https://bugs.freedesktop.org/show_bug.cgi?id=31052
--- Comment #1 from Chris bitbytebit@gmail.com 2010-10-22 15:50:05 PDT --- Created an attachment (id=39640) --> (https://bugs.freedesktop.org/attachment.cgi?id=39640) The bios of the AVGA3000 (radeon 2600 RV630) card
This may help, this is the bios of this card which is modified to hold modelines that are custom made for an arcade monitor. I think there's more modified though than just that, since the radeon drm driver in KMS hits a null pointer and crashes.