[Intel-gfx] [PATCH v4] drm/i915/gt: Poison GTT scratch pages

[Matthew Auld]

On Fri, 24 Jan 2020 at 11:51, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> Using a clear page for scratch means that we have relatively benign
> errors in case it is accidentally used, but that can be rather too
> benign for debugging. If we poison the scratch, ideally it quickly
> results in an obvious error.
>
> v2: Set each page individually just in case we are using highmem for our
> scratch page.
> v3: Pick a new scratch register as MI_STORE_REGISTER_MEM does not work
> with GPR0 on gen7, unbelievably.
> v4: Haswell still considers 3DPRIM a privileged register!
>
> Suggested-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> Cc: Matthew Auld <matthew.william.auld at gmail.com>
Reviewed-by: Matthew Auld <matthew.william.auld at gmail.com>