X Server lockups happen every now and then with the dmesg output:
[ 614.220903] [drm:i915_gem_execbuffer] *ERROR* Execbuf while wedged
[ 614.432038] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer elapsed... GPU hung
[ 614.432058] render error detected, EIR: 0x00000000
[ 614.432068] i915: Waking up sleeping processes
[ 614.432125] reboot required
I can still move the mouse, switch to console works, but even restarting X leaves the screen black.
Manually "unwedging" does not help.
Referring to #14627, CONFIG_DMAR is disabled.
To me this seems to be related to Archlinux bug 17705: http://bugs.archlinux.org/task/17705
Hardware: intel 945GM
Probably a dupe of bug #15004 (but thanks for CC'ing me Johannes :))
Thanks for the hint, Colin. As Tom did not comment in the other bug, I assumed there was none yet.
*** This bug has been marked as a duplicate of bug 15004 ***