I installed drm and mesa from git, and now it works! (once I also enabled EXA in xorg.conf).
The only problem is that there is some horizontal tearing in video playback. Not worse than fglrx has, mind you (and in fglrx the tearing is diagonal). Is there a fix for this?
FWIW, things seem to be somewhat improved with my latest commits. Textured video seems to work ok without the drm now, but EXA render still has issues if the drm isn't loaded.
Can someone point me to instructions on building/installing the radeon driver?
this should give you the basics:
http://www.botchco.com/agd5f/?page_id=2