Raspberry Pi 2 - Kernel 4.4 and NFTables

Install Dependencies

apt-get -y install git-core bc build-essential 

Download the Kernel

cd ~
git clone --depth=1 -b rpi-4.4.y https://github.com/raspberrypi/linux rpi-kernel
cd rpi-kernel

Notice the branch flag (-b rpi-4.4.y)

Build the Kernel

Choose one way to build: (I really advice to cross-compile, ie: from a Debian 8 amd64 virtual machine)

From the Raspberry (1h30 on a Raspberry Pi 2)

• For Raspberry Pi 1: (or compute module)

KERNEL=kernel
make bcmrpi_defconfig

! At this precise step, please refer to 'Configure the Kernel' section !

make zImage modules dtbs

• For Raspberry Pi 2:

KERNEL=kernel7
make bcm2709_defconfig

! At this precise step, please refer to 'Configure the Kernel' section !

make -j4 zImage modules dtbs

• Common for both:

make modules_install
cp arch/arm/boot/dts/*.dtb /boot/
cp arch/arm/boot/dts/overlays/*.dtb* /boot/overlays/
cp arch/arm/boot/dts/overlays/README /boot/overlays/
scripts/mkknlimg arch/arm/boot/zImage /boot/$KERNEL.img

Cross-Compiling (10min on a common Intel i5)

Install Toolchain

cd ~
git clone https://github.com/raspberrypi/tools
cd rpi-kernel

Build

Note for 32bits build environment: remove the -x64 from CROSS_COMPILE path

• For Raspberry Pi 1: (or compute module)

KERNEL=kernel
make ARCH=arm CROSS_COMPILE=~/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- bcmrpi_defconfig

• For Raspberry Pi 2:

KERNEL=kernel7
make ARCH=arm CROSS_COMPILE=~/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- bcm2709_defconfig

• For both:

! At this precise step, please refer to 'Configure the Kernel' section !

make -j4 ARCH=arm CROSS_COMPILE=~/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- zImage modules dtbs

Change the -j4 accordingly (number of threads, typically the number of CPU you want to use to build)

Deploy

Connect the sdcard to the machine you're building with, and find the two partitions with the command lsblk

Typically sdb1 which is the /boot partition (fat32) and sdb2 which is the root / (ext4)

Then:

mkdir /mnt/fat32
mkdir /mnt/ext4
mount /dev/sdb1 /mnt/fat32
mount /dev/sdb2 /mnt/ext4

cd ~/rpi-kernel
make ARCH=arm CROSS_COMPILE=~/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- INSTALL_MOD_PATH=/mnt/ext4 modules_install

cp /mnt/fat32/$KERNEL.img /mnt/fat32/$KERNEL-backup.img
scripts/mkknlimg arch/arm/boot/zImage /mnt/fat32/$KERNEL.img
cp arch/arm/boot/dts/*.dtb /mnt/fat32/
cp arch/arm/boot/dts/overlays/*.dtb* /mnt/fat32/overlays/
cp arch/arm/boot/dts/overlays/README /mnt/fat32/overlays/
umount /mnt/fat32
umount /mnt/ext4

Configure the Kernel

Simply replace the .config with the one I'm providing here, and you're done.

! Caution: You have to execute this step right before the make [...] zImage modules dtbs command !