https://bugs.freedesktop.org/show_bug.cgi?id=28217
--- Comment #7 from Alex Deucher agd5f@yahoo.com 2010-05-24 11:13:58 PDT --- Are you trying to use ums rather than kms? You need to disable kms if you want to use ums. (boot with radeon.modeset=0). If you want to use kms, the drm must be loaded before starting X.