Framebuffer with EGLFS : QXcbConnection: Could not connect to display :0.0

Technical Support
1

Target: Colibri-imx6

I want to compare running QT5 applications with X11 and Framebuffer-EGLFS

This is my procedure, following Openembedded (Core):

  1. Create a LXDE image with Qt5 (X11): bitbake -k angstron-lxde-image
  2. Create a SD card with the LXDE image
  3. Configure QT Creator
  4. Cross Compile and execute (successfully) a QT5 basic “./helloword” application
  5. Modify local.conf for EGLFS and create other image : bitbake -k console-trdx-image
  6. Create a SD card with theconsole-trdx-image
  7. Copy the “./helloworld” application to the new console-trdx-image linux image
  8. When I execute “./helloword” application I get this error: QXcbConnection: Could not connect to display :0.0

*root@colibri-imx6-egfls:~# ./helloworld

QXcbConnection: Could not connect to display :0.0

Aborted

root@colibri-imx6-egfls:~#*

What is wrong?

2

Yes I did follow this article

My helloword is basic QT Widget application.

Executing with --platform eglfs return this error:

root@colibri-imx6-egfls:~# ./helloworld3 --platform eglfs

This application failed to start because it could not find or load the Qt platform plugin “eglfs”.

Available platform plugins are: minimal, offscreen, xcb.

Reinstalling the application may fix this problem.

Aborted

root@colibri-imx6-egfls:~#

3

Then it seems you did not create EGLFS based image correctly. See the answer on this post. The instructions would also be applicable for Colibri iMX6.

4

Thank you sanchayan.tx. I’ll repeat image creation.

5

While creating EGLFS console-trdx-image did you follow the instructions as per this article.

Is your helloworld application a QT widget based application? Does it work if you execute it as below

./helloworld --platform eglfs

Without specifying the above it would look for Qt platform plugin “xcb” and default X display.

6

Please note the following Every time one changes the DISTRO_FEATURES, one has to remove all build output and sstate cache, in our setup remove the directories build/out-glibc and build/sstate-cache, if present from any previous build.