Ubuntu 20.04, XServer and Qt applicatons with QOpenGLWidget

AntonBogomolov

Hello!

Hardware: ITX-3588J and two monitors

Software:
Ubuntu 20.04.4 LTS (GNU/Linux 5.10.66 aarch64)
Qt version 5.12.8 installed on ITX-3588J by: sudo apt-get install build-essential qt5-default
X.Org X Server 1.20.8

When we trying to run a qt application with QOpenGLWidget on two monitors (the window has a size 3840x1080), there were problems.

First scenario (Used eglfs):

1. sudo killall -3 gnome-shell
   
2. export QT_QPA_PLATFORM=eglfs
   
3. export QT_QPA_EGLFS_INTEGRATION=eglfs_kms
   
4. export QT_QPA_EGLFS_KMS_ATOMIC=1
   
5. export QT_QPA_EGLFS_KMS_CONFIG=/home/firefly/kms_config.json
   
6. ./ZeroCopyGLSample

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kms_config.json are:

1. {
   
2.   "device": "/dev/dri/card0",
   
3.   "outputs": [
   
4.     {
   
5.       "name": "HDMI1",
   
6.       "mode": "1920x1080"
   
7.     },
   
8.     {
   
9.       "name": "HDMI2",
   
10.       "mode": "1920x1080"
    
11.     }
    
12.   ]
    
13. }

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Everything starts and works well, except that the application can only use one monitor, although qApp→screens() correctly returns both devices. Attempts to create widgets with the geometry of the second monitor did not give the expected result.

Second scenario (Used Xserver):

xinit /home/firefly/testapps/OpenGL/ZeroCopyGLSample/ZeroCopyGLSample

The application starts, a window is created on two monitors, but OpenGL does not work correctly:

1. QXcbIntegration: Cannot create platform OpenGL context, neither GLX nor EGL are enabled
   
2. QOpenGLWidget: Failed to create context

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I would be grateful for any hint
Thanks for the help!

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