Mathieu Othacehe

As an embedded software engineer, I'm used to be at the border between software and hardware. However, for many years I delegated everything more complex than finding a GPIO number to a dedicated hardware team.

Now working as a freelance engineer, I've decided to get over the barrier, to be more independent. In this talk, I'll share my journey to the hardware world, from simple hardware designing and routing using free software to more complex design review.

As a big difference between hardware and software is the required equipment, I will also go through the equipment I had to buy and how I use it.

I hope to convey the message that while hardware is a vast world, it is a real advantage for the software engineer to get familiar with a few basic tools of our hardware colleagues.

GNU Guix is a transactional package manager and an advanced distribution based on a minimalistic language: GNU Guile.

While users can choose to build everything from sources, the project is providing binary substitutes. Building and distributing those substitutes is a real challenge, involving a 20 GiB database and more than thirty machines.

In this talk I will present the architecture of the continuous integration system, how it is maintained, the current limitations as well as the possible improvements.

The GNU Guix build farm is composed of more than thirty machines. Most of them are hosted in the same datacenter in Berlin, while others, hosted by individuals are made available through a Wireguard tunnel. Those machines are managed using the GNU Guix deploy mecanism, which will be presented.

The software managing the evaluation and the distributed builds on those machines, Cuirass is also written in GNU Guile. This tool that is obviously relying on GNU Guix will be introduced.

Like most developers, I'm against my will a volunteer system administrator. I take care of my personal and professional notebooks. I also maintain a powerful build server at home and a remote VPS hosting my blog. From times to times I even use a single board computer to host some services.

A few years ago, all those machines ran different, dedicated Linux distributions: Ubuntu, ArchLinux, Debian, Raspbian, making the maintenance a nightmare. That was before diving into GNU Guix.

In this talk, I'll expose how GNU Guix, as an advanced package manager and Linux distribution can be advantageously used on any kind of machine from single board computers to VPS machines.

The declarative aspect of GNU Guix allows to have various operating system definitions inheriting from each other while the associate tooling such as "guix system" and "guix deploy" ease the deployment and upgrade tasks.

This talk demonstrates how to use GNU Guix to build a root filesystem for an embedded device (Pine A64 LTS). I will also try to answer the question: could GNU Guix be a viable alternative to the Yocto project and what would be the benefits of using GNU Guix?

Working as an embedded software engineer, I've been using Yocto and Buildroot projects to create root filesystems for embedded devices. While Buildroot is only suitable for small embedded systems, Yocto does scale well, but is a really complex tool.

Plus, both tools are difficult to handle for developers without a strong understanding of Linux system integration, and on the other hand, do not provide APIs and introspection tools for integrators.

In this talk, I want to explore the possibility of using GNU Guix as an alternative to the Yocto project to generate embedded root filesystems.

With 7 years of existence, more than 10000 packages and 4 supported architectures, GNU Guix can be used as a transactional package manager and an advanced distribution of the GNU operating system running on the Linux kernel.

What would be missing to cover all Yocto features? How could the embedded developer benefit from GNU Guix features such as its high level Scheme API, package substitution mechanism, strong reliability and reproducibility?

To provide some real world application, I'll compare the process of adding support for a new board (Pine A64 LTS) on Yocto and GNU Guix. Then I'll compare how to configure, build and flash a small root filesystem for that same board, on the two tools.