Compiling and running a Rust kernel

Yocto 5 onward, all supported boards have now been ported to kernel 6.12. As a result, it is now possible to compile the linux kernel with Rust support for ADSP-SC598 boards.

Requirements

  • rust (installed via rustup)

  • Linux kernel source code

  • LLVM

  • clang

  • Aarch64 GCC compiler

Run the following to install the prerequisite packages on ubuntu 22.04:

sudo apt install llvm libclang-dev gcc-aarch64-linux-gnu -y

Getting started

  1. On your host/build machine, install rust via rustup

  2. Clone the Linux kernel tree you wish to use. In our case, we will use this.

  3. Once cloned, configure the kernel using either ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make menuconfig/defconfig/olddefconfig

  4. Set up the rust environment:

cd linux

Edit the following file scripts/min-tool-version.sh with the following change:

diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh
index 91c91201212c..dd09a4ed0e96 100755
--- a/scripts/min-tool-version.sh
+++ b/scripts/min-tool-version.sh
@@ -33,7 +33,7 @@ llvm)
        fi
        ;;
 rustc)
-       echo 1.78.0
+       echo 1.82.0
        ;;
 bindgen)
        echo 0.65.1

Set the package/crate versions using the script

rustup override set $(scripts/min-tool-version.sh rustc)
rustup component add rust-src
cargo install --locked bindgen-cli
export PATH=$PATH:~/.cargo/bin

Now setup the target architecture

rustup target add aarch64-unknown-linux-gnu

  1. Check if rust is now available to be compiled into the kernel:

ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make rustavailable

You should see something like this:

Rust is available!

Now, we are ready to enable Rust kernel support!

Start the kernel config with menuconfig and enable CONFIG_RUST:

General Setup
    -> Rust support

To enable a kernel rust sample, head to the following and enable the minimal example:

Kernel hacking
    -> Sample kernel code
        -> Rust samples
              -> minimal

You can select it as a built-in module and an external kernel module. For this guide, we will keep it as a built-in module.

Now compile the kernel with the following:

ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make -j$(nproc)

You should be able to see rust modules being compiled:

RUSTC L rust/core.o
EXPORTS rust/exports_core_generated.h
RUSTC P rust/libmacros.so
BINDGEN rust/bindings/bindings_generated.rs
BINDGEN rust/bindings/bindings_helpers_generated.rs
RUSTC L rust/compiler_builtins.o
RUSTC L rust/alloc.o
EXPORTS rust/exports_alloc_generated.h
CC      rust/helpers/helpers.o
EXPORTS rust/exports_helpers_generated.h
RUSTC L rust/bindings.o

Once this is done, follow the custom fitImage compilation guide here <Yocto-Linux-Kernel-development> and generate your own fitImage.

Proceed to boot into the fitImage from your preferred boot method. Once in, you should be able to spot the following in the kernel logs:

[    1.467785] virtio_rpmsg_bus virtio1: creating channel sharc-echo-cap addr 0xa2
[    1.475113] virtio_rpmsg_bus virtio1: rpmsg host is online
[    1.480488] rproc-virtio rproc-virtio.1.auto: registered virtio1 (type 7)
[    1.487253] remoteproc remoteproc1: remote processor core2-rproc is now up
[    1.802327] rust_minimal: Rust minimal sample (init)
[    1.807237] rust_minimal: Am I built-in? true
[    1.811804] NET: Registered PF_PACKET protocol family

References