build_kernel.sh

#!/bin/bash
################################################################################
#
#  build_kernel.sh
#
#  Copyright (c) 2016-2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
################################################################################

################################################################################
#
#  I N P U T
#
################################################################################
# Folder for platform tarball.
PLATFORM_TARBALL="${1}"

# Target directory for output artifacts.
TARGET_DIR="${2}"

################################################################################
#
#  V A R I A B L E S
#
################################################################################

# Retrieve the directory where the script is currently held
SCRIPT_BASE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

# Configuration file for the build.
CONFIG_FILE="${SCRIPT_BASE_DIR}/build_kernel_config.sh"

# Prebuilts include folder
PREBUILTS_FOLDER="${SCRIPT_BASE_DIR}/prebuilt"

# Workspace directory & relevant temp folders.
WORKSPACE_DIR="$(mktemp -d)"

TOOLCHAIN_DIR="${WORKSPACE_DIR}/toolchain"
PLATFORM_EXTRACT_DIR="${WORKSPACE_DIR}/src"
WORKSPACE_OUT_DIR="${WORKSPACE_DIR}/out"

for d in "${TOOLCHAIN_DIR}" "${PLATFORM_EXTRACT_DIR}" "$WORKSPACE_OUT_DIR"
do
    mkdir -p "${d}"
done

# Remove workspace directory upon completion.
trap "rm -rf $WORKSPACE_DIR" EXIT

PARALLEL_EXECUTION="-j8"

function usage {
    echo "Usage: ${BASH_SOURCE[0]} path_to_platform_tar output_folder" 1>&2
    exit 1
}

function validate_input_params {
    if [[ ! -f "${PLATFORM_TARBALL}" ]]
    then
        echo "ERROR: Platform tarball not found."
        usage
    fi

    if [[ ! -f "${CONFIG_FILE}" ]]
    then
        echo "ERROR: Could not find config file ${CONFIG_FILE}. Please check" \
             "that you have extracted the build script properly and try again."
        usage
    fi

    if [[ ! -d "${PREBUILTS_FOLDER}" ]]
    then
        echo "ERROR: Missing prebuilts folder ${PREBUILTS_FOLDER}"
        usage
    fi
}

function validate_cross_compiler {
    if [[ ! -d "${CROSS_COMPILER_PATH}" || \
		! -d "${CROSS_COMPILER_PATH}/bin" ]]
    then
	echo "ERROR: Invalid or missing path to cross compiler" \
	     "${CROSS_COMPILER_PATH}.  Please check and update" \
	     "build_kernel_config.sh"
	usage
    fi
}

function display_config {
    echo "-------------------------------------------------------------------------"
    echo "SOURCE TARBALL: ${PLATFORM_TARBALL}"
    echo "TARGET DIRECTORY: ${TARGET_DIR}"
    echo "KERNEL SUBPATH: ${KERNEL_SUBPATH}"
    echo "DEFINITION CONFIG: ${DEFCONFIG_NAME}"
    echo "TARGET ARCHITECTURE: ${TARGET_ARCH}"
    echo "CROSS COMPILER PATH: ${CROSS_COMPILER_PATH}"
    echo "TOOLCHAIN REPO: ${TOOLCHAIN_REPO}"
    echo "TOOLCHAIN PREFIX: ${TOOLCHAIN_PREFIX}"
    echo "-------------------------------------------------------------------------"
    echo "Sleeping 3 seconds before continuing."
    sleep 3
}

function setup_output_dir {
    if [[ -d "${TARGET_DIR}" ]]
    then
        FILECOUNT=$(find "${TARGET_DIR}" -type f | wc -l)
        if [[ ${FILECOUNT} -gt 0 ]]
        then
            echo "ERROR: Destination folder is not empty. Refusing to build" \
                 "to a non-clean target"
            exit 3
        fi
    else
        echo "Making target directory ${TARGET_DIR}"
        mkdir -p "${TARGET_DIR}"

        if [[ $? -ne 0 ]]
        then
            echo "ERROR: Could not make target directory ${TARGET_DIR}"
            exit 1
        fi
    fi
}

function download_toolchain {
    echo "Cloning toolchain ${TOOLCHAIN_REPO} to ${TOOLCHAIN_DIR}"
    git clone  -b pie-release "${TOOLCHAIN_REPO}" "${TOOLCHAIN_DIR}"
    if [[ $? -ne 0 ]]
    then
        echo "ERROR: Could not clone toolchain from ${TOOLCHAIN_REPO}."
        exit 2
    fi
}

function extract_tarball {
    echo "Extracting tarball to ${PLATFORM_EXTRACT_DIR}"
    tar xf "${PLATFORM_TARBALL}" -C ${PLATFORM_EXTRACT_DIR}
}

function exec_build_kernel {
    CCOMPILE="${CROSS_COMPILER_PATH}/bin/${TOOLCHAIN_PREFIX}"

    if [[ -n "${KERNEL_SUBPATH}" ]]
    then
        MAKE_ARGS="-C ${KERNEL_SUBPATH}"
    fi

