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Why Qt platform plugin “xcb” cannot be loaded even though it was found?
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Here's the whole output with QT_DEBUG_PLUGINS=1:
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5pi/plugins/platforms" ... QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqeglfs.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqeglfs.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "eglfs" ] }, "archreq": 0, "className": "QEglFSIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("eglfs") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqlinuxfb.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqlinuxfb.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "linuxfb" ] }, "archreq": 0, "className": "QLinuxFbIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("linuxfb") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqminimal.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqminimal.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "minimal" ] }, "archreq": 0, "className": "QMinimalIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("minimal") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqminimalegl.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqminimalegl.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "minimalegl" ] }, "archreq": 0, "className": "QMinimalEglIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("minimalegl") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqoffscreen.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqoffscreen.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "offscreen" ] }, "archreq": 0, "className": "QOffscreenIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("offscreen") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqvnc.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqvnc.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "vnc" ] }, "archreq": 0, "className": "QVncIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("vnc") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqwebgl.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqwebgl.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "webgl" ] }, "archreq": 0, "className": "QWebGLIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("webgl") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqxcb.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqxcb.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "xcb" ] }, "archreq": 0, "className": "QXcbIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("xcb") QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5pi/plugins" ... QFactoryLoader::QFactoryLoader() checking directory path "/home/user/app-directory" ... QFactoryLoader::QFactoryLoader() looking at "/home/user/app-directory/app" "Failed to extract plugin meta data from '/home/user/app-directory/app'" not a plugin QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5pi/plugins/platforms/platforms" ... QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5pi/plugins/platforms" ... QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqeglfs.so" Got keys from plugin meta data ("eglfs") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqlinuxfb.so" Got keys from plugin meta data ("linuxfb") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqminimal.so" Got keys from plugin meta data ("minimal") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqminimalegl.so" Got keys from plugin meta data ("minimalegl") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqoffscreen.so" Got keys from plugin meta data ("offscreen") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqvnc.so" Got keys from plugin meta data ("vnc") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqwebgl.so" Got keys from plugin meta data ("webgl") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqxcb.so" Got keys from plugin meta data ("xcb") QFactoryLoader::QFactoryLoader() checking directory path "/home/user/app-directory/platforms" ... Could not load shared library symbols for /usr/local/qt5pi/plugins/platforms/libqxcb.so. Do you need "set solib-search-path" or "set sysroot"?loaded library "/usr/local/qt5pi/plugins/platforms/libqxcb.so" qt.qpa.xcb: could not connect to display qt.qpa.xcb: could not connect to display qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/usr/local/qt5pi/plugins/platforms" even though it was found. This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem. Available platform plugins are: eglfs (from /usr/local/qt5pi/plugins/platforms), linuxfb (from /usr/local/qt5pi/plugins/platforms), minimal (from /usr/local/qt5pi/plugins/platforms), minimalegl (from /usr/local/qt5pi/plugins/platforms), offscreen (from /usr/local/qt5pi/plugins/platforms), vnc (from /usr/local/qt5pi/plugins/platforms), webgl (from /usr/local/qt5pi/plugins/platforms), xcb (from /usr/local/qt5pi/plugins/platforms), eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, webgl, xcb.TL;DR:
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqxcb.so" Found metadata in lib /usr/local/qt5pi/plugins/platforms/libqxcb.so, metadata= { "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3", "MetaData": { "Keys": [ "xcb" ] }, "archreq": 0, "className": "QXcbIntegrationPlugin", "debug": false, "version": 330752 } Got keys from plugin meta data ("xcb") QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5pi/plugins" ... QFactoryLoader::QFactoryLoader() checking directory path "/home/user/app-directory" ... QFactoryLoader::QFactoryLoader() looking at "/home/user/app-directory/app" "Failed to extract plugin meta data from '/home/user/app-directory/app'" not a plugin QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5pi/plugins/platforms/platforms" ... QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5pi/plugins/platforms" ... QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqeglfs.so" Got keys from plugin meta data ("eglfs") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqlinuxfb.so" Got keys from plugin meta data ("linuxfb") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqminimal.so" Got keys from plugin meta data ("minimal") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqminimalegl.so" Got keys from plugin meta data ("minimalegl") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqoffscreen.so" Got keys from plugin meta data ("offscreen") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqvnc.so" Got keys from plugin meta data ("vnc") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqwebgl.so" Got keys from plugin meta data ("webgl") QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5pi/plugins/platforms/libqxcb.so" Got keys from plugin meta data ("xcb") QFactoryLoader::QFactoryLoader() checking directory path "/home/user/app-directory/platforms" ... Could not load shared library symbols for /usr/local/qt5pi/plugins/platforms/libqxcb.so. Do you need "set solib-search-path" or "set sysroot"?loaded library "/usr/local/qt5pi/plugins/platforms/libqxcb.so" qt.qpa.xcb: could not connect to display qt.qpa.xcb: could not connect to display qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/usr/local/qt5pi/plugins/platforms" even though it was found. This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem. Available platform plugins are: eglfs (from /usr/local/qt5pi/plugins/platforms), linuxfb (from /usr/local/qt5pi/plugins/platforms), minimal (from /usr/local/qt5pi/plugins/platforms), minimalegl (from /usr/local/qt5pi/plugins/platforms), offscreen (from /usr/local/qt5pi/plugins/platforms), vnc (from /usr/local/qt5pi/plugins/platforms), webgl (from /usr/local/qt5pi/plugins/platforms), xcb (from /usr/local/qt5pi/plugins/platforms), eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, webgl, xcb.@rrd0 from your error log please see entries like this
qt.qpa.xcb: could not connect to display
that coupled with the way you said you're starting your app
when I try to run the same app from a remote debug session
seems to me that you're not using a SSH session with X Forwarding... don't forget the -X parameter along with proper hosts authorization
ssh -X user@hostname -
@rrd0 from your error log please see entries like this
qt.qpa.xcb: could not connect to display
that coupled with the way you said you're starting your app
when I try to run the same app from a remote debug session
seems to me that you're not using a SSH session with X Forwarding... don't forget the -X parameter along with proper hosts authorization
ssh -X user@hostnameI'm not using X forwarding. The app is displayed on the target. Just text (stdout and stderr, I guess) is displayed on my dev machine.
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You still have to configure things properly. You are starting your application remotely, so you have to configure your session so that your application tries to connect to the local X server.
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You still have to configure things properly. You are starting your application remotely, so you have to configure your session so that your application tries to connect to the local X server.
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I may be wrong but I don't think you currently can.
Out of curiosity, what is the reason for having a full X server running on your embedded target ?
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I may be wrong but I don't think you currently can.
Out of curiosity, what is the reason for having a full X server running on your embedded target ?
I'm using X cause I tried (a lot) to run my apps on EGLFS with no success. I followed the RaspberryPi2EGLFS guide, from qt wiki, to build Qt for RPi, but never managed to make it work.
Do you know some other guide that could help me build Qt (EGLFS) for RPi?
P.S. Someone updated the RaspberryPi2EGLFS guide, so I'll give it a last try.
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Hi, I also run Qt apps on my Raspberry Pi, and when I had problems using the
-platform xcbto connect to them, I instead use-platform vncworks fine.
(On my PC I use vncviewer.exe to connect)I'll try that. Thanks!
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Any chance you are having trouble using a Raspbian Stretch root filesystem ?
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The EGLFS issue.
