Bug 508526 - Plasma cannot start nested under weston with vnc backend
Summary: Plasma cannot start nested under weston with vnc backend
Status: RESOLVED INTENTIONAL
Alias: None
Product: kwin
Classification: Plasma
Component: platform-wayland-nested (other bugs)
Version First Reported In: 6.4.0
Platform: Gentoo Packages Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-08-20 17:10 UTC by Robin Bankhead
Modified: 2025-09-10 12:10 UTC (History)
4 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:


Attachments
Console output capture (30.01 KB, text/x-log)
2025-08-20 17:10 UTC, Robin Bankhead
Details
Screenshot of Fedora KDE running through Weston via WayPipe remotely and displaying on Mutter (903.05 KB, image/png)
2025-09-10 12:10 UTC, Neal Gompa
Details

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Description Robin Bankhead 2025-08-20 17:10:12 UTC
Created attachment 184290 [details]
Console output capture

SUMMARY
When launched nested under the weston compositor using its vnc backend, startplasma-wayland fails to start a plasma-wayland session and exits immediately. When the weston configuration is changed only to switch the backend to 'drm', plasma-wayland is launched and runs successfully.

The weston.ini configuration is as follows:
[core]
shell=kiosk
backend=vnc
xwayland=false
idle-time=0

[autolaunch]
path=/usr/bin/startplasma-wayland
watch=true

[vnc]
tls-key=/home/robin/weston-vnc/tls.key
tls-cert=/home/robin/weston-vnc/tls.crt

[output]
name=vnc
mode=1366x768
resizeable=true

STEPS TO REPRODUCE
1. From a TTY, launch weston with the above configuration file.

$ export QT_LOGGING_RULES="*.debug=true"
$ dbus-run-session weston -c /path/to/weston.ini &> weston-plasma-vnc.log

OBSERVED RESULT
startplasma-wayland and weston exit after <1s

EXPECTED RESULT
A plasma-wayland session is started nested in weston.


SOFTWARE/OS VERSIONS
KDE Plasma Version: 6.4.4
KDE Frameworks Version: 6.16.0
Qt Version: 6.9.1

Tested both with the current release version of weston (14.0.2) and current git master as packaged by Gentoo. Other compositors such as labwc can be started nested under weston without issues.
Comment 1 David Edmundson 2025-08-28 12:05:41 UTC
startplasma cannot run nested.
Comment 2 Robin Bankhead 2025-08-28 12:17:12 UTC
(In reply to David Edmundson from comment #1)
> startplasma cannot run nested.

It can and does with backend=drm and with every wlroots compositor I have tried (cage, sway, labwc).

If what you mean is "doesn't support it", fair enough, but then I'm unclear why kwin itself does (or so it appears by the existence of this subcategory).
Comment 3 Neal Gompa 2025-09-10 12:10:11 UTC
Created attachment 184862 [details]
Screenshot of Fedora KDE running through Weston via WayPipe remotely and displaying on Mutter

It definitely can run nested, but KWin needs the ability to attach to a drm device for things to work.

The screenshot attached was produced with this launcher script: https://github.com/Internethamster/fedora-cloud-images-kiwi/blob/main/root/usr/local/bin/weston-start-kde-plasma

But you can't have an existing Plasma running in the user, nor can you have the drm device locked by something else.