Setting up the Linux operating system

In principle, you can use any Linux-based operating system as long as it comes with the required dependencies to run EVerest.

We strongly recommend using Yocto as it has some advantages over other distributions:

  • It can be set up to do reproducible builds with versioning.

  • Most CPUs and SoMs already come with Yocto board support packages (BSP).

  • EVerest comes with full support for selected Yocto long term support releases (LTS) (scarthgap as of the time of writing).

  • It can be nicely integrated with your CI/CD to build complete production images and update packages.

  • It provides a software bill of materials of all packages in the Linux system for managing licenses.

  • Broad community

  • Automatic generation of cross-compile toolchains, that can be used during the development phase.

You can find more information about the Yocto project here: https://www.yoctoproject.org

Warning

Setting up the Linux base system for your product is a quite complex task that should be performed by domain experts. In case you do not have experts in your team, consider getting help from a company specialized on this.

The end product’s reliability, security and user experience strongly depends on a sound architecture, implementation and maintenance strategy of the base Linux system. This should not be underestimated.

Covering all aspects of setting up a Linux base system is out of the scope of this documentation, but we would like to give some examples and ideas and point out some typical solutions to questions you will have on your journey. Do not consider this complete!

Setup a Yocto build environment

Yocto has comprehensive caching capabilities that mean build times are substantially reduced for successive builds. However an initial build will take hours since initial versions need to be fetched and built so that caches are populated. There is support for sharing downloads and caches that can reduce build times and are worth considering where you have a co-located team.

A good build machine will have lots of RAM, SSD storage and multi-core processor as well as a fast Internet connection.

It is possible to use a high-performance laptop especially for incremental builds once the initial build is complete.

Warning

Running this inside of a virtual machine is not recommended.

A full Yocto build easily requires 50-100 GB of disk space, and it will use multiple cores. So, make sure you have enough RAM per core (e.g. 2-3 GB per (hyperthread) core).

Install a Linux distribution supported by Yocto and install all necessary dependencies. See here for more information about that:

https://docs.yoctoproject.org/ref-manual/system-requirements.html

Alternatively, consider building in a container. Once you move to production, a build container will probably be needed anyway to build images in your CI/CD.

It is also recommended to archive the containers to be able to do fully reproducible builds of older versions in the future.

Yocto itself can produce builds that are completely tagged (i.e. each source package is tagged with a fixed version or Git hash), so they are in principle reproducible.

There are - however - a few build dependencies to the host system that may prevent you from building your released 1.0 version in ten years from now. As an example, the Python version in ten years from now may not run the old bitbake correctly anymore. Also, the Yocto recipes contain only download URLs and version tags, but not the source packages itself.

Let’s start with an example and set up the Yocto build environment that we use for EVerest on the BelayBox hardware.

Building the BelayBox Yocto image

An example can be found here for the BelayBox:

https://github.com/PionixPublic/belaybox-yocto

Check out the README in this repository on how to build and install this Yocto on the BelayBox.

Authors: Cornelius Claussen, Manuel Ziegler