[Intel-gfx] [RFC 53/60] drm/i915: Create stolen memory region from local memory

[Matthew Auld]

On 13/07/2020 05:48, Dave Airlie wrote:
> On Fri, 10 Jul 2020 at 22:01, Matthew Auld <matthew.auld at intel.com> wrote:
>>
>> From: CQ Tang <cq.tang at intel.com>
>>
>> Add "REGION_STOLEN" device info to dg1, create stolen memory
>> region from upper portion of local device memory, starting
>> from DSMBASE.
>>
>> The memory region is marked with "is_devmem=true".
> 
> So is stolen fake on LMEM devices? The concept of stolen doesn't seem
> to make much sense with VRAM, so please enlighten me.

CQ, do we actually need an explicit stolen LMEM region? The idea of 
having a DSM like stolen region for LMEM does sound strange(outside of 
the usual reserved portions which are for HW use etc), since the driver 
has complete control over LMEM. Is it just a convenience thing to keep 
things working as-is for fbc, initial fb, etc. or is there more to it? 
There is buddy_alloc_range() for LMEM which we could potentially use to 
wrap an object around for things like the initial fb or similar.

> 
> Dave.
>