Jumpnow Technologies


Building Wandboard Systems with Buildroot

27 Dec 2017

This post is about building Linux systems for i.MX6 Wandboards boards using Buildroot.

Buildroot is a popular alternative to Yocto for building custom embedded Linux systems.

With a few exceptions you can build a similar Linux system with either tool.

I am using a Buildroot clone I created in Github to track my Buildroot customizations.

The [master] branch of the repository is a mirror of the official Buildroot repository.

The default [jumpnow] branch has a few additions on top of [master] for my own customizations and is what I am using for these examples.

The defconfig is where non-default build information is stored. There is a generic wandboard_defconfig in the Buildroot repo.

You will want to create a custom defconfig for your project. The one I am using is called jumpnow_wandboard_defconfig.

To build a system, run the following (see the ccache notes below)

~$ git clone -b jumpnow https://github.com/jumpnow/buildroot
~$ cd buildroot
~/buildroot$ make jumpnow_wandboard_defconfig
~/buildroot$ make

Note: Don’t run make with a -jN argument. The main Makefile is not designed to be run as a parallel build. The sub-projects will be run in parallel automatically.

If you are missing tools on your workstation, you will get error messages telling you what you are missing. The dependencies are nothing out of the ordinary for a developer workstation and you can search the web for the particular packages you need to install for your distro.

The command

make jumpnow_wandboard_defconfig

created a .config file that completely describes to Buildroot how to generate the system.

When the build is done, insert an SD card and copy the image like this

~/buildroot$ sudo dd if=output/images/wand-sdcard.img of=/dev/sdb bs=1M

Replace /dev/sdb with the location the SD card shows up on your workstation.

Customizing the Build

The Buildroot Documentation is good and you should probably be reading that first.

One easy optimization is use ccache to reduce redundant work by the C/C++ preprocessor.

Make sure your workstation has ccache installed, then run the Buildroot configuration tool after you have your initial .config generated.

~/buildroot$ make menuconfig

Under Build options select Enable compiler cache and then save the configuration. This will update your .config.

You will need the ncurses development package for your distribution before you can run menuconfig.

After that run make as usual to build your system.

Another option I’ve been using is to save the downloaded source files to a location outside the buildroot repository.

The download location is determined by the BR2_DL_DIR variable in the config


Or it can be set as an environment variable in the shell

export BR2_DL_DIR=${HOME}/dl

This allows you to share common downloads among different builds and if you ever delete the Buildroot repository you won’t lose the downloads.

Another option is to build externally outside of the Buildroot repository.

You can specify it this way when you do the first make <some_defconfig>.

~/buildroot$ make O=/br5/wand jumpnow_wandboard_defconfig

After that, go to the directory you chose to run the Buildroot make commands

~/buildroot$ cd /br5/wand
/br5/wand$ make menuconfig (optional)
/br5/wand$ make

In this particular case I have /br5/wand on a drive partition separate from my workstation rootfs and my home directory.

System Overview

I am using wandboard quads for some network services on my LAN. They run headless so I have all display modules stripped from my kernels.

Attach a serial console and you will see this on boot

Welcome to Buildroot
wandboard login:

The only user is root with password jumpnowtek. This is set in the defconfig.

# uname -a
Linux wandboard 4.14.6-jumpnow #1 SMP Sun Dec 17 05:03:55 EST 2017 armv7l GNU/Linux

# free
              total        used        free      shared  buff/cache   available
Mem:        2063808       16308     2028664          72       18836     1988884
Swap:             0           0           0

The images are only 2GB in size, again specified in the defconfig, but the system uses less then 100M.

# df -h
Filesystem                Size      Used Available Use% Mounted on
/dev/root                 1.8G     88.8M      1.6G   5% /
devtmpfs                999.2M         0    999.2M   0% /dev
tmpfs                  1007.7M         0   1007.7M   0% /dev/shm
tmpfs                  1007.7M     28.0K   1007.7M   0% /tmp
tmpfs                  1007.7M     44.0K   1007.7M   0% /run

Both ethernet and wifi work.

# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:1F:7B:B4:03:79
          inet addr:  Bcast:  Mask:
          inet6 addr: fe80::21f:7bff:feb4:379/64 Scope:Link
          RX packets:95 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:6846 (6.6 KiB)  TX bytes:1550 (1.5 KiB)

lo        Link encap:Local Loopback
          inet addr:  Mask:
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

wlan0     Link encap:Ethernet  HWaddr 40:2C:F4:AE:14:B0
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

An ssh server is running, but not much else

# netstat -an
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0    *               LISTEN
tcp        0      0 :::22                   :::*                    LISTEN
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags       Type       State         I-Node Path
unix  3      [ ]         DGRAM                     10507 /dev/log
unix  2      [ ACC ]     SEQPACKET  LISTENING       1148 /run/udev/control
unix  2      [ ]         DGRAM                     11948
unix  3      [ ]         DGRAM                     11953
unix  3      [ ]         DGRAM                     11952

And I have Python3 installed

# python3
Python 3.6.3 (default, Dec 17 2017, 04:56:51)
[GCC 6.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> quit()

for some things I am working on.

Using the Buildroot cross-toolchain

Some quick notes on using the cross-toolchain.

The toolchain gets installed under the build output/host directory.

In my example where I used an external build directory of /br5/wand

~/buildroot$ make O=/br5/wand jumpnow_wandboard_defconfig

my build output ended up here


The cross-compiler and associated tools can be found under


The toolchain is not relocatable. You must use it in place.

To use add the path /br5/wand/host/usr/bin to your PATH environment variable and invoke the compiler by name, in this case arm-linux-gcc, arm-linux-g++, etc…

Some quick examples, first add the PATH to the cross-compiler

$ export PATH=/br5/wand/host/usr/bin:${PATH}
$ echo $PATH

A simple C, Makefile example

~/projects$ git clone https://github.com/scottellis/serialecho
Cloning into 'serialecho'...

~/projects$ cd serialecho/

~/projects/serialecho$ cat Makefile
TARGET = serialecho

$(TARGET) : serialecho.c
        $(CC) serialecho.c -o $(TARGET)

        rm -f $(TARGET)

~/projects/serialecho$ export CC=arm-linux-gcc

~/projects/serialecho$ make
arm-linux-gcc serialecho.c -o serialecho

~/projects/serialecho$ file serialecho
serialecho: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, for GNU/Linux 4.14.0, not stripped