Hello,

i have the problem that when i switch back from a virtual terminal to KDE, i just get a black screen. I have to stop Xorg and restart it again to resolve this. This problem happens when i use the NVIDIA propriatary driver. I had this happen on 2 different machines, on different distributions (one machine has a NVIDIA GT 640 and the other one a GT 520). I was wondering if anyone else has this problem, because i could not find much about it (sorry if i overlooked something).
This bugreport seems to be related to the problem, since this sometimes also happened, when some program switched the resolution of the screen (my virtual terminals are set up to use another resolution than the desktop): https://bugs.kde.org/show_bug.cgi?id=325025 . The problem only occurs with the propriatary driver not nouveau.

Greetings
Björn

distribution? version?
version of Nvidia drivers? self compiled or binary from distribution?

I had the problem on Gentoo with NVIDIA driver version 343.36 and Linux Mint 16. On both versions it was the driver from the official distribution repositories.

I don't think this is a KDE issue based on this Google search https://www.google.com/search?client=op ... %22+nvidia

This result says its a lack of a UEFI compatable Nvidia driver https://bbs.archlinux.org/viewtopic.php?id=178984 and
some results also talk framebuffer

Not savvy enough to help but think you should try the Nvidia Linux forum and/or one of your distributions

ps - you could try the 346.xx driver but may need to compile it

run

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dmesg | grep NVRM

If this yells a warning about not using a VGA console:

[ 2.795733] NVRM: Your system is not currently configured to drive a VGA console
[ 2.795735] NVRM: on the primary VGA device. The NVIDIA Linux graphics driver
[ 2.795736] NVRM: requires the use of a text-mode VGA console. Use of other console
[ 2.795737] NVRM: drivers including, but not limited to, vesafb, may result in

see eg. https://wiki.archlinux.org/index.php/GR ... ramebuffer on how to fix that.

@google01103:
Thanks. It might not be a problem with KDE, but it only happens with the combination NVIDIA <-> KDE. I currently have Xfce installed and no problems with this setup. Also, my old board didn't run UEFI, so it also happens on BIOS systems. I will look further into it tomorrow. I think it might have something to do with the video mode the virtual terminal runs on.

@luebking
Thanks, i will try this out and post the results.

Hello,

forgot to post yesterday, these are my results:
I've tested with 3 different driver versions: 340.65 (newest version on NVIDIA website), 343.36 (stable version in Gentoo repos) and 346.22 (unstable version in Gentoo repo).
343.36: Was the driver I used by the time of making this post, gives me the problems explained in first post
346.22: Actually fixed the problem with terminal switch, but gave me a black screen on resume from suspend
340.65: Terminal switch doesn't work, but resume does.

And i've discovered another thing: When i deactivate compositing, everything works. Also, if I get the black screen I can make it work again by toggling compositing (ALT + SHIFT + F12).

So, the solution I've gone with, at least for the moment, is I've installed 340.65 and try to remember to turn off compositing, whenever i want to switch to a virtual terminal (rarely happens). Still, it would be nice if everything would work.
What strikes me as odd is that nobody except me seems to have that problem, or they just don't notice it, because they never use virtual terminals.

I have to say, I'm disappointed with NVIDIA. When the driver works, it gives me a wonderful graphical performance, but it seems that it breaks in almost every setup that you can come up with. And the only way to get it to work is to reduce yourself to a very plain desktop experience, which you could also get with the fbdev driver lol.

So, if you have any more ideas I'm still interested in fixing that problem, but for me it works at the moment and I can finally enjoy KDE .

Did you check whether you're using a framebuffer console? ("dmesg | grep NVRM")

Hi,

sorry, forgot to post this yesterday. This is the output from the command:

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[    6.706717] NVRM: loading NVIDIA UNIX x86_64 Kernel Module  340.65  Tue Dec  2 09:50:34 PST 2014

Looks like everything is set up properly to me.

No fb console, no - that's fine.

Can you post the output of "qdbus org.kde.KWin /KWin supportInformation" (when the compositor is running)

Sure, here is the requested output: https://paste.kde.org/payvlfziu

> Qt Graphics System: native
Try to set this to "raster" ("kcmshell4 kwincompositing", 3rd tab)

> glPreferBufferSwap: 0
Ok, so you've turned off v'sync: was it because of the present issues or due to sth. else before?
(Not sure what might happen if we keep swapping on a non blocking glSwapBuffer...)

> OpenGL renderer string: GeForce GT 520/PCIe/SSE2
Actually the same GPU here, but on 3.1.0 NVIDIA 343.36

Since I'm using the core profile (GL 3.1) but you're not:
> glCoreProfile: false

I wonder why your driver announces GL 4 ....
> 4.4.0 NVIDIA 340.65

-> you could try on the core profile as well.

luebking wrote:> Qt Graphics System: native
Try to set this to "raster" ("kcmshell4 kwincompositing", 3rd tab)

OK, i will try that tomorrow

luebking wrote:> glPreferBufferSwap: 0
Ok, so you've turned off v'sync: was it because of the present issues or due to sth. else before?
(Not sure what might happen if we keep swapping on a non blocking glSwapBuffer...)

I turned this off to see if it helps.

luebking wrote:Since I'm using the core profile (GL 3.1) but you're not:
> glCoreProfile: false

I wonder why your driver announces GL 4 ....
> 4.4.0 NVIDIA 340.65

-> you could try on the core profile as well.

Does that mean, that i should change to OpenGL 3? I have it on OpenGL 2 at the moment.

Does that mean, that i should change to OpenGL 3? I have it on OpenGL 2 at the moment.

"You could try."
I just wonder because the supportInformation tell me

OpenGL version string: 3.1.0 NVIDIA 343.36

The GL version here matches my setup while yours suggest the maximum capability (but your driver version is a bit older as well, so this may be the only cause)