[Intel-gfx] [PATCH igt 3/9] igt/drv_hangman: Inject a true hang

[Chris Wilson]

On Wed, Dec 16, 2015 at 03:12:57PM +0200, Ville Syrjälä wrote:
> On Wed, Dec 16, 2015 at 10:37:55AM +0000, Chris Wilson wrote:
> > On Wed, Dec 16, 2015 at 10:02:27AM +0100, Daniel Vetter wrote:
> > > On Sat, Dec 12, 2015 at 08:02:49PM +0000, Chris Wilson wrote:
> > > > Wean drv_hangman off the atrocious stop_rings and use a real GPU hang
> > > > instead.
> > > > 
> > > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > > 
> > > Doesn't this kill pre-gen6? Or at least anything where we don't have
> > > proper hang recovery ... Lack of that is why I've done the original
> > > stop_rings fun.
> > 
> > Originally, igt_hang_ring required gen >= 5, but since that Ville has
> > been working hard on getting reset support working for gen3 and gen4,
> > now we query the kernel as to whether it can reset the device. So by
> > switching over we lose testing of simulated hangs and recovery code (or 
> > KMS handling during wedged) for gen2.
> > 
> > It is a loss in test coverage, but the benefit is that we can remove the
> > hang injection code from the kernel. And that is a tradeoff I am willing
> > to make.
> 
> One day I will get around to trying D3 as a reset mechanism for gen2 ;)
> Until then, losing the gen2 test coverage seems fairly reasonable.
> I suppose the only thing it's really testing on gen2 is making sure we
> don't lock up or oops when the gpu hangs.
> 
> So what might be nice is a way to force the hang tests to run even 
> when gpu reset isn't supported, just to make sure the system doesn't
> die completely. Obviously it's going to be slow to run such tests due
> to needing a reboot between every test, but it would be enough to do
> an occasional spot check to see if there's been a regression.

Would "export IGT_HANG_WITHOUT_RESET=1" be enough?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre