[coreboot] SeaBIOS and CBFS

[Kevin O'Connor]

Hi,

The latest seabios git now supports reading option roms from the CBFS
flash layout.

To enable it in SeaBIOS, modify src/config.h and make sure the
following are set:

#define CONFIG_COREBOOT 1
#define CONFIG_OPTIONROMS_DEPLOYED 0
#define CONFIG_COREBOOT_FLASH 1

It will also be necessary to enable support in coreboot (modify
Config.lb and add "option CONFIG_ROMFS=1").  The current support just
takes raw files, and it does not support compression.  To add a rom,
use the following:

./romtool coreboot.romfs add vgabios.bin pci1013,00b8.rom 0

Where "vgabios.bin" is the rom file to add and "pci1013,00b8.rom" is
the cbfs name - get the proper vendor/deviceid from lspci.  Any number
of roms may be added.

I've tested this on qemu (with a vga rom) and on epia-cn (with vga and
gpxe).

-Kevin