[Intel-gfx] Small bar recovery vs compressed content on DG2

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

Hi!

Do we somehow need to clarify in the headers the semantics for this?

 From my understanding when discussing the CCS migration series with 
Ram, the kernel will never do any resolving (compressing / 
decompressing) migrations or evictions which basically implies the 
following:

*) Compressed data must have LMEM only placement, otherwise the GPU 
would read garbage if accessing from SMEM.
*) Compressed data can't be assumed to be mappable by the CPU, because 
in order to ensure that on small BAR, the placement needs to be LMEM+SMEM.
*) Neither can compressed data be part of a CAPTURE buffer, because that 
requires the data to be CPU-mappable.

Are we (and user-mode drivers) OK with these restrictions, or do we need 
to rethink?

Thanks,

Thomas