[RFC PATCH 098/162] drm/i915/gtt: map the PD up front

[Chris Wilson]

Quoting Matthew Auld (2020-11-27 12:06:14)
> We need to general our accessor for the page directories and tables from
> using the simple kmap_atomic to support local memory, and this setup
> must be done on acquisition of the backing storage prior to entering
> fence execution contexts. Here we replace the kmap with the object
> maping code that for simple single page shmemfs object will return a
> plain kmap, that is then kept for the lifetime of the page directory.
> 
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

We are going to really struggle with this on 32b :(
-Chris