Can I put coreboot into a PCI expansion ROM?
There’s little use in doing that, as a lots of initialization has already been done by the proprietary BIOS (or coreboot) by the time the PCI expansion ROM is executed. It won’t be possible to run coreboot from a PCI expansion ROM after a proprietary BIOS has already been running for instance. Note: The Intel ICH7 southbridge seems to allows booting from PCI ROMs (not arbitrary PCI expansion ROMs as used on graphics cards, SCSI controllers, etc.) — maybe this should be investigated in order to check if or how it might be useful.