Hi Gerd, > > Why does Qemu need a new Wayland UI backend? > > The main reason why there needs to be a plain and simple Wayland backend > > for Qemu UI is to eliminate the Blit (aka GPU copy) that happens if using > > a toolkit like GTK or SDL (because they use EGL). The Blit can be eliminated > > by sharing the dmabuf fd -- associated with the Guest scanout buffer -- > > directly with the Host compositor via the linux-dmabuf (unstable) protocol. > > Hmm, that probably means no window decorations (and other UI elements), [Kasireddy, Vivek] Right, unfortunately, no decorations or other UI elements. For that we can use GTK. > right? Also the code seems to not (yet?) handle mouse and kbd input. [Kasireddy, Vivek] Yes, kbd and mouse support not added yet and that is why I tagged it as WIP. But it should not be too hard to add that.
> > > The patch(es) are still WIP and the only reason why I am sending them now > > is to get feedback and see if anyone thinks this work is interesting. And, > > even after this work is complete, it is not meant to be merged and can be > > used for performance testing purposes. Given Qemu UI's new direction, the > > proper way to add new backends is to create a separate UI/display module > > that is part of the dbus/pipewire infrastructure that Marc-Andre is > > working on: > > https://lists.nongnu.org/archive/html/qemu-devel/2021-03/msg04331.html > > Separating emulation and UI has the big advantage that the guest > lifecycle is decoupled from the desktop session lifecycle, i.e. > the guest can continue to run when the desktop session ends. > > Works today with spice (when using unix socket to connect it can pass > dma-buf handles from qemu to spice client). > > Using dbus instead certainly makes sense. Whenever we'll just go send > dma-buf handles over dbus or integrate with pipewire for display/sound > not clear yet. Marc-André thinks using pipewire doesn't bring benefits > and I havn't found the time yet to learn more about pipewire ... [Kasireddy, Vivek] On our side, we'll also try to learn how dbus and pipewire fit in and work. Having said that, can Marc-Andre's work be merged in stages -- first only dbus and no pipewire? Thanks, Vivek > > take care, > Gerd
