On my Suse9.0 box whether I get 3D enabled when X starts up seems be a bit random. Sporadically, (more common on an X restart than the first X boot) 3D will be disabled. When this happens I get the following info on /var/log/XFree86.0.log
(II) MGA(0): [drm] drmSetBusid failed (9, PCI:1:0:0), Device or resource busy (EE) MGA(0): [drm] DRIScreenInit failed. Disabling DRI.
I'm running a matrox G400 card.
this may help: http://lists.debian.org/debian-user/2001/debian-user-200106/msg01004.html
Another curious aspect of the 3D behaviour is that when it does work, on full screen mode it will change the monitor timings to the point that my monitor will complain their out of range. The monitor will still display, but there is this nasty on-screen-display right in the middle, complaining that the frequency is out of range. Annoyingly there doesn't seem to be way of getting rid of it, so playing a game is a bit tricky. So does anybody know if there is a way of settings the timings for full screen 3D display?
Check the previous message(s) in the thread linked above for more G400 config info.
HTH Syd