https://bugs.freedesktop.org/show_bug.cgi?id=84627
--- Comment #31 from Michel Dänzer michel@daenzer.net --- (In reply to Zbigniew Luszpinski from comment #30)
Just apply only one of these solutions. I prefer to add my GPU to exclusion list "drm/radeon: Ignore RADEON_GEM_GTT_WC on Kabini" patch instead of patching mesa.
While that patch works around the problem, it doesn't make much sense conceptually: Since everything is working fine with 64-bit kernels, there doesn't seem to be anything wrong with any particular GPUs.
Also, disabling write-combining decreases performance.
For those reasons, until someone figures out the root cause of this problem, IMHO the preferred workaround is to run a 64-bit kernel. Any particular reason why you can't do that?