Hi,
On 3/19/20 4:16 PM, Pekka Paalanen wrote:
On Thu, 19 Mar 2020 15:30:03 +0100 Hans de Goede hdegoede@redhat.com wrote:
<snip>
The only way to fix that is to stop Weston from putting non-cursor content on the cursor plane.
Correct.
Is that something that should be done?
If the hotspot property also had a "disabled" value, then Weston could set the hotspot to disabled when it is using the cursor plane for non-cursor content and not lose the feature. And of course set hotspot correctly when it in fact is a cursor (but for what input?).
I believe cursor planes in the affected virtual gfx-cards do not really have a mode where they can actually be used as a generic overlay plane, certainly not in a useful manner (if anything works it will all be software emulation), implementing a hotspot disabled mode would be tricky and this would needs to be duplicated in all virtual-gfx cards kms drivers.
If I understood Daniel's proposal for how to deal with this properly, then only cursor planes which actually need them would get the new hotspot x/y properties. If we do that then Weston could use the presence of the hotspot x/y properties to detect if it is dealing with a proper hw plane which can also be used as a generic plane; or a virtual-gfx cards cursor-plane, and then just not bother with trying to use the plane as a generic hw plane.
Would that work?
<snip>
I think one of the major reasons why Wayland pointer relative motion and confinement extensions were designed was VM- etc. viewers, and of course games.
ack.
What if display servers stop using the cursor plane completely, because people may hit a case where a VM-viewer makes the wrong assumption about which input device is associated to which cursor plane inside the VM?
The confine + warp trick is typically the default mode and only if the guest indicates through e.g. a guest-agent process that seamless mode is supported then seamless mode is enabled.
IOW the VM is careful to not enable it when it might not work.
How would the guest-agent know? Does it check that there is literally only one pointer input device and that comes from the VM-viewer? Or does it limit seamless to white-listed display servers perhaps?
This varies between different solutions. E.g. the spice vdagent has a desktop component which is started with a /etc/xdg/autostart/foo.desktop file, assuming that it will work with any desktops honoring /etc/xdg/autostart.
VirtualBox OTOH assumes it can use seamless mode as soon as the vboxvideo driver loads inside the guest.
Regards,
Hans