Bug#336997: xlibmesa-dri: having issues with driver not claiming to support visuals

[Timothy Talbot <tim@hockerley.freeserve.co.uk>]

I'm having similar problems with a G450
It was crashing erratically as described til today (12th Feb), when xorg-x11 
6.9.0 arrived in testing. Now it doesn't work at all (direct rendering has 
been disabled). The relevant parts of Xorg.0.log:

(II) MGA(0): Using overlay video
(II) MGA(0): X context handle = 0x1
(II) MGA(0): [drm] installed DRM signal handler
(II) MGA(0): [DRI] installation complete
(EE) MGA(0): [drm] Failed to map DMA buffers list
(II) MGA(0): [drm] removed 1 reserved context for kernel
(II) MGA(0): [drm] unmapping 8192 bytes of SAREA 0xd0a3d000 at 0xb615f000
(WW) MGA(0): Direct rendering disabled

Hope this in some way helps, I've never managed a working DRI.