On 2019.05.27 14:22:37 +0200, Gerd Hoffmann wrote: > On Mon, May 27, 2019 at 05:07:41PM +0800, Zhenyu Wang wrote: > > On 2019.05.27 16:43:11 +0800, Tina Zhang wrote: > > > Add VFIO_DEVICE_SET_GFX_FLIP_EVENTFD ioctl command to set eventfd > > > based signaling mechanism to deliver vGPU framebuffer page flip > > > event to userspace. > > > > Should we add probe to see if driver can support gfx flip event? > > Userspace can simply call VFIO_DEVICE_SET_GFX_FLIP_EVENTFD and see if it > worked. If so -> use the eventfd. Otherwise take the fallback path > (timer based polling). I can't see any advantage a separate feature > probe steps adds. > Then we need to define error return which means driver doesn't support e.g -ENOTTY, and driver shouldn't return that for other possible failure, so user space won't get confused. I think if we can define this as generic display event notification? Not necessarily just for flip, just a display change notification to let user space query current state. -- Open Source Technology Center, Intel ltd. $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827
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