Could not open egl display

[srakitnican]

I am trying to package grefsen on Fedora 25, I'm able to run it successfully from gnome, but not from a VT.
I tried to modify QT_QPA_PLATFORM with a couple of options without success, any option I tried gives similar error message that it can't open or connect to a display. Options I've tried: eglfs, wayland, xcb
, offscreen . Error messages are like: Could not open egl display or QXcbConnection: Could not connect to display.

What could be the cause for these messages?

[ec1oud]

Permissions maybe? /dev/dri/card0 is in the video group on my machine, so I added myself to that group.

When it says QXcbConnection: Could not connect to display that's different of course... you shouldn't see that with eglfs anyway (although there was a time that it was happening to me too - I think it was a bug in dev branch a couple years ago). You should use the eglfs plugin on the console. Wayland is for client applications, not for the compositor.

You should be able to run any Qt application on the console with the eglfs plugin (assistant -platform eglfs for example, or qml -platform eglfs test.qml).

[srakitnican]

Adding my user to the video group did not help. By looking at ACL my user already had +rw access to /dev/dri/card0. I've generated stacktrace.txt, does this tell you something useful?

I am using Qt 5.7.1 as available from Fedora. Yes you are right, I am seeing QXcbConnection: Could not connect to display only with default (xcb?).

Not sure how to make use of last suggestion, I have to investigate that a bit more.

[srakitnican]

Same thing happening with /usr/lib64/qt5/bin/qml -platform eglfs, no qml files necessary to trigger error message. What could that mean?

[ec1oud]

I'm getting it too now on Arch, after a round of package updates. Maybe mesa changed something? I've got mesa 17.0.1 now.

But weston still runs on the console. And no Qt app does. Not even older versions of Qt. So this may be now a Qt bug I guess, but probably caused by something external... it was really working before.

[peeterm007]

I am getting the same error on fedora 25. I enabled debug msgs for qt, this shows the following:

---

qt.qpa.egldeviceintegration: EGL device integration plugin keys: ("eglfs_kms_egldevice", "eglfs_kms", "eglfs_x11")
qt.qpa.egldeviceintegration: EGL device integration plugin keys (sorted): ("eglfs_kms", "eglfs_kms_egldevice", "eglfs_x11")
qt.qpa.egldeviceintegration: Trying to load device EGL integration "eglfs_kms"
qt.qpa.egldeviceintegration: Using EGL device integration "eglfs_kms"
qt.qpa.input: udev device discovery for type QFlags(0x10)
qt.qpa.input: Found matching devices ("/dev/dri/card0")
qt.qpa.eglfs.kms: Found the following video devices: ("/dev/dri/card0")
qt.qpa.eglfs.kms: Using "/dev/dri/card0"
qt.qpa.eglfs.kms: Opening device "/dev/dri/card0"
qt.qpa.eglfs.kms: Creating GBM device for file descriptor 5 obtained from "/dev/dri/card0"
Could not open egl display

Similar error shows when launching a simple qml file with -platform eglfs.

On the other hand, I can start weston and kmscube. So is it possibly qt that is at fault?

It would be very interesting to get grefsen working.