src/tests/rust-for-linux.md

# Rust for Linux integration tests

[Rust for Linux](https://rust-for-linux.com/) (RfL) is an effort for adding
support for the Rust programming language into the Linux kernel.

## Building Rust for Linux in CI

Rust for Linux builds as part of the suite of bors tests that run before a pull
request is merged.

The workflow builds a stage1 sysroot of the Rust compiler, downloads the Linux
kernel, and tries to compile several Rust for Linux drivers and examples using
this sysroot. RfL uses several unstable compiler/language features, therefore
this workflow notifies us if a given compiler change would break it.

If you are worried that a pull request might break the Rust for Linux builder
and want to test it out before submitting it to the bors queue, simply add this
line to your PR description:

> try-job: x86_64-rust-for-linux

Then when you `@bors try` it will pick the job that builds the Rust for Linux
integration.

## What to do in case of failure

If a PR breaks the Rust for Linux CI job, then:

- If the breakage was unintentional and seems spurious, then let [RfL][rfl-ping]
  know and retry.
    - If the PR is urgent and retrying doesn't fix it, then disable the CI job
      temporarily (comment out the `image: x86_64-rust-for-linux` job in
      `src/ci/github-actions/jobs.yml`).
- If the breakage was unintentional, then change the PR to resolve the breakage.
- If the breakage was intentional, then let [RfL][rfl-ping] know and discuss
  what will the kernel need to change.
    - If the PR is urgent, then disable the CI job temporarily (comment out
      the `image: x86_64-rust-for-linux` job in `src/ci/github-actions/jobs.yml`).
    - If the PR can wait a few days, then wait for RfL maintainers to provide a
      new Linux kernel commit hash with the needed changes done, and apply it to
      the PR, which would confirm the changes work (update the  `LINUX_VERSION`
      environment variable in `src/ci/docker/scripts/rfl-build.sh`).

If you need to contact the RfL developers, you can ping the [Rust for Linux][rfl-ping]
ping group to ask for help:

```text
@rustbot ping rfl
```

[rfl-ping]: ../notification-groups/rust-for-linux.md