Hi all- I wrote up an article (or, more like a step-by-step guide) on how to resize the BIOS chip from 8MB to 16MB. This is particularly handy for people (like myself) who want more space for payloads.
This was done on an X210, but theoretically it should work fine on other platforms as well, as long the target chip size is supported by one's chipset.
Feel free to point out any issues or clarifications that need to happen, and don't look at the rest of my site (just kidding, but I haven't really touched it in years and it's horribly out of date).
https://rsend.wordpress.com/x210-coreboot/increasing-rom-chip-size-on-an-x21...
Cheers, Rafael