====== rootfs with Buildroot ======

To create your own rootfs with Buildroot, clone the Buildroot Repository from [[https://github.com/buildroot/buildroot|Github]]. Make sure to checkout a release version of buildroot and not the master branch!

Then configure buildroot according to your needs. Configuration can be done typing the following command in the root folder of buildroot:
<code>
$ make menuconfig
</code>

For the Colibri iMX6 you can find a buildroot defconfig in our NTB Buildroot-Fork: https://github.com/ntb-ch/buildroot/tree/cb20

Bildroot will build a rootfs image from your config and if you want to add some specific files and users this can be done with a rootfs overlay and a user file.
The current rootfsOverlay for the iMX6 running a 3.14 Preempt RT Kernel can be found on [[https://github.com/ntb-ch/cb20/tree/master/Software/rootfs|Github]]. In our image these files are:
  * Kernel modules for [[http://flink-project.ch|flink]] and [[https://github.com/ntb-ch/fpga_loader|FPGA Loader]] (/lib/modules/3.14xxx/kernel)
  * Startup Script to load the FPGA at boot-time and load the needed kernel modules for flink (/etc/init.d/S60flink)
  * FPGA config file (/lib/firmware/cb20.rbf)
  * firmware for a Edimax Wifi Stick (EW-7811) (/lib/firmware/rtlwifi)
  * flink Userspace Library (/opt/cb20/lib/libflink.so) and flink tools (lsflink in /opt/cb20/bin/)
  * symlinks for all libraries from /usr/lib to /opt/cb20/lib
  * initial-setup script: Since our rootfs is mounted read-only it will mount the filesystem read-write so that the SSH-Keys can be generated. Also the read-write mounted data partition is formatted initially (/opt/cb20/bin/initial-setup-sh)

The path to the rootfs overlay has to be entered in your Buildroot config at ''System configuration -> Root filesystem'' overlay. 

If you want to add additional users (except root), you can add a user table file to Buildroot. The path to this file needs to be entered in your Buildroot config at ''System configuration -> Path to the users tables''. An example for this file can be found also in the CB20 repository mentioned earlier.