Hello all,

since this update, there is no option xrender for the plasma's compositor anymore. This is a big problem for Monitors with Screen resolutions 5120x1440. If you logged in the deskop, and move some inputdevice, you have only an transparent blue screen, like a bleu steam over the whole deskop. I have here an Nvidia RTX2060 Super with actual driver.

The only workaround is to start with SDDM with the resolution 3840x1080, after login the resolution will be changed for plasma to navtiv 5120x1440. The problem on changing resolution in KDE is that on every login all widgets twirled around the desktop, squeezed and thrown into the outer corners. Thus, you have to set up the entire desktop anew every time you log in.

The behavior occurs as soon as you use the mouse. The keyboard does not cause the behavior. I have also replaced the mouse for testing.

So how can i enable the xrender composite again?

Best Regards
boospy007

You use wayland or X? Nvidia driver or Nouveau?

grumpfel wrote:You use wayland or X? Nvidia driver or Nouveau?

I'am using X with actual nvidia driver 470.74. I tested wayland too, and there this problem does not exist, but wayland cannot be used productively at the moment. No good performance.

Xrender use normally more for compatibility with old hardware. Normally your hardware support Open GL 3.0, so I don't see the necessity to use xrender

grumpfel wrote:Xrender use normally more for compatibility with old hardware. Normally your hardware support Open GL 3.0, so I don't see the necessity to use xrender

I would normally agree with that as well.

So i have build 2 Videos.
Video01.mp4: Start from logged in user account with desktopwidgets and the native resolution 5120x1440
Everything looks normal. So i logged out and you can see the sddm with the resolution 3840x1080, so if i reloggin again with this user, you can see all desktopwidges dissipate when changing the resolution to the native of 5120x1440. This is bad. Here i have this piece of xorg.conf:

Code: Select all

Section "OutputClass"
    Identifier  "nvidia"
    MatchDriver "nvidia-drm"
    Driver      "nvidia"
    Option "TripleBuffer" "True"
    Option "AllowEmptyInitialConfiguration"
    ModulePath "/usr/lib/x86_64-linux-gnu/nvidia/xorg"
#    Option "metamodes" "5120x1440 { ForceFullCompositionPipeline = On }"

The second video, Video02.mp4 start directly from sddm with native resolution 5120x1440. So the upper configline is activated. So after the loginprocess is ready, everything looks fine, if use the Keyboard, everything is fine, but as I use the mouse, the screen turns blue. So strange. I tested a lot of x11 configurations and options, always the same result. This is also the reason why I want to use Xrender, because with it the problem does not occur.

I found the solution My colleague found a post on Reddit. That put me on the right track. This blue screen is caused by a wrong default setting of the desktop effects.

Highlight screen edge when approaching

may not be activated. With this, KDE does not cope properly with the resolution. Here is the screenshot from the setting.

In my environment, OpenGL has a severe screen lag, and after a while, the screen flickers and the mouse cursor proliferates, making it unusable.
If I uncheck "Enable compositor on startup" in the compositor settings, I can use it normally after system reboot in a state similar to xrender's behavior.

gatolabo wrote:In my environment, OpenGL has a severe screen lag, and after a while, the screen flickers and the mouse cursor proliferates, making it unusable.
If I uncheck "Enable compositor on startup" in the compositor settings, I can use it normally after system reboot in a state similar to xrender's behavior.

This is only legacy mode. Same as ALT+Shift+F12, Reboot is not needed. Between this and xrender are worlds.

What graphic card do you have?
What xorg.conf?
What driver?
Maybe do you use wayland and not X?

What graphic card do you have?
What xorg.conf?
What driver?
Maybe do you use wayland and not X?

Operating System: KDE neon 5.23
KDE Plasma Version: 5.23.1
KDE Frameworks Version: 5.87.0
Qt Version: 5.15.3
Graphics Platform: X11
Processors: 4 × Intel® Pentium® CPU N3700 @ 1.60GHz
Graphics Processor: Mesa DRI Intel® HD Graphics 405

No /etc/X11/xorg.conf

$ egrep -i "Video|Driver" /var/log/Xorg.0.log
[ 13.353] X.Org Video Driver: 24.1
[ 13.353] X.Org XInput driver : 24.1
[ 13.409] (==) Matched modesetting as autoconfigured driver 0
[ 13.409] (==) Matched fbdev as autoconfigured driver 1
[ 13.409] (==) Matched vesa as autoconfigured driver 2
[ 13.410] (==) Assigned the driver to the xf86ConfigLayout
[ 13.410] (II) Loading /usr/lib/xorg/modules/drivers/modesetting_drv.so
[ 13.414] Module class: X.Org Video Driver
[ 13.414] ABI class: X.Org Video Driver, version 24.1
[ 13.415] (II) Loading /usr/lib/xorg/modules/drivers/fbdev_drv.so
[ 13.417] Module class: X.Org Video Driver
[ 13.417] ABI class: X.Org Video Driver, version 24.0
[ 13.417] (II) Loading /usr/lib/xorg/modules/drivers/vesa_drv.so
[ 13.419] Module class: X.Org Video Driver
[ 13.419] ABI class: X.Org Video Driver, version 24.0
[ 13.419] (II) modesetting: Driver for Modesetting Kernel Drivers: kms
[ 13.419] (II) FBDEV: driver for framebuffer: fbdev
[ 13.419] (II) VESA: driver for VESA chipsets: vesa
[ 13.441] ABI class: X.Org Video Driver, version 24.1
[ 14.108] (II) modeset(0): [DRI2] DRI driver: i965
[ 14.108] (II) modeset(0): [DRI2] VDPAU driver: va_gl
[ 14.122] (II) Initializing extension XVideo
[ 14.122] (II) Initializing extension XVideo-MotionCompensation
--Omitted below--

The graphics card is really not suitable for such requirements. Xrender would have been your last hope. It's best to buy a decent computer and a current graphics card