the bootable ISO.
• cargo kcheck: runs cargo check on the kernel source.
• cargo kclippy: runs cargo clippy on the kernel source.
• cargo scheck & cargo sclippy: equivalents for code in shared.
• cargo stest: run unit tests in shared.

.cargo/config.toml defines the aliases above.

Run

QEMU is the main supported way to run testos. It is currently not tested on real hardware. After running cargo mkimage you can run it with

qemu-system-x86_64 -cdrom out/kernel.iso

Project structure

The project is organized into multiple packages in a Cargo workspace. The main package (whose source is in src) is the kernel itself. The sub-packages are:

• shared: Standalone types and helpers that don't need to be run in kernel space. This was originally called "shared" because a previous iteration had an intermediate bootloader that had to be compiled separately. Now it's only separate to make it easier to run unit tests.
• mkimage: Builds a bootable ISO from the built kernel using GRUB and xorriso.
• buildutil: Helpers shared between build scripts and mkimage.

targets contains target specifications passed to rustc. Currently there is only one: x86_64-unknown-none.json. This is necessary to target bare-metal x86.

out contains output artifacts, including the bootable kernel.iso.

A prebuilt GRUB image is located in third_party.