skylerpan / cross_compile

A tool to build ROS and ROS2 workspaces for various targets

ROS / ROS 2 Cross Compile Tool

A tool to automate compiling ROS and ROS 2 workspaces to non-native architectures.

🚧 ros_cross_compile relies on running emulated builds using QEmu, #69 tracks progress toward enabling cross-compilation.

Supported targets

This tool supports compiling a workspace for all combinations of the following:

• Architecture: armhf, aarch64, x86_64
• ROS Distro
  • ROS: kinetic, melodic
  • ROS 2: dashing, eloquent, foxy
• OS: Ubuntu, Debian

NOTE: ROS 2 supports Debian only as a Tier 3 platform. This means that there are not apt repositories available for the ROS 2 Core on this platform. Because of that, when targeting Debian for a ROS 2 workspace, you must also include the source for the core as well. It is recommended to use a release branch of ros2.repos from https://github.com/ros2/ros2 to do so, rather than master, so that you are not affected by development branch bugs and API changes.

Supported hosts

This tool officially supports running on the following host systems. Note that many others likely work, but these are being thoroughly tested.

• Ubuntu 18.04 Bionic Beaver
• OSX Mojave

Installation

Prerequisites

This tool requires that you have already installed

• Docker
  • Follow the instructions to add yourself to the docker group as well, so you can run containers as a non-root user
• Python 3.5 or higher

If you are using a Linux host, you must also install QEmu (Docker for OSX performs emulation automatically):

sudo apt-get install qemu-user-static

Installing ros_cross_compile

To install the stable release,

pip3 install ros_cross_compile

If you would like the latest nightly build, you can get it from Test PyPI

pip3 install --index-url https://test.pypi.org/simple/ ros_cross_compile

How it works, high level

1. Collect dependencies
   1. Create a Docker image that has rosdep
   2. Run the rosdep image against your target workspace to output a script that describes how to install its dependencies
2. Create "sysroot image" that has everything needed for building target workspace
   1. Use a base image for the target architecture (aarch64, armhf, ...)
   2. Install build tools (compilers, cmake, colcon, etc)
   3. Run the dependency installer script collected in Step 1 (if dependency list hasn't changed since last run, this uses the Docker cache)
3. Build
   1. Runs the "sysroot image" using QEmu emulation
   2. colcon build

Usage

This package installs the ros_cross_compile command. The command's first argument is the path to your ROS workspace.

Here is a simple invocation for a standard workflow.

ros_cross_compile /path/to/my/workspace --arch aarch64 --os ubuntu --rosdistro dashing

For information on all available options, run ros_cross_compile -h. See the following sections for information on the more complex options.

Package Selection and Build Customization

To choose which packages to install dependencies for, this tool runs colcon list on your workspace. To build, it runs colcon build.

You can provide arbitrary arguments to these commands via the colcon defaults.yaml.

You can either specify the name of this file via ros_cross_compile --colcon-defaults relative/path/to/defaults.yaml, or if not specified, a file called defaults.yaml will be used if present.

For example, there are repositories checked out in your workspace that contain packages that are not needed for your application - some repos provide many packages and you may only want one! In this scenario there is a "bringup" package that acts as the entry point to your application:

# my_workspace/defaults.yaml
list:
  # only install dependencies for source packages that my package depends on
  packages-up-to: [my_application_bringup]
build:
  # only build up to my package
  packages-up-to: [my_application_bringup]
  # example of a boolean commandline argument
  merge-install: true

Custom rosdep script

Your ROS application may need nonstandard rosdep rules. If so, you have the option to provide a script to be run before the rosdep install command collects keys.

This script has access to the "Custom data directory" same as the "Custom setup script", see the following sections. If you need any extra files for setting up rosdep, they can be accessed via this custom data directory.

Note that:

1. Rosdeps are always collected in an Ubuntu Bionic container, so scripts must be compatible with that

Here is an example script for an application that adds extra rosdep source lists

cp ./custom-data/rosdep-rules/raspicam-node.yaml /etc/ros/rosdep/custom-rules/raspicam-node.yaml
echo "yaml file:/etc/ros/rosdep/custom-rules/raspicam-node.yaml" > /etc/ros/rosdep/sources.list.d/22-raspicam-node.list
echo "yaml https://s3-us-west-2.amazonaws.com/rosdep/python.yaml" > /etc/ros/rosdep/sources.list.d/18-aws-python.list

Tool invocation for this example:

ros_cross_compile /path/to/my/workspace --arch aarch64 --os ubuntu \
  --custom-rosdep-script /path/to/rosdep-script.sh \
  --custom-data-dir /arbitrary/local/directory

Custom setup script

Your ROS application may have build needs that aren't covered by rosdep install. If this is the case (for example you need to add extra apt repos), use the option --custom-setup-script to execute arbitrary code in the sysroot container.

The path provided may be absolute, or relative to the current directory.

