[Mesa-dev] Linux Graphics Next: Userspace submission update

Daniel Vetter daniel at ffwll.ch
Wed Jun 2 19:20:28 UTC 2021

On Wed, Jun 02, 2021 at 10:09:01AM +0200, Michel Dänzer wrote:
> On 2021-06-01 12:49 p.m., Michel Dänzer wrote:
> > On 2021-06-01 12:21 p.m., Christian König wrote:
> > 
> >> Another question is if that is sufficient as security for the display server or if we need further handling down the road? I mean essentially we are moving the reliability problem into the display server.
> > 
> > Good question. This should generally protect the display server from freezing due to client fences never signalling, but there might still be corner cases.
> E.g. a client might be able to sneak in a fence between when the
> compositor checks fences and when it submits its drawing to the kernel.

This is why implicit sync should be handled with explicit IPC. You pick
the fence up once, and then you need to tell your GL stack to _not_ do
implicit sync. Would need a new extension. vk afaiui does this
automatically already.
Daniel Vetter
Software Engineer, Intel Corporation

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