Cross-compile Program for Raspbian

“Hello, Raspbian from a more capable build machine!\n”

Table of Contents

1. Table of Contents
2. Overview
3. Cross-Compilation Toolchain Selection
4. Environment/Project Setup Procedure
5. Building The Project
6. Resources
7. To-Do

Overview

Goal is to set up a cross-compilation environment on an Ubuntu-based machine and build a “Hello, world!” CMake project for the target.

Setup used for testing is -

Component	Value
Build OS	Ubuntu 20.04 LTS
Target OS	Raspbian Buster Lite, February 2020
Target platform	Raspberry Pi 3 Model B

Cross-Compilation Toolchain Selection

Here, the main point is to obtain the cross-compilation toolchain for RPi. The important thing is that this toolchain produces binaries which are compatible with the execution environment. This is a topic to be covered, but for now following toolchains will work:

Source	GCC version	Source
toolchain_rpi	4.9.3	Raspberry Pi Foundation
toolchain_pro	8.3.0	Alternative build by Pro

Notes:

1. RPi repo has several toolchains. Select one per this article.

Environment/Project Setup Procedure

1. Checkout this repo with test CMake projects - GitHub link.
2. Set up the RPi test project per its readme.

Building The Project

1. Run configure/build for CMake (<project>/build$ cmake .. && make).
2. Built binaries are in CMake subproject subdirectories.
3. We can verify they have been cross compiled by running file -

   <project>/build/hello-raspbian-cross-pi-gcc$ file HelloRaspbianCrossPiGcc 
   HelloRaspbianCrossPiGcc: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, for GNU/Linux 3.2.0, with debug_info, not stripped
   

Resources

• toolchain_rpi : Overview of MCU and the ESP32-based boards.
• toolchain_pro : Page with pretty much everything on ESP32.
• hello-vscode-cmake : Repo with test CMake project.
• pro-toolchain-build : Article on building a GCC toolchain for RPi.
• cmake-cross-compile : How to setup CMake project for cross compilation.
• deardevices_rpi-cross-compile : How to setup RPi provided toolchains.

To-Do

1. Checklist for toolchain suitability for the given target.