Crash with discrete GPU

[lissalissa]

Hello friends,
I am attempting to run flightgear on my Fedora 36 system with an nvidia 1650 TI GPU. The last time I tried to use flightgear was about a week ago, at which time there were no issues. Now, when I right-click on Flightgear and click run with discrete GPU, the icon briefly pops up in my dock and then crashes and exits. If I run flightgear using my integrated GPU, this does not occur.
I'm not sure how to run with my discrete GPU via command line so I'm not sure if there are specific errors popping up.
Any help troubleshooting would be much appreciated.

[lissalissa]

Update:
I'm able to glean this error from the terminal now: QSocketNotifier: Can only be used with threads started with QThread
But that same error comes up when I run with the integrated GPU only without the crash, so this doesn't seem to be the fatal error.

[lissalissa]

Further troubleshooting information:
If I run fgfs with a discrete gpu from terminal, no issues. The crash only occurs with the --launcher flag.

[erik]

In the launcher under Settings, and Additional settings at the bottom, there is an option "See the final set of arguments that will be used."
Could you copy that and use it at the command line to see if that causes the crash too?

Or do you not even get to the point where you can hit "Fly"?

Erik

[lissalissa]

It crashes before the launcher even appears.

[wkitty42]

self-built FG or downloaded from somewhere? if downloaded, where, exactly, did you get it? it sounds like it was built without Qt or you don't have the (proper?) Qt libs installed...

[lissalissa]

Installed from the fedora rpm repository. Ran fine a few days ago. Runs fine currently on integrated GPU. Runs fine if I try to launch fgfs without the --launcher option. I think this started after a kernel update, but that may be a coincidence. My GPU is working fine for other applications.

[TheEagle]

Run "gdb --args fgfs --launcher". You'll be taken to a custom command line interface. There just type "run" and after it crashed type "bt all" (or was it "bt full" …) then press "c". You should get a list of backtrace items - please copy that and paste it here inbetween

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 and

tags. That might give us a clue what it is crashing on.

[lissalissa]

The back trace gives me:

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no stack

But earlier, gdb spits out:

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gui        The Wayland connection experienced a fatal error: Protocol error

[lissalissa]

Further testing based on that error confirms that this is only reproducible on Wayland. When I run an X session the crash does not occur. So this is a wayland issue. Not sure where to go from here other than to use X. I don't really have a strong reason to stick to Wayland.

[TheEagle]

That's already something ! Please run FG like this:

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WAYLAND_DEBUG=1 fgfs --launcher


and post what it spits out.

[lissalissa]

Aha!
The relevant bit it spits out is:

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wl_display@1.error(nil, 7, "failed to import supplied dmabufs: Arguments are inconsistent (for example, a valid context requires buffers not supplied by a ")

I can provide the full output if that's helpful somehow.

[TheEagle]

Well, I'm not a Wayland specialist nor a wayland user myself, so I guess we should wait and see if anyone else can reproduce this and then file a bug for the maintainers of the Wayland server - I don't think that this bug is caused by FG itself.

[erik]

NVidia and Wayland is a complex situation. So this sounds like either a bug in Qt, Wayland or the NVidia driver.
Sadly nothing we can do anything about.

Erik