kernel.yml

name: Compile Linux Kernel
on:
  workflow_dispatch:
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - name: Set up dependencies
      run: |
        sudo apt-get update
        sudo apt-get install -y llvm lld clang clang-tools libelf-dev
    - name: Compile Busybox
      run: |
        BUSYBOX_VERSION=1.36.1
        docker run --rm -v $PWD/busybox:/busybox-${BUSYBOX_VERSION} archlinux env BUSYBOX_VERSION=${BUSYBOX_VERSION} sh -c "
          pacman-key --init
          pacman -Syu --noconfirm base-devel musl kernel-headers-musl
          curl https://busybox.net/downloads/busybox-${BUSYBOX_VERSION}.tar.bz2 | tar -jx
          cd busybox-${BUSYBOX_VERSION}
          make defconfig -j$(nproc)
          LDFLAGS="--static" KCONFIG_NOTIMESTAMP=1 make CC=musl-gcc -j$(nproc)
        "
    - name: Generate initramfs
      run: |
        mkdir rootfs
        pushd rootfs
        mkdir -p bin dev/{pts,shm} proc sys tmp
        cp ../busybox/busybox bin
        for i in $(./bin/busybox --list);do
          ln -sf busybox bin/$i
        done
        cat > init << EOF
        #!/bin/sh
        mount -t devtmpfs dev /dev
        mount -t proc proc /proc
        mount -t sysfs sys /sys
        mount -t tmpfs tmpfs /tmp
        mount -t devpts devpts /dev/pts
        mount -t tmpfs tmpfs /dev/shm
        setsid cttyhack /bin/sh
        EOF
        chmod +x init
        find . -print0 | cpio -o --format=newc -0 -R 0:0 > ../rootfs.cpio
        popd
    - name: Compile Kernel
      run: |
        KERNEL_VERSION=6.6.69
        curl https://cdn.kernel.org/pub/linux/kernel/v${KERNEL_VERSION%%.*}.x/linux-${KERNEL_VERSION}.tar.xz | tar -Jx
        pushd linux-${KERNEL_VERSION}
        make LLVM=1 defconfig
        sed -i 's|.*CONFIG_INITRAMFS_SOURCE="".*|CONFIG_INITRAMFS_SOURCE="rootfs.cpio"|' .config
        sed -i "s|.*\\(CONFIG_KERNEL_.*\\)=y|\\#\\ \\1 is not set|" .config
        sed -i "s|.*# CONFIG_KERNEL_XZ is not set.*|CONFIG_KERNEL_XZ=y|" .config
        sed -i "s|^CONFIG_DEBUG_KERNEL.*|# CONFIG_DEBUG_KERNEL is not set|" .config
        sed -i "s|.*CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE=y.*|# CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE is not set|" .config
        sed -i "s|.*# CONFIG_CC_OPTIMIZE_FOR_SIZE is not set.*|CONFIG_CC_OPTIMIZE_FOR_SIZE=y|" .config
        sed -i "s|.*CONFIG_AUDIT=y.*|# CONFIG_AUDIT is not set|" .config
        sed -i "s|.*CONFIG_FTRACE=y.*|# CONFIG_FTRACE is not set|" .config
        sed -i "s|.*CONFIG_FB_VESA.*|CONFIG_FB_VESA=y|" .config
        cp ../rootfs.cpio .
        make LLVM=1 -j$(nproc)
        cp arch/x86/boot/bzImage ../vmlinuz
        popd
    - run: du -k vmlinuz
    - name: Upload artifact
      uses: actions/upload-artifact@v4
      with:
        name: vmlinuz
        path: vmlinuz