Created attachment 104682 [details]
full backtrace

For people who are part of the Closed Alpha and want to test: It doesn't happen
when changing the shadow levels between active levels.
But when changing shadows from off to any level or from any level to off, this
segfault happens every time.

00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor
Graphics Controller (rev 09)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI]
Wimbledon XT [Radeon HD 7970M] (rev ff)

It does not crash when I run it on intel. It also does not crash when I run it
on llvmpipe.

So it is possibly related to PRIME rather than radeonsi, unfortunately I can't
test without PRIME.

mesa git, linux 3.16, launched in steam with:
DRI_PRIME=1 GALLIUM_HUD="fps,VRAM-usage+GTT-usage" %command%
It happens with both dri3 offloading and with LIBGL_DRI3_DISABLE=1