[Intel-gfx] [PATCH] drm/i915: Exclude top-page for ppgtt as well as ggtt

[Michel Thierry]

On 12/05/17 12:06, Chris Wilson wrote:
> On Fri, May 12, 2017 at 06:55:35PM +0100, Chris Wilson wrote:
>> On Fri, May 12, 2017 at 06:49:09PM +0100, Chris Wilson wrote:
>>> We have always excluded the top-page of the Global GTT to prevent
>>> prefetching past the end of the address space. We have been lax about
>>> applying this restriction to the per-process GTT, but there is no reason
>>> to believe that the hw restriction is any less severe.
>>
>> Other than empirical, but the note in bspec is still there and who knows
>> they may start to be strict again in future.
>
> Fwiw, it looks like we can sleep on this again. Jason no longer believes
> this to be an immediate issue.
> -Chris
>

It might be true for 32b ppgtt, but anything slightly recent should 
already be using 48b.

-Michel