Yocto project and OpenEmbedded training updated to Krogoth


Continuing our efforts to keep our training materials up-to-date we just refreshed our Yocto project and OpenEmbedded training course to the latest Yocto project release, Krogoth (2.1.1). In addition to adapting our training labs to the Krogoth release, we improved our training materials to cover more aspects and new features.

The most important changes are:

  • New chapter about devtool, the new utility from the Yocto project to improve the developers’ workflow to integrate a package into the build system or to make patches to existing packages.
  • Improve the distro layers slides to add configuration samples and give advice on how to use these layers.
  • Add a part about quilt to easily patch already supported packages.
  • Explain in depth how file inclusions are handled by BitBake.
  • Improve the description about tasks by adding slides on how to write them in Python.

The updated training materials are available on our training page: agenda (PDF), slides (PDF) and labs (PDF).

Join our Yocto specialist Alexandre Belloni for the first public session of this improved training in Lyon (France) on October 19-21. We are also available to deliver this training worldwide at your site, contact us!

Experiment with Yocto

I recently had the opportunity to use Yocto. I already practiced quite a lot with OpenEmbedded before. You can see Yocto as a project derived from OpenEmbedded even it is a bit more than that.

In fact, Yocto is made of Poky (a build system based on OpenEmbedded), a few added build tools (swabber, pseudo, etc.), as well as a set of meta data allowing to create embedded distributions for a number of targets.

The strength but also the weakness of OpenEmbedded is that it a very flexible build system. It can make production root filesystems, but also a complete distribution with its ready to use package repository, and this for multiple hardware platforms. It makes it a difficult system to get started and get efficient with. Even two years ago, the OpenEmbedded documentation contributed to making it difficult to get started. Indeed, OpenEmbedded did supply some documentation, but which only started to make sense once you start mastering it. This is quite a paradox for a piece of documentation. It lacked the elements allowing developers to understand its operation well.

With Yocto, I was pleased to realize that substantial progress had been made on this side. The project comes with documentation that is much more exhaustive and above all much more accessible for beginners. Getting started with it is still not completely straightforward, but this time, this is rather because of the complexity and the rich features of the tool.

In a few hours, I managed to develop a minimalistic BSP (Board Support Package) for a given board (in this case a AT91SAM9G20-EK). The concept of layer allows to have a configuration layer specific to a given piece of hardware. You can even support multiple hardware platforms at once and add specific packages. A layer is indeed just a set of packages and configurations (or configuration overrides). The BSP is just a layer specific to one or several pieces of hardware.

As you can see, even to support a simple embedded board, there is already a number of concepts to deal with. There are also multiple ways of achieving the same result but which will be easier or more difficult to maintain. The concept of “BSP” for Yocto is therefore a kind of guideline to allow the Yocto community to have a common point of reference. I will try to illustrate the use of a BSP on the AT91SAMG20-EK board here and/or on my Google+ page.

Another significant progress is optimizing build time for a “minimalistic” target, which went down from more than three hours to just over one hour now. It remains a long time for a very simple target.

To build a filesystem image with only a few components, Buildroot remains much more appropriate. For systems that require a great number of components, more advanced functionality is then often needed, such as managing a package repository and supporting multiple hardware platforms at once for example. In this case, Yocto remains the best (the only?) option, all the more as this project addresses the traditional weaknesses of OpenEmbedded.