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rpi-kernel

Build a Raspberry Pi 0/1 and 2/3/3+ kernel with all kernel modules running Docker.

Build inputs

Kernel git commit

In the build script scripts/compile_kernel.sh there is a git commit hash to pin the build to this exact commit to make it reproducible.

If you want to build another kernel version, have a look at the upstream repo https://github.com/raspberrypi/linux and check for a good git commit hash and change the line

LINUX_KERNEL_COMMIT="c8baa9702cc99de9614367d0b96de560944e7ccd"

Kernel configs

In the local directory kernel_configs/ are two configuration files for Pi 0/1 and Pi 2/3/3+.

• rpi1_docker_defconfig
• rpi2_3_docker_defconfig

These configuration files are created from an initial make menuconfig and activating all kernel modules we need to run docker on the Raspberry Pi.

The differences to the upstream Raspberry Pi kernel is

$ diff kernel_configs/rpi1_docker_defconfig /var/kernel_build/cache/linux-kernel/arch/arm/configs/bcmrpi_defconfig
16d15
< CONFIG_MEMCG_SWAP=y
18,20d16
< CONFIG_CFS_BANDWIDTH=y
< CONFIG_RT_GROUP_SCHED=y
< CONFIG_CGROUP_PIDS=y
25d20
< CONFIG_CGROUP_PERF=y
354,355d348
< CONFIG_NET_L3_MASTER_DEV=y
< CONFIG_CGROUP_NET_PRIO=y
461d453
< CONFIG_IPVLAN=m

Build outputs

Kernel deb packages

The two relevant kernel deb packages are copied to build_results/kernel/${KERNEL_DATETIME}/.

• kernel-commit.txt
• raspberrypi-kernel_${KERNEL_VERSION}_armhf.deb
• raspberrypi-kernel-headers_${KERNEL_VERSION}_armhf.deb

Build with Vagrant

To build the SD card image locally with Vagrant and VirtualBox, enter

vagrant up

Recompile kernel

Only on first boot the kernel will be compiled automatically. If you want to compile again, use these steps:

vagrant up
vagrant ssh
sudo su
/vagrant/scripts/compile_kernel.sh

Update kernel configs

To update the two kernel config files you can use this steps.

vagrant up
vagrant ssh
sudo su
MENUCONFIG=1 /vagrant/scripts/compile_kernel.sh

This will only call the make menuconfig inside the toolchain and copies the updated kernel configs back to kernel_configs/ folder to be committed to the GitHub repo.

Test kernel

To test the new kernel, copy all DEB packages to your Pi and login as root. Then install the following packages:

dpkg -i raspberrypi-kernel_${KERNEL_DATETIME}_armhf.deb

dpkg -i raspberrypi-kernel-headers_${KERNEL_DATETIME}_armhf.deb

Reboot your Pi.