[ronbaby]

I should also have added that yes, I _also_ tried adding the following into my xorg.conf file:

Section "DRI"
Mode 0666
EndSection

That also did not affect the outcome. XBMC is _still_ getting the software rasterizer when run as non-root.

[ronbaby]

NEVERMIND!

I just had not one of those Duh! moments.

Upon spending only a short while digging down into the Mesa source code (and turning on relevant debugging flags and such) it didn't take me that long to realize the root of the problem. Long long ago, I had added the following to my ~/.login file (although I had completely forgotten about this):

# cause gthumb to avoid using dri-7.4.4 (and thus avoid segfaulting)
setenv LIBGL_ALWAYS_SOFTWARE 1

This was, of course, _supposed_ to have been a short term work around for what I had hoped would be a temporary bug in a different application. But I forgot about it entirely, so it just stayed there, and worse, every time I would create a new account for myself on new hardware, I would always copy over my pre-existing ~/.login file, so the xbmc software rasterizer "bug" seemed to follow me around from machine to machine, EXCEPT of course when I would su to root, where the bad env variable setting would no longer apply.

In closing I'll just say thank you to sattia for attempting to be of some assistance, and otherwise, my apologies to all for having needlessly killed so many electrons discussing what proved, in the end, to have been a simple case of pilot error.