[Intel-gfx] [PATCH] drm/vgem: Allow root to inject hanging fences onto dmabufs

[Daniel Vetter]

On Fri, Nov 18, 2016 at 08:49:37AM +0000, Chris Wilson wrote:
> On Wed, Jul 20, 2016 at 08:39:43PM +0100, Chris Wilson wrote:
> > When performing driver testing, one factor we want to test is how we
> > handle a foreign fence that is never signaled. We can wait on that fence
> > indefinitely, in which case the driver appears hung, or we can take some
> > remedial action (with risks regarding the state of any shared content).
> > Whatever the action choosen by the driver, in order to perform the test
> > we want to disable the safety feature of vgem fence (which is then used
> > to test implicit dma-buf fencing). This is regarded as a highly
> > dangerous feature and so hidden behind an expert config option and only
> > available to root when enabled.
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> 
> Ping. This is invaluable for my testing (some tests are impossible
> without it).

Hm, I thought I voted for a module option (so that tests can frob at
runtime) that auto-taints the kernel. And then maybe always allow it. I
just don't like when Kconfig settings can result in testcase skips, makes
it uncertain whether QA did QA or not.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch