[coreboot] [PATCH] Free VGA BIOS for K8M890

Rudolf Marek r.marek at assembler.cz
Sat Apr 25 16:01:09 CEST 2009

Hash: SHA1


I managed to catch all I/O for init of K8M890 IGP. Attached patch is for
http://www.nongnu.org/vgabios/. With a patch one can have a console and some VGA
resolutions also might work.

It is just a interesting result.

I used libx86 library to catch all IO. It was quite painful until I realize that
the emulator cannot handle properly opcodes like

0x66 0xe8 .. .. 0xff 0xff and also mov al,cs:[ebx] which  I get caught in Sebios
int 15 routine.

I somehow  managed to fix the emulator (only hacks) and patched the IO backend
of emulator and obtained following tracedump:

OUTB to 3c3 is 1
OUTW to 3c4 is 32
OUTB to 3c4 is 10
INB from 3c5 is 0
OUTB to 3c5 is 1
OUTL to cf8 is 80010000
INL from cfc is 32301106
OUTB to 3c4 is 2d
INB from 3c5 is aa
OUTB to 3c5 is bf
OUTW to 3c4 is 816
and other ~250 lines

Those were just directly transformed with bash script to IO calls in patch. The
BIOS works, it even sets the memory speed grade, but not the mem size to scratch
registers (it uses SeaBIOS VIA vga hooks for this)

I can boot X without any problems, Windows 7 boots with VGAfailsafe driver and
16 colors ;)

If someone ever want to write somethink like SeaBIOS but for VGA here is the
chance (I dont have time :/)

What is important, some bits in this init fixes also the problem with PowerNow
which I had until VGA option rom was run. There must be smth set which enables
the HT deliver stop grants or smth like this again.

Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

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