qt.qpa.plugin: Could not load the Qt platform plugin "wayland-egl" in "" even though it was found.

[M4Z4]

Seems, that the Qt application doesn't start after adding the "--modules=screen.share.so" to services.

Any tips how to debug/fix the problem?

HW/SW

iMX8

ID=poky
NAME="Poky (Yocto Project Reference Distro)"
VERSION="3.3 (hardknott)"
VERSION_ID=3.3
PRETTY_NAME="Poky (Yocto Project Reference Distro) 3.3 (hardknott)"
root@sm2s-imx8mp:/etc/systemd/system#

Basic overview:

Trying to create RDP connection to a Qt GUI-application.

Running “first” weston with…
drm-backend
screen-share
Qt-application (CPX Control Panel is the Qt application)

…and RDP command is executed from weston.ini*, when the “second” Weston is started

• rdp-backend
• fullscreen-shell

*=weston.ini

[screen-share]
command=@bindir@/weston --backend=rdp-backend.so --rdp-tls-cert=/data/etc/ssh/tls.crt --rdp-tls-key=/data/etc/ssh/tls.key --shell=fullscreen-shell.so --no-clients-resize --no-config
start-on-startup=true

CPX service

############

Wayland

############
export QT_QPA_PLATFORM=wayland-egl
export WAYLAND_DISPLAY=wayland-0

if test -z "$XDG_RUNTIME_DIR"; then
export XDG_RUNTIME_DIR=/run/user/id -u
fi

Weston plugins

[Service]

Requires systemd-notify.so Weston plugin.

Type=notify
EnvironmentFile=/etc/default/weston
ExecStart=/usr/bin/weston --log=${XDG_RUNTIME_DIR}/weston.log --modules=systemd-notify.so --modules=screen.share.so

root@sm2s-imx8mp:~# journalctl -u cpx.service
-- Journal begins at Fri 2023-01-13 08:19:03 CET, ends at Fri 2023-01-13 10:26:26 CET. --
Jan 13 08:20:06 sm2s-imx8mp systemd[1]: Started CPX Control Panel.
Jan 13 08:20:06 sm2s-imx8mp cpx.sh[769]: qt.core.logging: Loading "logging.ini" ...
Jan 13 08:20:06 sm2s-imx8mp cpx.sh[769]: Failed to create wl_display (No such file or directory)
Jan 13 08:20:06 sm2s-imx8mp cpx.sh[769]: EGL: Warning: No default display support on wayland
Jan 13 08:20:06 sm2s-imx8mp cpx.sh[769]: qt.qpa.wayland: EGL not available
Jan 13 08:20:06 sm2s-imx8mp cpx.sh[769]: qt.qpa.plugin: Could not load the Qt platform plugin "wayland-egl" in "" even though it was found.
Jan 13 08:20:06 sm2s-imx8mp cpx.sh[769]: This application failed to start because no Qt platform plugin could be initialized. Reinstalling the app>
Jan 13 08:20:06 sm2s-imx8mp cpx.sh[769]: Available platform plugins are: wayland, offscreen, vnc, minimal, minimalegl, vkkhrdisplay, eglfs, waylan>
Jan 13 08:20:06 sm2s-imx8mp cpx.sh[764]: /opt/cpx/cpx.sh: line 84:   769 Aborted                 ./cpx --display=LVDS-1 --rotate=0 "$@"
Jan 13 08:20:06 sm2s-imx8mp systemd[1]: cpx.service: Main process exited, code=exited, status=134/n/a
Jan 13 08:20:06 sm2s-imx8mp systemd[1]: cpx.service: Failed with result 'exit-code'.

I’ve also run the Qt with DEBUG option(QT_DEBUG_PLUGINS=1) and here is the log:

