The industry-standard way of creating firmware support for a new SoC is to start with a copy of the code from the previous SoC generation and then make the changes needed to work for the new SoC generation. While this has some advantages, it might also result in code being copied over that might no longer be applicable to the new SoC.
When developing the coreboot support for the Cezanne APUs, we took another approach that was suggested by a member of the coreboot community and built the new SoC firmware support in coreboot starting with an empty directory and added the needed functionality in small pieces. In this talk, I will present our experience with this approach, the advantages and disadvantages it has, what we learned from doing this, and in which cases this new approach might be the preferred one.