Building a custom toolchain for the BeagleBone

This post is about creating a custom (linaro) toolchain using using cross-ng. The motivation for this came about when I found I was unable to build the ffmpeg library directly on a beaglebone (specifically, the older beaglebone white model) because of insufficient memory during the build process 1.

First, we need to download cross-ng with linaro support. I used the source at https://github.com/Christopher83/linaro_crosstool-ng. To install crosstool-ng:

git clone https://github.com/Christopher83/linaro_crosstool-ng
cd linaro_crosstool-ng
./bootstrap
./configure --prefix=/install/path (e.g. /opt/cross)
make
sudo make install

Then, make a directory to build your tool chain

mkdir /home/<user>/ctng
cd /home/<user>/ctng

Now, we configure the toolchain using the crosstool-ng interface

/opt/cross/bin/ct-ng menuconfig

• Under Path and misc options
  • Select Try features marked as EXPERIMENTAL
  • Set Prefix directory to `${HOME}/x-tools/${CT_TARGET}’ or whatever you choose 2
  • Set Number of parallel jobs to 2 times the number of CPU cores on the host
• Under Operating Sytems change Target OS to linux
• Under Target options
  • Set Target Architecture to arm
  • Select Use the MMU
  • Set Endianness to Little endian
  • Set Default instruction set mode to thumb
  • Select Use EABI
  • Set Tune for CPU to cortex-a8
  • Set Floating point to hardware (FPU)
  • Set Use specific FPU to neon
  • Set Architecture level to armv7-a
• Under Toolchain Options set Tuple's Vendor String to linaro
• Under C Library
  • Set C Library to eglibc
  • (Important) Set eglibc version to Linaro 2.19-2014.08 (should be same as version of glibc on target)
• Under C Compiler
  • Select Show Linaro versions
  • Set gcc version to latest linaro-gcc
  • Optionally, select additional supported languages (e.g. C++)

Exit and save settings. Then, to build the toolchain, type

/opt/cross/bin/ct-ng build

This will take a while (20 min on my quad core i7). When it’s done create a file containing the following lines:

export PATH=$PATH:$HOME/x-tools/arm-linaro-linux-gnueabihf/bin
export CCPREFIX="$HOME/x-tools/arm-linaro-linux-gnueabihf/bin/arm-linaro-linux-gnueabihf-"

You can now source this file anytime to set up the environment variables necessary to compile with your toolchain. Let’s sanity check the compiler:

$ arm-linaro-linux-gnueabihf-gcc --version
arm-linaro-linux-gnueabihf-gcc (crosstool-NG 1.20.0) 4.9.3 20150209 (prerelease)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ cat > test.c
#include <stdio.h>
int main() { printf("Hello, world!\n"); return 0; }
^D

$ arm-linaro-linux-gnueabi-gcc -o test test.c

Copy the test executable from this last step to your beaglebone and execute it there. You should see the Hello World output. Success!

adding swap space.

cannot be run as root but writing to /opt/cross requires root.