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

[Chris Wilson]

Quoting Chris Wilson (2020-10-07 16:17:18)
> 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.

Probably should double it to 256K, just to be on the safe side?
-Chris