Comment 46 for bug 404064

I seem to have this problem too, using Thinkpad with Intel 852/855 card.

running this:
LIBGL_DEBUG=verbose glxinfo | grep error
outputs this:
libGL: OpenDriver: trying /usr/lib/dri/tls/i915_dri.so
libGL: OpenDriver: trying /usr/lib/dri/i915_dri.so
libGL error: failed to open drm device: Permission denied
libGL: OpenDriver: trying /usr/lib/dri/tls/swrast_dri.so
libGL: OpenDriver: trying /usr/lib/dri/swrast_dri.so

command:
glxinfo | grep rend
output:
direct rendering: Yes
OpenGL renderer string: Software Rasterizer

but rootish command:
sudo glxinfo | grep rend
gives this:
direct rendering: Yes
OpenGL renderer string: Mesa DRI Intel(R) 852GM/855GM GEM 20090712 2009Q2 RC3 x86/MMX/SSE2

user glxgears fps: about ~530
root glxgears fps: about ~1400

Why can root render with the proper drivers and user not?