Created attachment 120655 [details]
gdb backtrace from xorg when system locks up during glretrace replay

Thanks Nicolai and others for looking into this. I have some good news.

The apitrace developer patched glretrace, so that it no longer crashes duri=
ng
replay. He says it's a bug inside XCOM. He also says the problem might like=
ly
cause the radeonsi driver crash as well. See his comment here:
https://github.com/apitrace/apitrace/issues/407#issuecomment-166619=
366

(If this indeed turns out to be an XCOM bug, it would be nice if we could p=
ut
some safeguards into the driver and didn't crash for invalid commands, but =
I'm
saying that as someone who knows exactly zero about gpu driver programming).

Also, now that glretrace does not crash, I'm able to easily loop the trace
until its very end. In just a handful of replays, my system locked up 3 tim=
es.
I haven't seen all lockups, but at least once it occurred exactly at the po=
int
where the lockup occurred while recording (at the very end). So it seems I'm
able to reproduce this with reasonable likelihood, and therefore can test s=
ome
fixes if needed.

(In reply to Michel D=C3=A4nzer from comment #77)
> No need, it's not important. The assumption for =
now is that the Xorg crash
> is caused by the GPU hang. If you happen to get a gdb backtrace of it =
in the
> future, that will help verify this assumption, but it's no more than n=
ice to
> have.

I have it now, attaching.