coreboot

Patrick Georgi wrote:

SeaBIOS requires the CBFS master header to find the start address of the CBFS structure. It should parse the FMAP instead.

The coreboot tables have lb_boot_media_params which should allow to use that offset as the base of the active cbfs. Then it should search for the first LARCHIVE just as coreboot does.
Using the "cbfs master header" can be left as a fallback option such that newer SeaBIOS revision work with very old coreboot releases (fb5d5b16eef66d37dc20cdf0769c9049bf47d6be added this coreboot table entry in 2015).
Or maybe it is acceptable to not use a 2021 payload on a 2015 coreboot build?