[Intel-gfx] Reporting GPU hung bugs

[Geir Ove Myhr]

Hi everyone,

Since around kernel 2.6.30 we have asked [1] anyone reporting a freeze
bug (GPU hung) in Ubuntu to get a batchbuffer dump so that we could
include that in the upstream bug report at freedesktop.org. We're
seeing quite a lot of these bugs nowadays, especially on 845G, 855GM,
and 945G chipsets, but also on newer ones. On one of the fdo bug
reports, Chris Wilson said [2]:

> Sorry Geir, ever since hang check started resetting the gpu on hangs we've lost
> the utility of dumping, the dumps you have captured contain no information. :(

Since my questions are general, I found it more appropriate to ask
here than on the bug report:
- In which kernel was gpu-resetting enabled?
- Is it possible to disable gpu-resetting for troubleshooting purposes?
- If not, would it be useful for you to have batchbuffer dumps from
the last kernel without gpu-resetting? (The next Ubuntu will ship with
kernel 2.6.32, but we have had people getting batchbuffer dumps with
the latest 2.6.33-rcX in order to have up-to-date software)
- What should we ask bug reporters for in order to generate useful,
high-quality bug reports for this kind of bugs?
- If you still care about batchbuffer dumps, which of the xorg.conf
debug options DebugFlushBatches, DebugFlushCaches, DebugWait would you
like to have enabled? (I have been asking for DebugFlushCaches lately,
since reading this [3] from Albert Damen)

There are a lot of users who are willing to break their xorg in new
and interesting ways in order to help troubleshooting, but we need
some guidance in order for that effort to be useful.

[1]: https://wiki.ubuntu.com/X/Troubleshooting/Freeze#How%20to%20Get%20a%20Batchbuffer%20Dump%20(-intel%20only)
[2]: http://bugs.freedesktop.org/show_bug.cgi?id=26333#c5
[3]: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/447892/comments/23

Geir Ove