Starting SEABIOS as Grub payload and NOT loading roms/configuration from CBFS

[Dennis Guse]

Hey,

I know usually Seabios is loaded by Coreboot and then Seabios loads
its modules from CBFS.
I want to do it slightly different:
* Hardware starts coreboot (actually libreboot flashed to a Lenovo X60)
* Coreboot starts Grub2
* Grub2 chainloads Seabios from external storage, e.g., USB0:
`chainloader (usb0,msdos1)/bios.bin.elf`
* Seabios starts and loads its roms and configuration NOT from CBFS

My actual reason for not accessing CBFS is that I want to avoid
flashing the CBFS to hardware for every change of Seabios or its
configuration.
However, I want to have VGA output...

So far, I can chainload Seabios from Grub2 (mostly via USB0).
Then Seabios is accessing the CBFS and automatically loads Grub2 from CBFS.

For my case, it would be perfect if the roms (mainly VGA.rom) and
configuration would be compiled into the `bios.bin.elf`.

I looked into the source and did not find a built in option for this
(I think nobody ever came with such a use case).
What would be a good starting point for me?

Best,
---
Dennis Guse