Debugging tools/approach for GPU hangs?

[Jesse Barnes]

On Wed, 23 Sep 2009 15:28:54 -0700
Matt Zimmerman <mdz at canonical.com> wrote:

> On Wed, Sep 23, 2009 at 01:27:09PM -0700, Jesse Barnes wrote:
> > On Tue, 22 Sep 2009 09:41:45 -0700
> > Matt Zimmerman <mdz at canonical.com> wrote:
> > > I had a look at this recently and couldn't quite figure out how to
> > > match the uevent.  The relevant code seems to be in
> > > drivers/gpu/drm/i915/i915_irq.c:i915_capture_error_state et al,
> > > but it's not obvious how to match that kobject in a udev rule.
> > > Can you give me a hint?
> > 
> > You should get a uevent from the i915 drm device (udevadm will show
> > hotplug events when you plug/unplug VGA; you can use them as an
> > example).
> > 
> > You'll get three events, one when the error is detected, one before
> > the reset and one after.  Each has a different environment variable
> > set; the initial error has ERROR=1, the pre-reset event has RESET=1
> > and the post-reset event has ERROR=0.
> > 
> > Does that help?
> 
> Yes, that's exactly what I was looking for, thanks.
> 
> I assume we should get the dump after the error and before the reset?

Yeah, if you can capture it at the first ERROR=1 event it might be
helpful.  Capturing state after the reset probably isn't necessary.

Jesse