On Tue, 2021-01-05 at 12:30 +0100, Thomas Zimmermann wrote: > Hi > > Am 05.01.21 um 12:04 schrieb Gerd Hoffmann: > > Hi, > > > > > > It's not possible to do page flip with this virtual device. The > > > > call to > > > > SYNTHVID_VRAM_LOCATION is only honoured once. So unfortunately > > > > need to > > > > use SHMEM helpers. > > > > > > I was thinking about using struct > > > video_output_situation.vram_offset; in > > > case you want to tinker with that. There's a comment in the patch > > > that > > > vram_offset should always be 0. But this comment seems incorrect > > > for devices > > > with more than one output. > > > > Where does the comment come from? fbdev drivers support a single > > framebuffer only so for a fbdev driver it makes sense to set the > > offset > > to 0 unconditionally. With drm you probably can handle things > > differently ... > > I cannot find it in hyperv_fb.c; it must have gotten introduced here. > > Only one display is supported by this DRM driver, so the comment is > correct. In the future, having support for multiple displays might be > an > option. > > Beside that offset should be 0, another problem is that SYNTHVID_SITUATION_UPDATE will cause the whole screen to flicker (I suppose this call is more for changing resolution), so can't really use this for page-flip.
