https://bugzilla.kernel.org/show_bug.cgi?id=196777 --- Comment #12 from Justin M. Forbes (jmforbes@xxxxxxxxxxx) --- (In reply to Gerd Hoffmann from comment #11) > (In reply to Justin M. Forbes from comment #10) > > After going through these with a number of users: > > > > qxl: fix primary surface handling - This patch is widely reported to cause > > serious screen flickering that is not there without it, making the system > > unusable. > > Workaround #1: turn off wayland. Possible as a short term fix, but with wayland being pretty much "the way forward" it doesn't seem to be a workable long term solution. > Workaround #2: use virtio-vga instead. wayland doesn't use qxl 2d accel > anyway. > > Fundamental problem here is that the qxl virtual hardware simply doesn't > support pageflip, we have to destroy + re-create the primary surface > instead. This is where the flicker comes from. > > Commit "058e9f5c82 drm/qxl: simple crtc page flipping emulated using buffer > copy" handles the issue with a pretty gross hack, blitting one framebuffer > over the other instead of a proper primary surface update. With atomic > modesetting that doesn't work any more. > > We could possibly decouple the primary surface from the drm framebuffers, so > the drm framebuffers effectively become shadow framebuffers, and every > display update becomes a drm framebuffer -> primary surface blit. Not sure > whenever that scheme can work properly with xorg though. Also has a high > chance to cause xorg performance regressions. > So this brings up an interesting problem in how things are to move forward. It came up as a blocker in Fedora 27 today. Let's say we find a way to force boxes to revert to virtio-vga. That wouldn't change any existing VMs, and it is something we have no control over when the host is not Fedora as well. It also would be a problem for non wayland guests. -- You are receiving this mail because: You are watching the assignee of the bug. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
