Added: BUILD_KERNEL - build latest rpi2 kernel

2 files changed, 48 insertions, 7 deletions

diff --git a/README.md b/README.md
index 6378db3..6c2627e 100644
--- a/README.md
+++ b/README.md
@@ -152,6 +152,10 @@ Enable IPv4/IPv6 network stack hardening settings.
 ##### `CHROOT_SCRIPTS`=""
 Path to a directory with scripts that should be run in the chroot before the image is finally built. Every executable file in this direcory is run in lexicographical order.
 
+#### Kernel compilation:
+##### `BUILD_KERNEL`=false
+Build and install the latest RPi2 linux kernel. Currently only the default RPi2 kernel configuration is used. Detailed configuration parameters for customizing the kernel and minor bug fixes still need to get implemented. feel free to help.
+
 ## Logging of the bootstrapping process
 All information related to the bootstrapping process and the commands executed by the `rpi2-gen-image.sh` script can easily be saved into a logfile. The common shell command `script` can be used for this purpose:
 
diff --git a/rpi2-gen-image.sh b/rpi2-gen-image.sh
index 5b61ae2..a1d6333 100755
--- a/rpi2-gen-image.sh
+++ b/rpi2-gen-image.sh
@@ -95,6 +95,9 @@ ENABLE_FBTURBO=${ENABLE_FBTURBO:=false}
 ENABLE_HARDNET=${ENABLE_HARDNET:=false}
 ENABLE_IPTABLES=${ENABLE_IPTABLES:=false}
 
+# Kernel compilation settings
+BUILD_KERNEL=${BUILD_KERNEL:=false}
+
 # Image chroot path
 R=${BUILDDIR}/chroot
 CHROOT_SCRIPTS=${CHROOT_SCRIPTS:=""}
@@ -117,6 +120,11 @@ if [ "$(id -u)" -ne "0" ] ; then
   exit 1
 fi
 
+# Add packages required for kernel cross compilation
+if [ "$BUILD_KERNEL" = true ] ; then
+  REQUIRED_PACKAGES="${REQUIRED_PACKAGES} crossbuild-essential-armhf"
+fi
+
 # Check if all required packages are installed
 for package in $REQUIRED_PACKAGES ; do
   if [ "`dpkg-query -W -f='${Status}' $package`" != "install ok installed" ] ; then
@@ -317,14 +325,43 @@ if [ "$ENABLE_MINBASE" = false ] ; then
   chroot_exec dpkg-reconfigure -f noninteractive console-setup
 fi
 
-# Kernel installation
-# Install flash-kernel last so it doesn't try (and fail) to detect the platform in the chroot
-chroot_exec apt-get -qq -y --no-install-recommends install linux-image-${KERNEL} raspberrypi-bootloader-nokernel
-chroot_exec apt-get -qq -y install flash-kernel
+# Fetch and build latest raspberry kernel
+if [ "$BUILD_KERNEL" = true ] ; then
+  # Fetch current raspberrypi kernel sources
+  git -C $R/tmp clone --depth=1 https://github.com/raspberrypi/linux
+
+  # Load default raspberry kernel configuration
+  make -C $R/tmp/linux ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcm2709_defconfig
+
+  # Cross compile kernel and modules
+  make -C $R/tmp/linux -j 8 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage modules dtbs
+
+  # Install kernel modules
+  make -C $R/tmp/linux ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- INSTALL_MOD_PATH=../.. modules_install
 
-VMLINUZ="$(ls -1 $R/boot/vmlinuz-* | sort | tail -n 1)"
-[ -z "$VMLINUZ" ] && exit 1
-cp $VMLINUZ $R/boot/firmware/kernel7.img
+  # Copy and rename compiled kernel to boot directory
+  mkdir $R/boot/firmware/
+  $R/tmp/linux/scripts/mkknlimg $R/tmp/linux/arch/arm/boot/zImage $R/boot/firmware/kernel7.img
+
+  # Copy dts and dtb device definitions
+  mkdir $R/boot/firmware/overlays/
+  cp $R/tmp/linux/arch/arm/boot/dts/*.dtb $R/boot/firmware/
+  cp $R/tmp/linux/arch/arm/boot/dts/overlays/*.dtb* $R/boot/firmware/overlays/
+  cp $R/tmp/linux/arch/arm/boot/dts/overlays/README $R/boot/firmware/overlays/
+
+  # Install raspberry bootloader and flash-kernel
+  chroot_exec apt-get -qq -y --no-install-recommends install raspberrypi-bootloader-nokernel
+else
+  # Kernel installation
+  chroot_exec apt-get -qq -y --no-install-recommends install linux-image-${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
 
 # Set up IPv4 hosts
 echo ${HOSTNAME} >$R/etc/hostname