self modifying code in intel vga bios?

Fish- has catched this on a Intel(r)915GM/910ML/915MS Graphics Controller
with realemu:

bad mem write c0c11
bad memory access
1d17b0 4a008800 00000002 00000000 0000a002 00009000 00005108 ac007bda 00007bc0 0000 0000 0000 c000 csZoPdI 61ed c6 MOV CS:[c11], $01

question to the coreboot guys:

did you ever see the bios writing in the rom area?

i found this quote on: http://www.coreboot.org/VGA_support

"Even if your VGA BIOS uses self-modifying code you get a correct image"

i know that the rom area is usualy cached in ram but to catch mistakes
i disallow writing to the rom area...  fish will make full traces
later this day...  it could be just a screwup on my side...
just curious :)

[Georgi, Patrick]

Am Dienstag, den 08.03.2011, 10:28 +0100 schrieb [e-mail]:
> i know that the rom area is usualy cached in ram but to catch mistakes
> i disallow writing to the rom area...  fish will make full traces
> later this day...  it could be just a screwup on my side...
> just curious :)

I saw Intel VGABIOSes write to that area, and it was required for proper
operation of the device later. See r6251 of coreboot where I changed
YABEL's behaviour to account for that.

Regards,
Patrick

[Joseph Smith]

O.T. - Is there i915 development going on?

On Tue, 8 Mar 2011 11:01:57 +0100, "Georgi, Patrick"
 wrote:
> Am Dienstag, den 08.03.2011, 10:28 +0100 schrieb [e-mail]:
> > i know that the rom area is usualy cached in ram but to catch mistakes
> > i disallow writing to the rom area...  fish will make full traces
> > later this day...  it could be just a screwup on my side...
> > just curious :)
>
> I saw Intel VGABIOSes write to that area, and it was required for proper
> operation of the device later. See r6251 of coreboot where I changed
> YABEL's behaviour to account for that.