Docker Raspberry Pi 3 kernel builder

Docker image to build a Raspberry Pi 3 kernel for the arm architecture

How to use

Building a kernel using the rpi3-kernel-builder Docker image works according to the following conventions. Configuration is done using environment variables:

• The kernel sources should be made available at /workdir
• The build will output to /workdir/build
• The output is a file called <kernelversion>.tar.gz which contains:
  • The kernel
  • The kernel modules
  • The kernel firmware
  • Overlays
  • config.txt if available in the sources
  • cmdline.txt if available in the sources
  • dt-blob.bin if dt-blob.dts is available in the sources
• To apply patches to the kernel sources make the patches available at PATCH_DIRS. This is a space separated array of paths. The patches need to have the extension .patch
• The kernel can be configured using a defconfig or using all*config. The default is to configure using bcm2709_defconfig
  • To override the default defconfig set DEFCONFIG to the defconfig's name and make sure the defconfig is made available at the correct path. For example DEFCONFIG=my_defconfig with my_defconfig being available at arch/arm/configs/my_defconfig'
  • To configure using all*config set ALLCONFIG to one of the allconfig options allyesconfig, allmodconfig, allnoconfig or randconfig. To override which config is used as the starting point set KCONFIG_ALLCONFIG to the path of the config file. For example ALLCONFIG=/workdir/configs/myminimalconfig
• The amount of jobs used by make will default to the value returned by nproc. To override this set the MAKEFLAGS environment variable. For example MAKEFLAGS=-j8.

Example usage

# Checkout kernel sources
$ git clone --single-branch --branch rpi-4.14.y --depth 1 https://www.github.com/raspberrypi/linux

# Build a kernel archive using the docker image
# using a volume mount for the linux sources to /workdir
$ cd linux
$ docker run --rm -ti -v "${PWD}":/workdir simonvanderveldt/rpi3-kernel-builder

# When the build is done the kernel archive is available in the build directory
$ ls -ahl build/
total 28M
drwxr-xr-x 2 simon simon    6 Feb  3 23:21 .
drwxr-xr-x 5 simon simon    6 Feb  3 23:08 ..
-rw-r--r-- 1 root  root  178K Feb  3 23:21 kernel-4.9.59-0.0.7-g8172bbc.sha256
-rw-r--r-- 1 root  root   11M Feb  3 23:21 kernel-4.9.59-0.0.7-g8172bbc.tar.gz

Attribution

Based on:

• https://github.com/DieterReuter/rpi64-kernel
• https://autostatic.com/2017/06/27/rpi-3-and-the-real-time-kernel/