Quoting Ewelina Musial (2018-04-11 11:20:56)
> On Wed, Apr 11, 2018 at 09:48:21AM +0100, Chris Wilson wrote:
> > Quoting Ewelina Musial (2018-04-11 09:27:12)
> > > Test have similar functionality that gem_cs_prefetch IGT test
> > > but gem_cs_prefetch is not up to date and there was an idea
> > > to move this test to kselftests so this is respond for this
> > > request.
> > 
> > gem_cs_prefetch itself does one thing: verify that we cannot cross the
> > page boundary beyond the last page of the GTT. It is about the Command
> > Streamer prefetch; there is no command streamer here.
> > 
> > gem_cs_prefetch could be simplified by EXEC_OBJECT_PINNED, I think the
> > notes got muddled up.
> > -Chris
> Probably you are right. I focused on some other point of view. My test is 
> checking
> that if we cross the boundary beyond the last page values are stored in 
> scratch.

If we cross the boundary beyond the end of the last page of the GTT, there are 
more pages. Hitting scratch is not a sensible test; scratch is just a
figment of the imagination, the only reason it may exist in some
circumstances is to prevent page faults. And other than vtd w/a that
was a bad idea.
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