[Mesa-dev] [PATCH 1/2] gallium: Add PIPE_CAP_USER_MEMORY_PAGE_SIZE for page size of user pointers

[Alex Deucher]

On Wed, Aug 16, 2017 at 11:34 PM, Michel Dänzer <michel at daenzer.net> wrote:
> On 17/08/17 12:33 PM, Aaron Watry wrote:
>> On Wed, Aug 16, 2017 at 9:48 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
>>> On Wed, Aug 16, 2017 at 10:39 PM, Michel Dänzer <michel at daenzer.net> wrote:
>>>> On 17/08/17 10:52 AM, Aaron Watry wrote:
>>>>> PIPE_CAP_RESOURCE_FROM_USER_MEMORY says that size must be page aligned,
>>>>> but doesn't necessarily say anything about the size of those pages.
>>>>
>>>> Is there any case known so far where it's not the CPU page size?
>>>
>>> It's always the CPU page size.  The limitation is not a hw limitation,
>>> it's a sw limitation with the way the kernel handles creating BOs from
>>> user memory.
>>
>> So this won't change with the 2MB pages that are coming up for Vega?
>
> I don't think it will, that's only about VRAM.

It applies to system memory as well, e.g., transparent huge pages, or
larger page sizes in general.  I don't think that affects this
however.

Alex

>
>
>> If so, I guess I can just use getpagesize() in patch 2 for now and skip the CAP.
>
> Right.
>
>
> --
> Earthling Michel Dänzer               |               http://www.amd.com
> Libre software enthusiast             |             Mesa and X developer