[Mesa-dev] [PATCH] anv: Stop setting domains to RENDER on EXEC_OBJECT_WRITE

[Matt Turner]

On Sat, Jul 8, 2017 at 11:05 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> On July 7, 2017 1:52:54 PM Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
>> Quoting Jason Ekstrand (2017-07-07 21:37:29)
>>>
>>> The reason we were doing this was to ensure that the kernel did the
>>> appropriate cross-ring synchronization and flushing.  However, the
>>> kernel only looks at EXEC_OBJECT_WRITE to determine whether or not to
>>> insert a fence.  It only cares about the domain for determining whether
>>> or not it needs to clflush the BO before using it for scanout but the
>>> domain automatically gets set to RENDER internally by the kernel if
>>> EXEC_OBJECT_WRITE is set.
>>
>>
>> Once upon a time we also depended upon EXEC_OBJECT_WRITE for correct
>> swapout. That was until I saw what you were planning to do for anv. Hmm,
>> that puts the oldest kernel that might support anv as
>>
>> commit 51bc140431e233284660b1d22c47dec9ecdb521e [v4.3]
>> Author: Chris Wilson <chris at chris-wilson.co.uk>
>> Date:   Mon Aug 31 15:10:39 2015 +0100
>>
>>     drm/i915: Always mark the object as dirty when used by the GPU
>
>
> I think we're probably ok there.  We have a hard requirement on memfd which
> I think landed in 4.6 though I could be wrong about that.

No. memfd_create was added in 3.17.