CI: add Rust for Linux auto job

src/ci/docker/host-x86_64/rfl/Dockerfile

@@ -0,0 +1,40 @@
+FROM ubuntu:22.04
+
+ARG DEBIAN_FRONTEND=noninteractive
+
+# libclang1 is required for libclang.so, required by bindgen
+# clang, llvm and lld is required by RfL to compile host code
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  g++ \
+  make \
+  ninja-build \
+  file \
+  curl \
+  ca-certificates \
+  python3 \
+  git \
+  cmake \
+  flex \
+  bison \
+  bc \
+  clang-15 \
+  libclang1-15 \
+  llvm-15 \
+  lld-15 \
+  libelf-dev \
+  libedit-dev \
+  libssl-dev \
+  pkg-config \
+  zlib1g-dev \
+  && rm -rf /var/lib/apt/lists/*
+
+COPY scripts/sccache.sh /scripts/
+RUN sh /scripts/sccache.sh
+
+# RfL needs access to cland, lld and llvm tools
+ENV PATH="${PATH}:/usr/lib/llvm-15/bin"
+
+ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu
+
+COPY /scripts/rfl-build.sh /tmp/rfl-build.sh
+ENV SCRIPT bash /tmp/rfl-build.sh

src/ci/docker/scripts/rfl-build.sh

@@ -0,0 +1,68 @@
+#!/bin/bash
+
+set -euo pipefail
+
+LINUX_VERSION=c13320499ba0efd93174ef6462ae8a7a2933f6e7
+
+# Build rustc, rustdoc and cargo
+../x.py build --stage 1 library rustdoc
+../x.py build --stage 0 cargo
+
+# Install rustup so that we can use the built toolchain easily, and also
+# install bindgen in an easy way.
+curl --proto '=https' --tlsv1.2 -sSf -o rustup.sh https://sh.rustup.rs
+sh rustup.sh -y --default-toolchain none
+
+source /cargo/env
+
+BUILD_DIR=$(realpath ./build)
+rustup toolchain link local "${BUILD_DIR}"/x86_64-unknown-linux-gnu/stage1
+rustup default local
+
+mkdir -p rfl
+cd rfl
+
+# Remove existing directory to make local builds easier
+rm -rf linux || true
+
+# Download Linux at a specific commit
+mkdir -p linux
+git -C linux init
+git -C linux remote add origin https://github.com/torvalds/linux.git
+git -C linux fetch --depth 1 origin ${LINUX_VERSION}
+git -C linux checkout FETCH_HEAD
+
+# Install bindgen
+"${BUILD_DIR}"/x86_64-unknown-linux-gnu/stage0/bin/cargo install \
+  --version $(linux/scripts/min-tool-version.sh bindgen) \
+  bindgen-cli
+
+# Configure Rust for Linux
+cat <<EOF > linux/kernel/configs/rfl-for-rust-ci.config
+# CONFIG_WERROR is not set
+
+CONFIG_RUST=y
+
+CONFIG_SAMPLES=y
+CONFIG_SAMPLES_RUST=y
+
+CONFIG_SAMPLE_RUST_MINIMAL=m
+CONFIG_SAMPLE_RUST_PRINT=y
+
+CONFIG_RUST_PHYLIB_ABSTRACTIONS=y
+CONFIG_AX88796B_PHY=y
+CONFIG_AX88796B_RUST_PHY=y
+
+CONFIG_KUNIT=y
+CONFIG_RUST_KERNEL_DOCTESTS=y
+EOF
+
+make -C linux LLVM=1 -j$(($(nproc) + 1)) \
+    rustavailable \
+    defconfig \
+    rfl-for-rust-ci.config
+
+make -C linux LLVM=1 -j$(($(nproc) + 1)) \
+    samples/rust/rust_minimal.o \
+    samples/rust/rust_print.o \
+    drivers/net/phy/ax88796b_rust.o

src/ci/github-actions/jobs.yml

@@ -465,3 +465,8 @@ auto:
       RUST_CONFIGURE_ARGS: --build=x86_64-pc-windows-msvc --enable-extended --enable-profiler
       SCRIPT: python x.py dist bootstrap --include-default-paths
     <<: *job-windows-8c
+
+  # Tests integration with Rust for Linux.
+  # Builds stage 1 compiler and tries to compile a few RfL examples with it.
+  - image: rfl
+    <<: *job-linux-8c