Enable Rust in the Linux kernel

Description:

Enable Rust in the kernel build for rust modules support.

Here i attached some possible changes to the config and PKGBUILD files.

This will add rustc and llvm as a makedepend.

Additional info:

• package version(s): 6.9.7.arch1-1
• it requires the rust toolchain version 1.76 as of kernel 6.9

  • it is setup automatically by running

    rustup override set $(scripts/min-tool-version.sh rustc)

    rustup component add rust-src

    cargo install --locked --version $(scripts/min-tool-version.sh bindgen) bindgen-cli

• When building, pass LLVM=1 to the make command.
• config file
  • just enable rust from nconfig
• PKGBUILD example
  • from my limited testing if make htdocs is enabled the build freezes, as of now i don't know why ("WARNING: Duplicate C declaration") but after a while it starts back. As of now i have no idea of why id does that, it must be fixed.
• Linux kernel documentation for Rust

Steps to reproduce:

1. Build the kernel with the default PKGBUILD
2. Try to load a kernel module written in Rust
3. It fails to load

added priority3-normal severity4-low statusunconfirmed labels

assigned to @freswa, @anthraxx, @toolybird, and @gromit

added scopefeature statusconfirmed labels and removed statusunconfirmed label

assigned to @heftig, @dvzrv, and @tpowa and unassigned @freswa, @toolybird, and @gromit

Hi @socket772 thank you very much for your proposal. It would be best if you can open an MR linked to your feature request for the proposal, as it is way more streamlined in GitLab land to collaborate on a change-request rather than issue attachments. Thanks.

When building, pass LLVM=1 to the make command

That builds the entire kernel with Clang. Is that really needed?

just checked, the linux documentation wasn't super clear about this. it looks like it is possible

Ok just found a paragraph that says

libclang (part of LLVM) is used by bindgen to understand the C code in the kernel, which means LLVM needs to be installed; like when the kernel is compiled with LLVM=1.

source: https://docs.kernel.org/rust/quick-start.html

I would like to wait for this patch series to land in a stable kernel: https://lore.kernel.org/rust-for-linux/20240701183625.665574-1-ojeda@kernel.org/

Then we will be able to depend on our normal rust package instead of a specific Rust just for the kernel.

I guess this will land with the release of the 6.11 series as stable kernel?

It landed in 6.11-rc1.

added statuswaiting-upstream label and removed statusconfirmed label

changed due date to July 17, 2024

removed due date July 17, 2024

added statuson-hold label and removed statuswaiting-upstream label

closed with commit 14fad3df

I saw that this was closed, but the commit then immediately reverted since it caused issues, so it can probably be reopened.

Also I wanted to add, that I'm maintaining the https://aur.archlinux.org/packages/linux-rust AUR package which basically is this kernel package with just Rust support added. So if anyone wants to discus something regarding Rust support in the kernel feel free to reach out to me

added resolutioncompleted label

Waiting for more fixes to land:

#82 (closed)
https://github.com/Rust-for-Linux/linux/issues/355

This will be fixed in 6.12:

 - Support 'MITIGATION_{RETHUNK,RETPOLINE,SLS}' (which cleans up objtool
   warnings), teach objtool about 'noreturn' Rust symbols and mimic
   '___ADDRESSABLE()' for 'module_{init,exit}'. With that, we should be
   objtool-warning-free, so enable it to run for all Rust object files.

See: https://lore.kernel.org/lkml/CAHk-=wjuMrUMceYX01T0SBz4E0yL4Kh2Jb_8qyKxJwwitCG6Zw@mail.gmail.com/T/#m2131c258ba0c7208380db06cc56561b78e3c4aab

reopened

added statuswaiting-upstream label and removed resolutioncompleted statuson-hold labels

added scopeenhancement label and removed scopefeature label

When this lands it may be worth considering enabling the new QR code panic screen (patch series).

Adding it as a note here for now.

added resolutioncompleted label

closed

mentioned in commit mcoffin/aur-linux@14fad3df