[Intel-gfx] DG1 VRAM question

[Daniele Ceraolo Spurio]

On 6/26/20 12:14 AM, Lucas De Marchi wrote:
> Cc Matt and Daniele
> 
> On Thu, Jun 25, 2020 at 9:38 PM Dave Airlie <airlied at gmail.com> wrote:
>>
>> I can't figure this out easily so I'd thought I'd just ask, but does
>> DG1 have VRAM > PCIE aperture, I'm not sure I've see any mention of
> 
> We'd need to go via lmem since there's no mappable aperture. There are
> a few patches in tree for that
> (see e.g. 54b512cd7a6d ("drm/i915: do not map aperture if it is not
> available.")) but more missing.
> 

To clarify, although the legacy aperture mapping that allowed the CPU to 
access memory via the GGTT for swizzling is gone, VRAM/LMEM is still 
cpu-mappable via pci bar.
Will leave the questions about possible trashing to Matt as he's more 
familiar than me with how this works.

Daniele

> Lucas De Marchi
> 
>> mappable VRAM vs non-mappable in patches, is it planned to just thrash
>> the aperture if userspace ever ties to map too much of it.
>>
>> Are pagetables stored in the visible RAM space?
>>
>> Dave.
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> 
> 
>