Coreboot is an optional open-source firmware to replace the proprietary UEFI/BIOS and AMD has been supporting it since 2011.
According to TechFrog AMD deep throats have suggested that the company’s next-gen products won’t work with Coreboot.
The reason is that one of its key partners in supporting the free software project Sage Electronic Engineering went bust a few months ago. Since Sage closed AMD has slowed down making commits to the project. Certainly the number of changes to the software has dried up since Sage died.
So far Coreboot has been seen on x86-based Chromebooks, Libreboot X200 and T400 (now rebranded Thinkpad X200 and T400, respectively), OLPC XO from the One Laptop per Child initiative, and ThinCan models DBE61, DBE62 and DBE63.
Officially AMD is saying nothing about Zen which is curiously appropriate.