[coreboot] 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 :)