Comment # 21 on bug 55692 from Alexandre Demers

(In reply to comment #19)
> (In reply to comment #18)
> > Is VM enabled or disabled on your system? I'm experiencing a similar bug
> > with kernel 3.7-rc1, but it is working fine with 3.6. VM is enabled on my
> > system, I'll try to disable it when I'll get home to see if that helps and
> > I'll also try to bisect the kernel commit that screwed things for me.
> 
> I don't know, how can i check?

Use "setenv" in a terminal and look for "RADEON_VA".