build-kernel.sh

#!/bin/sh
#
# A small script used to rebuild the BlissOS kernel image
# Shamelessly stol.. "inspired by" prebuilts/qemu-kernel/build-kernel.sh
#

CMD=$1

if [ -z "$ANDROID_BUILD_TOP" ]; then
    echo "ERROR: You must have run lunch in the top level android source directory to run this script."
    exit 1
fi

# TODO(dubielm): We have to decide if we want per family or per product builds
# and then we should be able to use TARGET_PRODUCT directly.
BUILD_FAMILY_NAME=$(basename $ANDROID_PRODUCT_OUT)

OUTPUT=$ANDROID_BUILD_TOP/device/google/desktop/${BUILD_FAMILY_NAME}-kernels/6.6

# TODO: b/379702641 - Once we are firmly building brya kernels via Kleaf,
# upgrade this warning to a harder stop requiring user confirmation.
if [ $BUILD_FAMILY_NAME = "brya" ]; then
  echo "WARNING: Brya devices are migrating to Kleaf-based kernel prebuilts."
  echo "This script is still OK to use for now, but be warned that this script"
  echo "will soon be deprecated for Brya."
  echo "Instructions for building via Kleaf will be available at that time."

  # Update brya path to include legacy_kernel suffix.
  OUTPUT=$OUTPUT/legacy_kernel
fi

# Determine the host architecture, and which default prebuilt tag we need.
# For the toolchain auto-detection.
#
HOST_OS=`uname -s`
case "$HOST_OS" in
    Linux)
        # note that building  32-bit binaries on x86_64 is handled later
        HOST_OS=linux
        HOST_TAG=linux-x86
        BUILD_NUM_CPUS=$(grep -c processor /proc/cpuinfo)
        ;;
    *)
        echo "ERROR: Unsupported OS: $HOST_OS"
        exit 1
esac

if [ ! -f include/linux/vermagic.h ]; then
    echo "ERROR: You must be in the top-level kernel source directory to run this script."
    exit 1
fi

# Extract kernel version, we'll need to put this in the final binaries names
# to ensure the emulator can trivially know it without probing the binary with
# 'file' or other unreliable heuristics.
KERNEL_MAJOR=$(awk '$1 == "VERSION" { print $3; }' Makefile)
KERNEL_MINOR=$(awk '$1 == "PATCHLEVEL" { print $3; }' Makefile)
KERNEL_PATCH=$(awk '$1 == "SUBLEVEL" { print $3; }' Makefile)
KERNEL_VERSION="$KERNEL_MAJOR.$KERNEL_MINOR.$KERNEL_PATCH"
echo "Found kernel version: $KERNEL_VERSION"

# Ensure output dir exists, create if necessary
mkdir -p $OUTPUT

ZIMAGE=zImage

ARCH=$($ANDROID_BUILD_TOP/build/soong/soong_ui.bash --dumpvar-mode TARGET_ARCH)
case $ARCH in
    x86|x86_64)
        ZIMAGE=bzImage
        CONFIG=android-x86_64
        ;;
    arm64)
        ZIMAGE=Image
        CONFIG=android-arm64
        ;;
    mips)
        ZIMAGE=
        ;;
    mips64)
        ZIMAGE=
        ;;
esac

export LLVM=1
PATH=$ANDROID_BUILD_TOP/prebuilts/clang/host/$HOST_TAG/clang-r530567/bin/:$PATH
export ARCH

case $CONFIG in
    defconfig)
        MAKE_DEFCONFIG=$CONFIG
        ;;
    *)
        MAKE_DEFCONFIG=${CONFIG}_defconfig
        ;;
esac

# Temp dir to hold the installed modules, auto-removed on exit
TMP_MODULES="$(mktemp -d)"
trap 'rm -rf -- "$TMP_MODULES"' EXIT

if [[ "$CMD" == "menuconfig" ]] || [[ "$CMD" == "savedefconfig" ]]; then
    make -j $BUILD_NUM_CPUS $CMD
    exit
fi

if [ "$ARCH" == "arm64" ] ; then
    # Remove all previous DTBs. This resolves the situation where the DTS
    # is removed in the new kernel. Without removing all artifacts, the FIT
    # image crated later would contain the old DTB taken from previous
    # build.
    DEVICETREES=$(find ./arch/arm64/boot/dts -name \*$BUILD_FAMILY_NAME\*.dtb)
    DEVICETREE_ARTIFACTS=$(find ./arch/arm64/boot/dts -name \*$BUILD_FAMILY_NAME\*.dtb.\*)
    rm -rf $DEVICETREES $DEVICETREE_ARTIFACTS
    # XXX: Under arm64 arch, in a later step we replace kernel image with a FIT
    # image, which extends the kernel with devices trees. Running the script
    # twice results in nested FIT FIT image, which does not boot. Hence, we
    # remove it before building.
    rm -rf arch/$ARCH/boot/$ZIMAGE
fi
# Do the build
#
rm -f include/asm &&
make -j $BUILD_NUM_CPUS $MAKE_DEFCONFIG &&                              # configure the kernel
make -j $BUILD_NUM_CPUS &&                                              # build the kernel
make -j $BUILD_NUM_CPUS modules_install INSTALL_MOD_PATH=$TMP_MODULES   # install kernel modules

if [ $? != 0 ] ; then
    echo "Could not build the kernel. Aborting !"
    exit 1
fi

if [ "$ARCH" == "arm64" ] ; then
    # replace kernel image with a FIT image which contains the kernel image, plus relevant
    # devicetrees for this build family.
    # TODO(svenva@) generate-its-script.sh is really old and generates a legacy FIT.
    #               upgrade to modern FIT format which is much more compact.
    DEVICETREES=$(find ./arch/arm64/boot/dts -name \*$BUILD_FAMILY_NAME\*.dtb)
    ./chromeos/scripts/generate-its-script.sh -a arm64 -c lz4 -d $(pwd) arch/$ARCH/boot/$ZIMAGE \
        $DEVICETREES | dtc -I dts -O dtb -p 1024 > arch/$ARCH/boot/$ZIMAGE.fit
    mv arch/$ARCH/boot/$ZIMAGE.fit arch/$ARCH/boot/$ZIMAGE
fi

# Copy over the built artifacts
# Clean module destination dir before copying, to prevent stale
# modules from getting left behind.
#
cp -f arch/$ARCH/boot/$ZIMAGE $OUTPUT/ &&
rm -f "${OUTPUT}/vendor_dlkm/"* &&
find $TMP_MODULES/lib/modules/$(cat include/config/kernel.release)/kernel/ \
    -type f -print0 | xargs -0 -I {} cp {} "$OUTPUT/vendor_dlkm/"

if [ $? != 0 ] ; then
    echo "Could not copy the kernel artifacts. Aborting !"
    exit 1
fi

echo "Kernel $CONFIG prebuilt images ($ZIMAGE and modules) copied to $OUTPUT successfully !"


exit 0