vblank-synchronized Present copy

[Matthieu Herrb]

On Thu, Nov 24, 2022 at 12:05:12PM +0800, Po Lu wrote:
> Here is a change to xf86-video-modesetting that should let PresentPixmap
> copy within the vertical blanking period, as opposed to immediately
> after.  I'm not sure whether or not it's ok to depend on timerfd, and to
> also send the PresentCompleteNotify event at vblank start time (as
> opposed to the first-pixel-out time, which is when it's sent in response
> to a page flip.)
> 

Not all systems supported by X.Org have timerfd. So please make this
feàture conditional it's presence,

-- 
Matthieu Herrb