Jan 13 11:55:32 sm2s-imx8mp systemd[1]: Started CPX Control Panel.
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.logging: Loading "logging.ini" ...
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: checking directory path "/usr/lib/plugins/platforms" ...
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: looking at "/usr/lib/plugins/platforms/libqwayland-generic.so"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.loader: Found metadata in lib /usr/lib/plugins/platforms/libqwayland-generic.so, metadata=
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "MetaData": {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         "Keys": [
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:             "wayland"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         ]
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     },
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "archlevel": 0,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "className": "QWaylandIntegrationPlugin",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "debug": false,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "version": 394240
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: }
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wayland")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: looking at "/usr/lib/plugins/platforms/libqoffscreen.so"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.loader: Found metadata in lib /usr/lib/plugins/platforms/libqoffscreen.so, metadata=
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "MetaData": {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         "Keys": [
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:             "offscreen"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         ]
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     },
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "archlevel": 0,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "className": "QOffscreenIntegrationPlugin",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "debug": false,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "version": 394240
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: }
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("offscreen")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: looking at "/usr/lib/plugins/platforms/libqvnc.so"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.loader: Found metadata in lib /usr/lib/plugins/platforms/libqvnc.so, metadata=
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "MetaData": {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         "Keys": [
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:             "vnc"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         ]
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     },
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "archlevel": 0,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "className": "QVncIntegrationPlugin",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "debug": false,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "version": 394240
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: }
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("vnc")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: looking at "/usr/lib/plugins/platforms/libqminimal.so"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.loader: Found metadata in lib /usr/lib/plugins/platforms/libqminimal.so, metadata=
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "MetaData": {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         "Keys": [
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:             "minimal"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         ]
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     },
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "archlevel": 0,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "className": "QMinimalIntegrationPlugin",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "debug": false,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "version": 394240
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: }
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("minimal")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: looking at "/usr/lib/plugins/platforms/libqminimalegl.so"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.loader: Found metadata in lib /usr/lib/plugins/platforms/libqminimalegl.so, metadata=
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "MetaData": {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         "Keys": [
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:             "minimalegl"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         ]
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     },
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "archlevel": 0,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "className": "QMinimalEglIntegrationPlugin",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "debug": false,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "version": 394240
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: }
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("minimalegl")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: looking at "/usr/lib/plugins/platforms/libqvkkhrdisplay.so"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.loader: Found metadata in lib /usr/lib/plugins/platforms/libqvkkhrdisplay.so, metadata=
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "MetaData": {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         "Keys": [
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:             "vkkhrdisplay"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         ]
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     },
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "archlevel": 0,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "className": "QVkKhrDisplayIntegrationPlugin",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "debug": false,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "version": 394240
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: }
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("vkkhrdisplay")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: looking at "/usr/lib/plugins/platforms/libqeglfs.so"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.loader: Found metadata in lib /usr/lib/plugins/platforms/libqeglfs.so, metadata=
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "MetaData": {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         "Keys": [
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:             "eglfs"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         ]
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     },
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "archlevel": 0,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "className": "QEglFSIntegrationPlugin",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "debug": false,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "version": 394240
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: }
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("eglfs")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: looking at "/usr/lib/plugins/platforms/libqwayland-egl.so"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.loader: Found metadata in lib /usr/lib/plugins/platforms/libqwayland-egl.so, metadata=
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "MetaData": {
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         "Keys": [
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:             "wayland-egl"
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:         ]
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     },
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "archlevel": 0,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "className": "QWaylandEglPlatformIntegrationPlugin",
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "debug": false,
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]:     "version": 394240
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: }
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wayland-egl")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: checking directory path "/opt/cpx/platforms" ...
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.library: "/usr/lib/plugins/platforms/libqwayland-egl.so" loaded library
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: Failed to create wl_display (Connection refused)
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: EGL: Warning: No default display support on wayland
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.qpa.wayland: EGL not available
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.qpa.plugin: Could not load the Qt platform plugin "wayland-egl" in "" even though it was found.
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: Available platform plugins are: wayland, offscreen, vnc, minimal, minimalegl, vkkhrdisplay, eglfs, wayland-egl.
Jan 13 11:55:32 sm2s-imx8mp audit[1628]: ANOM_ABEND auid=4294967295 uid=0 gid=0 ses=4294967295 pid=1628 comm="cpx" exe="/opt/cpx/cpx" sig=6 res=1
Jan 13 11:55:32 sm2s-imx8mp kernel: audit: type=1701 audit(1673607332.178:39): auid=4294967295 uid=0 gid=0 ses=4294967295 pid=1628 comm="cpx" exe="/opt/cpx/cpx" sig=6 res=1
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1624]: /opt/cpx/cpx.sh: line 84:  1628 Aborted                 ./cpx --display=LVDS-1 --rotate=0 "$@"
Jan 13 11:55:32 sm2s-imx8mp systemd[1]: cpx.service: Main process exited, code=exited, status=134/n/a
Jan 13 11:55:32 sm2s-imx8mp systemd[1]: cpx.service: Failed with result 'exit-code'.

[sh1981]

When configure Qt, did you add the following arguments?
It seems that the package won't be built unless you explicitly use them.
-eglfs -qpa wayland-egl -qpa xcb

[nbaldy]

@M4Z4
Hi, I'm not 100% sure I follow your launching process, but the error you're getting looks a lot like you are not setting the wayland display export in the same terminal as you run the QT application.

Specifically, this part of the error message:

Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wayland-egl")
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.plugin.factoryloader: checking directory path "/opt/cpx/platforms" ...
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.core.library: "/usr/lib/plugins/platforms/libqwayland-egl.so" loaded library
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: Failed to create wl_display (Connection refused)
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: EGL: Warning: No default display support on wayland
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.qpa.wayland: EGL not available
Jan 13 11:55:32 sm2s-imx8mp cpx.sh[1628]: qt.qpa.plugin: Could not load the Qt platform plugin "wayland-egl" in "" even though it was found.

The connection to the display screen is refused. It looks like either 1) Your path to the wayland display is wrong (check ls -l ${XDG_RUNTIME_DIR}/${WAYLAND_DISPLAY} before running your QT application) or 2) the user running QT does not have permissions. You should be able to see test applications like weston-flower work as well