Roadrunner technical documentation

BuildRoot-at91 2020.04

BuildRoot is a set of makefiles and patches that makes it easy to generate a low footprint Embedded Linux System.

This article il just the Acme Systems version of the original article published by Microchip on tested on a RoadRunner SOM and a Berta D2 dev board


We illustrates here just how to generate the just rootfs contents. For the bootloader and Kernel image please read these articles:

The article contents has been tested using a Linux PC with Ubuntu 18.04.4 64bit

It is advisable to have a Debug Port Interface or another serial adapter

Building procedure

Install on your Linux PC the requested packages listed here:

Download BuildRoot from the Microchip repository on GitHub:

git clone

Select the right branch:

cd buildroot-at91
git checkout linux4sam-2020.04 -b buildroot-at91-linux4sam-2020.04

Insert the Acme Systems setup files applying this patch:


and apply it by typing:

patch -p1 < buildroot-at91-2020.04.patch
make acme-bertad2_defconfig

Launch the rootfs contents compilation:


This operation will take about 1 hour to download and compile any source of any part of your Linux distribution.

If everything goes well you will obtain these compressed files in output/images directory:


Create two partitions on microSD using gparted:

| Type  | Label  | Size  |
| fat32 | boot   | >8MB  |   
| ext4  | rootfs | >70MB |

Copy the bootloader, the linux kernel and the device tree blob generated before on the first microSD FAT partition:

cp boot.bin /media/$USER/boot
cp at91-sama5d2_roadrunner.dtb /media/$USER/boot/acme-roadrunner.dtb
cp zImage /media/$USER/boot

Untar the rootfs contents in the second microSD partition:

sudo tar xvf output/images/rootfs.tar -C /media/$USER/rootfs

Unmount the microSD and boot it on your RoadRonner board.

At login and password prompt type:

  • login: root
  • password: acmesystems

How to install new package on rootfs

To install new packages from the menuconfig menu type:

make menuconfig

Then exit and save the new configuration by typing:

make savedefconfig

Related links

Roadrunner technical documentation