    MAKE_ARGS="${MAKE_ARGS} O=${WORKSPACE_OUT_DIR} ARCH=${TARGET_ARCH} CROSS_COMPILE=${CCOMPILE}"
    echo "Base make args: ${MAKE_ARGS}"

    # Move into the build base folder.
    pushd "${PLATFORM_EXTRACT_DIR}"

    # Step 1: defconfig
    echo "Make defconfig: make ${MAKE_ARGS} ${DEFCONFIG_NAME}"
    make ${MAKE_ARGS} ${DEFCONFIG_NAME}

    # Step 2: check trapz:
    local KERNEL_FOLDER="${PLATFORM_EXTRACT_DIR}/${KERNEL_SUBPATH}"
    local TRAPZ_CFG="${KERNEL_FOLDER}/arch/${TARGET_ARCH}/configs/trapz.config"
    local OUTPUT_CFG="${WORKSPACE_OUT_DIR}/.config"

    if [[ -f $TRAPZ_CFG ]]
    then
        echo "Adding trapz config to config"
        cat "${TRAPZ_CFG}" >> "${OUTPUT_CFG}"
    else
        echo "No trapz config found."
    fi

    # Step 3: run oldconfig
    echo "Make oldconfig: make ${MAKE_ARGS} oldconfig"
    make ${MAKE_ARGS} oldconfig

    # Step 3A: output config, for reference
    echo ".config contents"
    echo "---------------------------------------------------------------------"
    cat "${OUTPUT_CFG}"
    echo "---------------------------------------------------------------------"

    # Step 4: Make headers install
    echo "Make headers install: make ${MAKE_ARGS} headers_install"
    make ${MAKE_ARGS} headers_install

    # Step 5: install prebuilt headers
    if [[ -d "${PREBUILTS_FOLDER}" ]]
    then
        echo "Copying prebuilts to ${WORKSPACE_OUT_DIR}"
        cp -av ${PREBUILTS_FOLDER}/* "${WORKSPACE_OUT_DIR}"
    fi

    # Step 6: dtbs
    if [[ -n "${MAKE_DTBS}" ]]
    then
        echo "Make dtbs: make ${MAKE_ARGS} dtbs"
        make ${MAKE_ARGS} dtbs
    fi

    # Step 7: full make
    echo "Running full make"
    if [[ -n "${ZIMAGE_TARGET}" ]]
    then
        make ${MAKE_ARGS} ${PARALLEL_EXECUTION} USE_TRAPZ=true zImage
    else
        make ${MAKE_ARGS} ${PARALLEL_EXECUTION} USE_TRAPZ=true
    fi

    if [[ $? -ne 0 ]]
    then
        echo "Build failed"
        exit 10
    fi

    popd
}

function copy_to_output {
    echo "Copying files to output"

    pushd "${WORKSPACE_OUT_DIR}"
    find "./arch/"${TARGET_ARCH}"/boot" -type f | sed 's/^\.\///' | while read CPFILE
    do
        local BASEDIR="$(dirname "${CPFILE}")"
        if [[ ! -d "${TARGET_DIR}/${BASEDIR}" ]]
        then
            mkdir -p "${TARGET_DIR}/${BASEDIR}"
        fi
        cp -v "${CPFILE}" "${TARGET_DIR}/${CPFILE}"
    done
    popd
}

function validate_output {
    echo "Listing output files"
    local IFS=":"
    for IMAGE in ${KERNEL_IMAGES};do
        if [ ! -f ${TARGET_DIR}/${IMAGE} ]; then
            echo "ERROR: Missing kernel output image ${IMAGE}" >&2
            exit 1
        fi
        ls -l ${TARGET_DIR}/${IMAGE}
    done
}

################################################################################
#
#  M A I N
#
################################################################################

# Phase 1: Set up execution
validate_input_params
source "${CONFIG_FILE}"
validate_cross_compiler
setup_output_dir
TARGET_DIR="$(cd "${TARGET_DIR}" && pwd)"
display_config

# Phase 2: Set up environment
download_toolchain
extract_tarball

# Phase 3: build
exec_build_kernel

# Phase 4: move to output
copy_to_output

# Phase 5: verify output
validate_output