[coreboot] vm86 for gigabyte m57sli

Ronald Hoogenboom ronald at zonnet.nl
Mon Mar 10 23:52:35 CET 2008


In my quest to get some life in my nvidia 8600GT board, I've been trying
to get the VGA rom executed by vm86 instead of x86emu.
There are a few other mainboards that do this too. The source file
implementing this turns out to be called 'vgabios.c', of which some
variants exist. I also figured out that the _RAMBASE must be set to
0x4000 for this to be linkable (otherwise truncated 16 bit relocations).

The one for via epia-m needs some support in the northbridge (vt8623) to
call the do_vgabios. The vgabios file is in the mainboard/via/epia-m

The one for artecgroup dbe61 seems to be the most stand-alone/versatile,
but it needs some modification of the device tree in Config.lb. The
vgabios.c is in mainboard/artecgroup/dbe61/realmode and it looks like
the intention is that this directory should be copied under drivers/pci
and some section

chip drivers/pci/realmode
   device pci 1.1 on end                   # VGA
   register "rom_address" = "0xf4100000"   # at the beginning of 256k

should be added to the Config.lb of the mainboard. But I cannot figure
out where it should be exactly. Putting it just after the 'end # PCI
domain' will just make the boot stops in 'Reading resources' without any
clue. Putting it just before the 'end # PCI domain' produces 'PCI: Left
over static devices....' in 'Enumerating busses'.
Also setting the rom address in there like this looks awkward to me, as
it will most probably be different for a different VGA card.

What is the way to go forward? Would I be better off using the epia-m
vm86 and change the northbridge for the m57sli (amdk8)?


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