I cross-compiled ROS for aarch64 to use it on a Jetson nano/tx2

Overview

I started with this old repository which was for ROS indigo for armhf. Many cross compilation scripts were readily adaptable for melodic. However some needed a bit of tweaking.

My cross compilation scripts are available in this repo which is a fork of the previously mentioned repo. Following ROS components can be cross compiled with it.

  • ros_comm
  • common_msgs
  • sensor_msgs
  • image_transport
  • vision_opencv
  • tf
IMPORTANT:

If you want to cross compile, follow the instructions on the README file in the repository. This is not a “how to” guide. This just explains some stuff I have done there.

Important changes for aarch64

  armhf aarch64
toolset gcc-arm gcc-aarch64
c cross compiler arm-linux-gnueabihf-gcc aarch64-linux-gnu-gcc
c++ cross compiler arm-linux-gnueabihf-g++ aarch64-linux-gnu-g++

Changes from indigo to melodic

Indigo needed tinyxml but melodic (Ubuntu18) needs tinyxml2

Below new packages were added for melodic

Compilation

The toolchains should be installed first alongside with other needed dependencies.

sudo apt install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu

Then all the build scripts must be run (in the correct order – boost needs python and so on). Use the scripts/build_dependencies.sh.

Use scripts/xcompile.sh to start the compilation. It does the following

  1. catkin init and config the build workspace
  2. Use rosinstall to create a .rosinstall file containing all the packages needed for the build
  3. Populate workspace with needed packages using the .rosinstall file
  4. Build with catkin build
  5. Do some post-processing stuff (explained in the ‘Post processing’ section)

Post processing

Some post processing had to be done in the xcompile.sh script since there was some problems running the cross-compiled ROS as it was.

The path <install path>/lib contains the cross-compiled packages’ shared libraries. But ROS commands could not find them. Therefore LD_LIBRARY_PATH had to be modified.

LD_LIBRARY_PATH='"${INSTALL_PREFIX}"'/lib:$LD_LIBRARY_PATH

$INSTALL_PREFIX is the install path provided at the compilation.

In the build machine, aarch64 libraries were installed into the path /usr/aarch64-linux-gnu/lib/. But in the host (a Jetson nano) they were in /usr/lib/aarch64-linux-gnu/ (had a problem with ROS not being able to find libpthread.so). Had to modify the said path for everything to work

find $INSTALL_PREFIX -type f -exec sed -i 's|/usr/aarch64-linux-gnu/lib/|/usr/lib/aarch64-linux-gnu/|g' {} \;

These are done at the end of xcompile.sh

Problems

gpgme, gpgrt and log4cxx cross compilations were unsuccessful. Since the time for this was limited, relevant library files are copied from the target machine to the install directory. The files are available in the misc/ directory.

Cross compiling packages

I was first searching for cross compiling my own set of packages. Asking about this on the Jetson dev forum lead to an interesting discussion: link.

Later I found out that there already is a package for that provided in rostooling: link.