(In reply to comment #19)
> If I followed you correctly, setting bit 24 to "1" disables memory but keeps
> the CRTC state as it is (hopefully in sync with the monitor). However, what
> I see when grub2 kicks in with the "gfxpayload=keep" is an unsynced monitor.
> Sometimes the display will be black, other times it will only appear in the
> first couple of vertical lines, in others it will be vertically synced but
> shifted to the right at half or at two third of the screen. In other words,
> this really seems to be a sync problem. Should I try to combine patch 69113
> and patch 69370 with the others?

Are you saying the monitor gets messed up when grub kicks in?  I.e., before the
OS loads?  If so, that sounds like a grub issue.