[Intel-gfx] [PATCH v2] drm/i915: Exclude low pages (128KiB) of stolen from use

[Chris Wilson]

Quoting Ville Syrjälä (2020-10-08 11:04:22)
> On Thu, Oct 08, 2020 at 10:54:36AM +0100, Chris Wilson wrote:
> > The GPU is trashing the low pages of its reserved memory upon reset. If
> > we are using this memory for ringbuffers, then we will dutiful resubmit
> > the trashed rings after the reset causing further resets, and worse. We
> > must exclude this range from our own use. The value of 128KiB was found
> > by empirical measurement on gen9.
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: stable at vger.kernel.org
> > ---
> > v2 comes with a selftest to see how widespread the issue is
> 
> Do we need something to make sure FBC isn't scribbling into
> stolen during the test?

igt runs the tests with disable_display=1, that is still being honoured
right?

I did think about looking up the address to see if the drm_mm_node is in
use to try and filter out such users. For starters, I just want to
confirm that CI is seeing what I'm seeing.
-Chris