dri on radeon mobility 7500

[Tijl Coosemans]

On Wednesday 23 January 2008 05:20:33 Steve Franks wrote:
> I get the infamous "Xlib:  extension "XFree86-DRI" missing on display
> ":0.0" error on my new system (7.0rc1).  I've put dri & glx in
> xorg.conf (7.3), to no avail.
> 
> Relevant dmesg:
> ...
> drm0: <ATI Radeon RS100 Mobility U1> on vgapci0
> info: [drm] AGP at 0xe4000000 64MB
> info: [drm] Initialized radeon 1.25.0 20060524
> ...
> info: [drm] Setting GART location based on new memory map
> info: [drm] writeback test succeeded in 1 usecs
> drm0: [ITHREAD]
> error: [drm:pid1180:drm_close] *ERROR* can't find authenticator
> ....

Some obvious problems I can think of:

Do you have something like this in xorg.conf:

Section "DRI"
        Mode    0660   # Set permissions on drm device
EndSection

And, do you actually have dri drivers installed (graphics/dri port)?