Keep in mind

• It's up to the user to determine whether the script is compatible with chosen base platform
• Make sure to specify non-interactive versions of commands, for example apt-get install -y, or the script may hang waiting for input
• You cannot make any assumptions about the state of the apt cache, so run apt-get update before installing packages
• The script runs as root user in the container, so you don't need sudo

Below is an example script for an application that installs some custom Raspberry Pi libraries.

apt-get update
apt-get install -y software-properties-common

# Install Raspberry Pi library that we have not provided a rosdep rule for
add-apt-repository ppa:rpi-distro/ppa
apt-get install -y pigpio

Custom data directory

Your custom setup or rosdep script (see preceding sections) may need some data that is not otherwise accessible. For example, you need to copy some precompiled vendor binaries to a specific location, or provide custom rosdep rules files. For this use case, you can use the option --custom-data-dir to point to an arbitrary path. The sysroot build copies this directory into the build environment, where it's available for use by your custom setup script at ./custom-data/.

Example:

Custom data directory (/arbitrary/local/directory)

/arbitrary/local/directory/
+-- my-data/
|   +-- something.txt

Setup Script (/path/to/custom-setup.sh)

#!/bin/bash
cat custom-data/something.txt

Tool invocation:

ros_cross_compile /path/to/my/workspace --arch aarch64 --os ubuntu \
  --custom-setup-script /path/to/custom-setup.sh \
  --custom-data-dir /arbitrary/local/directory

Now, during the sysroot creation process, you should see the contents of something.txt printed during the execution of the custom script.

NOTE: for trivial text files, as in the preceding example, you could have created those files fully within the --custom-setup-script. But for large or binary data such as precompiled libraries, this feature comes to the rescue.

Tutorial

For a new user, this section walks you through a representative use case, step by step.

This tutorial demonstrates how to cross-compile the File Talker tool against ROS 2 Dashing, to run on an ARM64 Ubuntu system. You can generalize this workflow to any .repos file for your project.

NOTE: this tutorial assumes a Debian-based (including Ubuntu) Linux distribution as the host platform.

Creating a simple source workspace

1. Create a directory for your workspace
   • mkdir cross_compile_ws
   • cd cross_compile_ws
2. Create a .repos file for vcs
   • file_talker.repos

   repositories:
     file_talker:
       type: git
       url: https://github.com/ros-tooling/file_talker.git
       version: master
   

3. Check out the sources to build
   • mkdir -p src
   • vcs import src < file_talker.repos

Running the cross-compilation

ros_cross_compile $(pwd) --rosdistro dashing --arch aarch64 --os ubuntu

Here is a detailed look at the arguments passed to the script:

• --rosdistro dashing

You may specify both ROS and ROS 2 distributions by name, for example, kinetic (ROS) or dashing (ROS 2). ros_cross_compile -h prints the supported distributions for this option

• --arch aarch64

Target the ARMv8 / ARM64 / aarch64 architecture (which are different names for the same thing). ros_cross_compile -h prints the supported architectures for this option.

• --os ubuntu

The target OS is Ubuntu - the tool chooses the OS version automatically based on the ROS Distro's target OS. In this case for ROS 2 Dashing - 18.04 Bionic Beaver.

Outputs of the build

Run the following command

ls cross_compile_ws

If the build succeeded, the directory looks like this:

src/
|-- file_talker/
|-- install_aarch64/
|-- build_aarch64/

The created directory install_aarch64 is the installation of your ROS workspace for your target architecture. You can verify this:

$ file cross_compile_ws/install_aarch64/lib/file_talker/file_talker                                                               0s
cross_compile_ws/install_aarch64/lib/file_talker/file_talker: ELF 64-bit LSB shared object, ARM aarch64, version 1 (GNU/Linux), dynamically linked, interpreter /lib/ld-, for GNU/Linux 3.7.0, BuildID[sha1]=02ede8a648dfa6b5b30c03d54c6d87fd9151389e, not stripped

Using the build on a target platform

Copy install_aarch64 onto the target system into a location of your choosing. It contains the binaries for your workspace.

If your workspace has any dependencies that are outside the source tree - that is, if rosdep had anything to install during the build - then you still need to install these dependencies on the target system.

# Run this on the target system, which must have rosdep already installed
# remember `rosdep init`, `rosdep update`, `apt-get update` if you need them
rosdep install --from-paths install_aarch64/share --ignore-src --rosdistro dashing -y

Now you may use the ROS installation as you would on any other system

source install_aarch64/setup.bash
ros2 run file_talker file_talker my_text_file.txt

License

This library is licensed under the Apache 2.0 License.

Build status

ROS 2 Release	Branch Name	Development	Source Debian Package	X86-64 Debian Package	ARM64 Debian Package	ARMHF Debian package
Latest	master		N/A	N/A	N/A	N/A
Dashing	dashing-devel				N/A	N/A