Bug 102475 - Can't use keyboard arrows in kvm with the keyboard grabbing change
Summary: Can't use keyboard arrows in kvm with the keyboard grabbing change
Alias: None
Product: Wayland
Classification: Unclassified
Component: XWayland (show other bugs)
Version: unspecified
Hardware: Other All
: medium normal
Assignee: Wayland bug list
QA Contact: Xorg Project Team
Depends on:
Reported: 2017-08-30 11:42 UTC by Sebastien Bacher
Modified: 2019-05-10 15:53 UTC (History)
0 users

See Also:
i915 platform:
i915 features:

Test patch (3.22 KB, patch)
2017-08-31 16:26 UTC, Olivier Fourdan
Details | Splinter Review

Description Sebastien Bacher 2017-08-30 11:42:57 UTC
The Ubuntu maintainer backported the recent change to add keyboard grabbing to xwayland, with that change the keyboard arrow keys stop working in kvm
Comment 1 Olivier Fourdan 2017-08-30 12:40:12 UTC
Can you please elaborate of what exactly has been backported and the resulting patches?

Which Wayland compositor do you use?

It's worth noting that the xwayland patches in themselves won't make a difference *unless* the Wayland compositor implements the corresponding protocol, and I am aware of none for now (the patch for mutter is still pending).
Comment 2 Sebastien Bacher 2017-08-30 13:36:16 UTC
The Ubuntu diff is

it looks like the backported commits are 

+d5e2f271ad93e50 xwayland: Remove two unused proc pointers.
+ca17f3e9fd3b59f xwayland: Lock the pointer if it is confined and has no cursor
+513e3bd3870fdb8 xwayland: Update root window size when desktop size changes
+fafdb0cc9697eb5 xwayland: "Accept" confineTo on InputOnly windows
+c217fcb4c4640ff xwayland: Allow pointer warp on root/None window


Ubuntu doesn't have any compositor change, it's standard GNOME 3.24 so there is must be something wrong and it does make a difference without implementing the protocole.

Note that reverting 0a448d133 does fix the issue
Comment 3 Olivier Fourdan 2017-08-30 14:57:34 UTC
Tried reproducing the issue with the arrow keys using the current Xwayland from master with mutter/gnome-shell from master, using qemu-kvm with SDL backend (-display sdl) but failedto reproduce, all keys (including the arrow keys) work fine in the guest.
Comment 4 Olivier Fourdan 2017-08-31 16:26:13 UTC
Created attachment 133910 [details] [review]
Test patch

Can you try the attached patch (this is for testing purpose *only*) and report back if that makes any difference?

With this patch, if the compositor has no support for Xwayland keyboard grab protocol as you said you haven't in Ubuntu, Xwayland won't set up its grab handler at all.
Comment 5 Sebastien Bacher 2017-08-31 23:04:19 UTC
the patch doesn't seem to make a difference
Comment 6 Olivier Fourdan 2017-09-01 07:15:06 UTC
Well, what this patch does is disabling any specific grab handler if the Xwayland grab protocol is not available, by postponing the setup of those handler until Xwayland can bind to the relevant interface as advertised by the compositor.

If the compositor doesn't support the Xwayland grab protocol, then all those routines are not "enabled" in Xwayland, I don't see how they could break anything if not used...

Unfortunately, we cannot tell whether or not the compositor supports the Xwayland grab protocol using something like weston-info because, for security reasons, the compositor will (should) only advertiset he given protocl to Xwayland alone and hide it to any other client.

So, if that patch makes no difference, it means that:

 - The Wayland compositor claim to support Xwayland grab protocol but is buggy and doesn't send all key events as expected

 - Or the problem is completely unrelated to this patch.

So next step for you is to:

 - Check the actual patches applied to mutter in Ubuntu
 - Check what happens at the protocol level

To do so, yo can use the envvar WAYLAND_DEBUG prior to start gnome-shell (which will spawn Xwayland) so that we can tell what globals are listed in the wl_registry and see if "zwp_xwayland_keyboard_grab_manager_v1" is one of them.

e.g., from a console:

  $ WAYLAND_DEBUG=1 dbus-run-session -- gnome-shell --display-server --wayland |& tee ~/wayland-debug.log

The wl_registry globals will be listed at the beginning of the log so that should be enough to tell if the compositor claims to be supporting "zwp_xwayland_keyboard_grab_manager_v1".

Then, you can start qemu-kvm as usual and try to press the keys that do not work, those will be captured in the log as well, so we can tell if the compositor sends those key events to the client (Xwayland, in which case the problem lies in Xwayland) or not (in which case the problem lies in the compositor).

Please attach the "wayland-debug.log" to this bugzilla once you've performed those tests (but make sure you don't type any sensitive data in any application while the log is being captured as any key event will be logged).
Comment 7 Sebastien Bacher 2017-09-01 16:43:07 UTC
the issue isn't there when using your debug command but it begins in that session if gsd-media-keys is started... I'm calling it a week now but I'm going to poke to it a bit more on monday
Comment 8 GitLab Migration User 2019-05-10 15:53:05 UTC
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