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warning using eglfs on a raspberry pi 4 with a yocto distro & performance issue



  • Hi all. I'm getting my head around using a custom yocto build of linux with QT. I'm playing around, learning how I'd develop a QT gui application for a device. I've added QT to the yocto image, and have used the generated SDK to compile some simple qt terminal and gui applications. I created a test gui with some sliders and knobs, but I get the following warnings on execution:

    XDG_RUNTIME_DIR not set, defaulting to 'tmp/runtime-root' ( thought this was because I ran as admin, so added my user to video group so I didn't need admin, but the warning persists)

    Couldn't get V3D INDENT0: no such device (couldn't find anything about this error at all!)

    Setting Framebuffer is only avalible with DRN atomic API

    Attribute QT::AA_ShareOpenGLContexts must be set before QCoreApplication is created.

    app seems to run fine anyway, but the performance is terrible. Moving a slider or knob at all pins the cpu at 100% and takes about a second to complete the frame update. Could this be related to some of the warnings?


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