#
# Build and Setup RPi2 Kernel
#

# Load utility functions
. ./functions.sh

# Fetch and build latest raspberry kernel
if [ "$BUILD_KERNEL" = true ] ; then
  # Setup source directory
  mkdir -p $R/usr/src

  # Copy existing kernel sources into chroot directory
  if [ -n "$KERNEL_SRCDIR" ] && [ -d "$KERNEL_SRCDIR" ] ; then
    # Copy kernel sources
    cp -r "${KERNEL_SRCDIR}" "${R}/usr/src"

    # Clean the kernel sources
    if [ "$KERNEL_CLEANSRC" = true ] ; then
      make -C $R/usr/src/linux ARCH=${KERNEL_ARCH} CROSS_COMPILE=${CROSS_COMPILE} mrproper
    fi
  else # KERNEL_SRCDIR=""
    # Fetch current raspberrypi kernel sources
    git -C $R/usr/src clone --depth=1 https://github.com/raspberrypi/linux
  fi

  # Calculate optimal number of kernel building threads
  if [ "$KERNEL_THREADS" = "1" ] ; then
    if [ -r /proc/cpuinfo ] ; then
      KERNEL_THREADS=$(grep -c processor /proc/cpuinfo)
    fi
  fi

  if [ "$KERNEL_CONFIGSRC" = true ] ; then
    # Load default raspberry kernel configuration
    make -C $R/usr/src/linux ARCH=${KERNEL_ARCH} CROSS_COMPILE=${CROSS_COMPILE} ${KERNEL_DEFCONFIG}

    # Start menu-driven kernel configuration (interactive)
    if [ "$KERNEL_MENUCONFIG" = true ] ; then
      make -C $R/usr/src/linux ARCH=${KERNEL_ARCH} CROSS_COMPILE=${CROSS_COMPILE} menuconfig
    fi
  fi

  # Cross compile kernel and modules
  make -C $R/usr/src/linux -j${KERNEL_THREADS} ARCH=${KERNEL_ARCH} CROSS_COMPILE=${CROSS_COMPILE} zImage modules dtbs

  # Check if kernel compilation was successful
  if [ ! -r $R/usr/src/linux/arch/${KERNEL_ARCH}/boot/zImage ] ; then
    echo "error: kernel compilation failed!"
    cleanup
    exit 1
  fi

  # Install kernel modules
  if [ "$ENABLE_REDUCE" = true ] ; then
    make -C $R/usr/src/linux ARCH=${KERNEL_ARCH} CROSS_COMPILE=${CROSS_COMPILE} INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=../../.. modules_install
  else
    make -C $R/usr/src/linux ARCH=${KERNEL_ARCH} CROSS_COMPILE=${CROSS_COMPILE} INSTALL_MOD_PATH=../../.. modules_install
  fi

  # Install kernel headers
  if [ "$KERNEL_HEADERS" = true ] ; then
    make -C $R/usr/src/linux ARCH=${KERNEL_ARCH} CROSS_COMPILE=${CROSS_COMPILE} INSTALL_HDR_PATH=../.. headers_install
  fi

  # Copy and rename compiled kernel to boot directory
  mkdir $R/boot/firmware/
  $R/usr/src/linux/scripts/mkknlimg $R/usr/src/linux/arch/${KERNEL_ARCH}/boot/zImage $R/boot/firmware/kernel7.img

  # Copy dts and dtb device definitions
  mkdir $R/boot/firmware/overlays/
  cp $R/usr/src/linux/arch/${KERNEL_ARCH}/boot/dts/*.dtb $R/boot/firmware/
  cp $R/usr/src/linux/arch/${KERNEL_ARCH}/boot/dts/overlays/*.dtb* $R/boot/firmware/overlays/
  cp $R/usr/src/linux/arch/${KERNEL_ARCH}/boot/dts/overlays/README $R/boot/firmware/overlays/

  # Remove kernel sources
  if [ "$KERNEL_RMSRC" = true ] ; then
    rm -fr $R/usr/src/linux
  fi

  # Install raspberry bootloader and flash-kernel packages
  chroot_exec apt-get -qq -y --no-install-recommends install raspberrypi-bootloader-nokernel
else # BUILD_KERNEL=false
  # Kernel installation
  chroot_exec apt-get -qq -y --no-install-recommends install linux-image-${COLLABORA_KERNEL} raspberrypi-bootloader-nokernel

  # Install flash-kernel last so it doesn't try (and fail) to detect the platform in the chroot
  chroot_exec apt-get -qq -y install flash-kernel

  VMLINUZ="$(ls -1 $R/boot/vmlinuz-* | sort | tail -n 1)"
  [ -z "$VMLINUZ" ] && exit 1
  cp $VMLINUZ $R/boot/firmware/kernel7.img
fi

# Setup firmware boot cmdline
if [ "$ENABLE_SPLITFS" = true ] ; then
  CMDLINE="dwc_otg.lpm_enable=0 root=/dev/sda1 rootfstype=ext4 rootflags=commit=100,data=writeback elevator=deadline rootwait net.ifnames=1 console=tty1 ${CMDLINE}"
else
  CMDLINE="dwc_otg.lpm_enable=0 root=/dev/mmcblk0p2 rootfstype=ext4 rootflags=commit=100,data=writeback elevator=deadline rootwait net.ifnames=1 console=tty1 ${CMDLINE}"
fi

# Add serial console support
if [ "$ENABLE_CONSOLE" = true ] ; then
  CMDLINE="${CMDLINE} console=ttyAMA0,115200 kgdboc=ttyAMA0,115200"
fi

# Remove IPv6 networking support
if [ "$ENABLE_IPV6" = false ] ; then
  CMDLINE="${CMDLINE} ipv6.disable=1"
fi

# Install firmware boot cmdline
echo "${CMDLINE}" >$R/boot/firmware/cmdline.txt

# Install firmware config
install_readonly files/boot/config.txt $R/boot/firmware/config.txt

# Setup minimal GPU memory allocation size: 16MB (no X)
if [ "$ENABLE_MINGPU" = true ] ; then
  echo "gpu_mem=16" >>$R/boot/firmware/config.txt
fi

# Create firmware configuration and cmdline symlinks
ln -sf firmware/config.txt $R/boot/config.txt
ln -sf firmware/cmdline.txt $R/boot/cmdline.txt

# Install and setup kernel modules to load at boot
mkdir -p $R/lib/modules-load.d/
install_readonly files/modules/rpi2.conf $R/lib/modules-load.d/rpi2.conf

# Load hardware random module at boot
if [ "$ENABLE_HWRANDOM" = true ] ; then
  sed -i "s/^# bcm2708_rng/bcm2708_rng/" $R/lib/modules-load.d/rpi2.conf
fi

# Load sound module at boot
if [ "$ENABLE_SOUND" = true ] ; then
  sed -i "s/^# snd_bcm2835/snd_bcm2835/" $R/lib/modules-load.d/rpi2.conf
fi

# Install kernel modules blacklist
mkdir -p $R/etc/modprobe.d/
install_readonly files/modules/raspi-blacklist.conf $R/etc/modprobe.d/raspi-blacklist.conf

# Install and setup fstab
install_readonly files/mount/fstab $R/etc/fstab
if [ "$ENABLE_SPLITFS" = true ] ; then
  sed -i 's/mmcblk0p2/sda1/' $R/etc/fstab
fi

# Install sysctl.d configuration files
install_readonly files/sysctl.d/81-rpi-vm.conf $R/etc/sysctl.d/81-rpi-vm.conf