dri on radeon mobility 7500

[Steve Franks]

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
....

Steve