There are numerous prebuilt kernel images available on the NTB ftp server:

• 3.14
• 3.14 RT
• 4.9
• 4.9 RT

Also there are 2 different rootfs images available:

• minimal rootfs
• pathos rootfs

The minimal rootfs is the result of a build without any rootfs customisation. It is well suited for testing a new kernel build without any of the pathos modifications. Pathos rootfs contains the custom overlay for pathos and includes the pathos customisations. It is the result of following this entire build process.

For information on loading a kernel please refer to Loading Image to a Board

Buildroot is the recommended way for building new kernel and rootfs images. Note that while both are automatically built they can be updated seperately (use with caution). While the device tree is also compiled during each build it is not necessary to reupload it to the board if the device tree (.dts) was not changed.

Download the latest stable version of buildroot: replace a.b.x with the latest tagged release of buildroot (the prebuilt images were built using 2018.08.x)

  git clone -b a.b.x https://github.com/buildroot/buildroot/

change into buildroot directory

  cd buildroot

Download our default buildroot config for the cb20 board (colibri i.MX6 SoC)

  git clone / wget <link-to-config>

expand

To build images simply run:

  make

Note that at the time of writing buildroot only supports single threaded top level execution, so do not invoke make with the -j flag. However buildroot will automatically use the optimal number of parallel jobs (threads) internally.

For information on flashing the kernel image and rootfs please refer to Loading Image to a Board

configure buildroot

  make menuconfig

configure the kernel

  make linux-menuconfig

configure busybox

  make busybox-menuconfig

These are configured if you use the premade overlay. rephrase

overlay: rootfs overlay for additional files to be loaded into the rootfs image

useresColibri: user table for users in addition to root

Updating the kernel should be as simple as updating the branch and defconfig in the buildroot config. Also make sure to either update the real time patches or disable them (disabling the real time patches will result in a non-RT kernel). See RT kernel patches)