build.sh

#!/bin/sh -e

test -z "$KERNEL_DIR" -o -z "$BUILD_DIR" && {
  echo "Looks like KERNEL_DIR or BUILD_DIR is undefined"
  exit 1
}

test -d "$KERNEL_DIR" || {
  echo "KERNEL_DIR is not directory"
  exit 2
}

if [ $1 ]; then
  (
    cd "${KERNEL_DIR}" && rm -rf ./*

    kernel_ref=`curl -L https://github.com/raspberrypi/firmware/raw/$1/extra/git_hash`

    echo "Fetch kernel from https://github.com/raspberrypi/linux/tree/${kernel_ref}"

    curl -L "https://github.com/raspberrypi/linux/archive/${kernel_ref}.tar.gz" -o kernel.tar.gz
    tar -xzf kernel.tar.gz
    find . -mindepth 2 -maxdepth 2 -exec mv -t . '{}' +

    rm -rf "linux-${kernel_ref}"
    rm kernel.tar.gz
    curl -L "https://github.com/raspberrypi/firmware/raw/$1/extra/Module.symvers" -o Module.symvers
  )
fi

if [ ! "$(ls ${KERNEL_DIR})" ]; then
  echo "No kernel source found. Try to pass your firmware version tag (e.g. '1.20181112') or commit hash from https://github.com/raspberrypi/firmware repo"
  exit 3
fi

test -f "${BUILD_DIR}/.config" && {
  cp "${BUILD_DIR}/.config" "${KERNEL_DIR}"
}

cd ${KERNEL_DIR} && \
  make ARCH=arm CROSS_COMPILE=${CCPREFIX} oldconfig && \
  make ARCH=arm CROSS_COMPILE=${CCPREFIX} modules_prepare && \
  cd ${BUILD_DIR} && \
  make ARCH=arm CROSS_COMPILE=${CCPREFIX} -C ${KERNEL_DIR} M=$(pwd)