build

#!/usr/bin/env bash
set -x -e

# Use -j<nproc> as default if MAKEFLAGS is not set
if [ -z "${MAKEFLAGS}" ]; then
  export MAKEFLAGS="-j$(nproc)"
fi

ROOT_DIR="${ROOT_DIR:-${PWD}}"
LINUX_SRC_DIR="${LINUX_SRC_DIR:-${ROOT_DIR}/linux}"
echo ${ROOT_DIR}
echo ${LINUX_SRC_DIR}

# Make sure the source directory and destination directory are cleaned up
if [ -d "${LINUX_SRC_DIR}" ]; then
    echo "Removing linux source: ${LINUX_SRC_DIR}"
    rm -rf "${LINUX_SRC_DIR}"
fi

# Checkout the linux source directory
git clone --single-branch --branch rpi-4.19.y --depth 1 https://www.github.com/raspberrypi/linux ${LINUX_SRC_DIR}
cd "${LINUX_SRC_DIR}"

# Create the temporary install directory
KDEST="${LINUX_SRC_DIR}/install"
echo "Creating install directory: ${KDEST}"
mkdir -p "${KDEST}"

# Checkout the rtl8812au driver
(
    cd drivers/net/wireless/realtek
    git clone -b v5.2.20 https://github.com/aircrack-ng/rtl8812au.git
    cd rtl8812au

    sed -i 's/CONFIG_PLATFORM_I386_PC = y/CONFIG_PLATFORM_I386_PC = n/' Makefile
    sed -i 's/CONFIG_PLATFORM_ARM_RPI = n/CONFIG_PLATFORM_ARM_RPI = y/' Makefile
    # per justins request commented out
    # sudo sed -i 's/CONFIG_USB2_EXTERNAL_POWER = n/CONFIG_USB2_EXTERNAL_POWER = y/' Makefile
    sed -i 's/export TopDIR ?= $(shell pwd)/export TopDIR2 ?= $(shell pwd)/' Makefile
    sed -i '/export TopDIR2 ?= $(shell pwd)/a export TopDIR := $(TopDIR2)/drivers/net/wireless/realtek/rtl8812au/' Makefile

    # Change the STBC value to make all antennas send with awus036ACH
    (
	cd core
	sed -i 's/u8 fixed_rate = MGN_1M, sgi = 0, bwidth = 0, ldpc = 0, stbc = 0;/u8 fixed_rate = MGN_1M, sgi = 0, bwidth = 0, ldpc = 0, stbc = 1;/' rtw_xmit.c
    )
)

# Checkout the v4l2loopback driver
(
    cd drivers/media
    git clone https://github.com/RespawnDespair/v4l2loopback.git
    # in Make file change CONFIG_PLATFORM_I386_PC = y -> n, CONFIG_PLATFORM_ARM_RPI = n -> y and TopDir
)

# Apply the patches
PATCH_DIRS="${PATCH_DIR:-${ROOT_DIR}/patches}"
patch_dir_array=( "${PATCH_DIRS}" )
for patch_dir in "${patch_dir_array[@]}"
do
  # Apply patches if `patch_dir` exists
  if [ -d "${patch_dir}" ]; then
    echo "Applying patches from ${patch_dir}"
    for patch in "${patch_dir}/"*.patch; do
      echo "Applying patch ${patch}"
      patch -p1 < "${patch}"
    done
  fi
done

build_kernel() {
    KERNEL=$1
    KCONFIG=$2

    # Condigure the kernel
    PATH=${PATH}:/opt/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin
    make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- ${KCONFIG}

    # Change some config defaults
    sed -i 's/^.*CONFIG_NET_FOU .*$/CONFIG_NET_FOU=m/' .config
    sed -i 's/^.*CONFIG_RTL8812AU .*$/CONFIG_RTL8812AU=m/' .config
    sed -i 's/^.*CONFIG_CFG80211_CERTIFICATION_ONUS.*$/CONFIG_CFG80211_CERTIFICATION_ONUS=y/' .config
    sed -i 's/^.*CONFIG_CFG80211_REQUIRE_SIGNED_REGDB.*$/#CONFIG_CFG80211_REQUIRE_SIGNED_REGDB is not set/' .config
    sed -i 's/^.*CONFIG_CFG80211_USE_KERNEL_REGDB_KEYS.*$/#CONFIG_CFG80211_USE_KERNEL_REGDB_KEYS is not set/' .config

    # Store and print kernelrease
    make kernelrelease
    KERNEL_VERSION=$(make kernelrelease | sed 's/[-+].*//g')
    echo "Building kernel ${KERNEL_VERSION} ${KERNEL} usind config ${KCONFIG}"

    # Build everything
    yes "" | make ${MAKEFLAGS} ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage modules dtbs
    yes "" | make ${MAKEFLAGS} ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bindeb-pkg
    
    # Copy the kernel and modules to the build destination
    mkdir -p "${KDEST}/boot"
    cp arch/arm/boot/zImage "${KDEST}/boot/${KERNEL}.img"
    INSTALL_MOD_PATH="${KDEST}" make modules_install

    # Install the kernel headers into the build destination
    make headers_install ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- INSTALL_HDR_PATH="${KDEST}/usr/include"

    # Copy the overlays to the build destination
    mkdir -p "${KDEST}/boot/overlays"
    cp arch/arm/boot/dts/*.dtb "${KDEST}"/boot/
    cp arch/arm/boot/dts/overlays/*.dtb* "${KDEST}"/boot/overlays/
    cp arch/arm/boot/dts/overlays/README "${KDEST}"/boot/overlays/
}


# Build the kernel for armv6 (Pi 1, Pi Zero, Pi Zero W, or Compute Module)
build_kernel "kernel" "bcmrpi_defconfig"
build_kernel "kernel7" "bcm2709_defconfig"
build_kernel "kernel7l" "bcm2711_defconfig"

# Copy the files into the kernel build destination
cd ${ROOT_DIR}/files
cp -a * ${KDEST}

# Create the final build destination directory
cd ${ROOT_DIR}
DIR_NAME=rpi_kernels_${KERNEL_VERSION}_`date +"%G-%m-%d"`
BUILD_DEST="${PWD}/${DIR_NAME}"
if [ -d "${BUILD_DEST}"]; then
    rm -rf "${BUILD_DEST}"
fi
mkdir -p "${BUILD_DEST}"

# Create a tarball of the kernel build results
cd "${KDEST}"
tar cvzf "${BUILD_DEST}/kernels.tar.gz" *

# Copy the debs into the build destination
cd "${ROOT_DIR}"
mv linux-* "${BUILD_DEST}"

echo "Files are in: ${BUILD_DEST}"

# Zip it all up
#zip -r "${DIR_NAME}.zip" "${DIR_NAME}"