[ubuntu-x] Intel GPU hangs and batchbuffer dumps

[Bryce Harrington]

On Fri, Feb 19, 2010 at 12:21:21PM +0100, Geir Ove Myhr wrote:
> On Fri, Feb 19, 2010 at 3:55 AM, Bryce Harrington <bryce at canonical.com> wrote:
> > I guess we need more than just the gpu dump, but this at least gives a
> > starting point.
> 
> We used to collect /sys/kernel/debug/dri/0/i915* as well. I don't know
> what the different files really means, but I think i915_regs contains
> the same information as the output of intel_gpu_dump and has been
> removed in recent kernels since reading it from debugfs sometimes
> caused GPU hangs [1].

Mm, ok in that case I don't want to blindly copy all the files there.
At least i915_error_state looks useful so I'll start with that.  As
we see upstream requesting other files on these kinds of bugs we can add
to the list (just let me know).

I did not see anything on intellinuxgraphics.org about particular files
they want.  In our own freeze troubleshooting guide, only
i915_error_state is mentioned.

> With the patch from Chris Wilson, it should be sufficient to capture
> only the file i915_error_state, but I guess we have to get the timing
> right. The udev rule is only triggered when the kernel notices that
> the GPU is hung, right? At that time the GPU is reset and this is
> probably also the time that i915_error_state shows up. So I'm
> wondering if we currently end up with recording a GPU dump of a
> reinitialized GPU, which is not very useful. Maybe this would have
> been obvious to me if I knew how to read the output of
> intel_gpu_dump...

Yeah I've been wondering this myself...

Jesse, here are a few examples of the dumps we're collecting now.  Mind
doublechecking that this are actually useful dumps?

 https://bugs.edge.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/529702
 https://bugs.edge.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/529410
 https://bugs.edge.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/528795

Bryce