https://bugzilla.kernel.org/show_bug.cgi?id=37442
--- Comment #4 from Wolfram Sang w.sang@pengutronix.de 2011-06-15 07:38:53 --- KMS works now, was a kernel misconfiguration (forgot to disable radeonfb, doh!). Interestingly, KMS does work with AGP4x while the Xorg driver can just handle AGP2x (also freezes the machine otherwise). Original bug still stands; checked the faulty commit but couldn't spot anything.