https://bugs.freedesktop.org/show_bug.cgi?id=30227
--- Comment #4 from DaNiMoTh kronat@tiscali.it 2010-09-16 12:00:25 PDT --- (In reply to comment #3)
Does radeon.agpmode=1 or radeon.agpmode=-1 help?
This happens with radeon.agpmode=-1 on the kernel boot command line. Without it, the kernel doesn't boot (it freeze, without eth connection and monitor freeze on some openfirmware specification - I have no serial - when switching from openfirmware to kernel itself, I think).