Created attachment 111507 [details]
Xorg log, dmesg | fgrep radeon, and glxinfo with LIBGL_DEBUG set

I have a PowerPC G5 (ppc64 with 64-bit userland) with working KMS using a
(ostensibly x86) Radeon HD4650. KMS is enabled and the kernel and Xorg parts of
KMS/DRI2 appear to be attaching correctly.

After X starts, running LIBGL_DEBUG=verbose glxinfo outputs the following:
libGL: OpenDriver: trying /usr/lib64/dri/tls/r600_dri.so
libGL: OpenDriver: trying /usr/lib64/dri/r600_dri.so
libGL: driver does not expose __driDriverGetExtensions_r600():
/usr/lib64/dri/r600_dri.so: undefined symbol: __driDriverGetExtensions_r600
libGL: Can't open configuration file /root/.drirc: No such file or directory.
libGL: Can't open configuration file /root/.drirc: No such file or directory.
libGL error: failed to load driver: r600
libGL: OpenDriver: trying /usr/lib64/dri/tls/swrast_dri.so
libGL: OpenDriver: trying /usr/lib64/dri/swrast_dri.so
libGL: driver does not expose __driDriverGetExtensions_swrast():
/usr/lib64/dri/swrast_dri.so: undefined symbol: __driDriverGetExtensions_swrast
libGL: Can't open configuration file /root/.drirc: No such file or directory.
libGL: Can't open configuration file /root/.drirc: No such file or directory.
libGL error: failed to load driver: swrast
Error: couldn't find RGB GLX visual or fbconfig
Error: couldn't find RGB GLX visual or fbconfig

I am under the impression that the undefined symbol should not be causing
problems after reading this bug: 
https://bugs.freedesktop.org/show_bug.cgi?id=72198

Nonetheless, glxgears will not run, and in general it appears mesa acceleration
is not occurring. Mesa was compiled with support for llvm and the r600
generator.
I am attaching various logs. I would be glad to test patches or hacks :)