Display corruption on KDE 4.12.2

Duncan 1i5t5.duncan at cox.net
Mon Feb 24 12:29:18 GMT 2014

Steven Ulrick posted on Mon, 24 Feb 2014 04:03:11 -0600 as excerpted:

> Hello, Everyone I am running a fresh install of Fedora 20 with version
> 4.12.2 of KDE.  This is the version that is currently in Fedora 20's
> official updates.  I am having really annoying issues with display
> corruption.
> Here is a screenshot of the offending manifestations:
> http://afolkey2.us/gallery3/index.php/Assorted/Fedora20-

Please don't post HTML to the mailing list.  You did post a plain-text 
version as well, but a lot of regular's personal policy is that if a 
message must be HTML in ordered to be worth reading, it's not worth 
reading, and if it doesn't need to be HTML in ordered to be worth 
reading, why send it in HTML when a plain text version does just as well?

Meanwhile, to that link I can't connect.  Firefox times out.  afolkey2.us 
resolves to, which reverse-resolves to 
c-98-214-9-243.hsd1.il.comcast.net.  A tcptraceroute traces to comcast, 
up to freeport.il.chicago.comcast.net, to the destination IP... but keeps 
tracing with no-replies to hops beyond that.

Presumably a router at that address is black-holing, dropping TCP connect 
attempts to port 80 without replying with the usual CLOSED.  Are you sure 
you have your firewall set to let replies thru to your web server, and 
that your IP hasn't changed without the DNS resolution propagating such 
that I'm actually attempting to connect to another comcast customer?

> The corruption I speak of is always the color magenta.  The screenshot
> linked to above does not show it as being nearly as bad as it often
> gets...
> If I reboot, it will go away for a while, but it always returns.  In
> fact,
> I did a complete, fresh install just to make sure that my install of
> Fedora 20 wasn't corrupted some how.
> lspci shows my video card as being this:
> 03:00.0 VGA compatible controller: NVIDIA Corporation G94 [GeForce 9600
> GT] (rev a1)

What drivers are you running?  nVidia has a history of not cooperating 
with freedomware Linux driver authors and has forced them to reverse-
engineer the freedomware driver that many distros now ship, to decidedly 
mixed results.  nVidia does have a proprietary driver available to 
download, but while it is said to be quite good for gaming, there are 
other problems with it, including the fact that it taints the kernel due 
to its black-box nature, and the fact that you must rebuild the video 
driver after kernel updates since as a separately shipped closed source 
module it's not updated in sync with the kernel.

So some people will download and run the proprietary driver, while others 
stick with the freedomware driver if it works well enough on their 
hardware, and still others (like me) refuse to touch nVidia for graphics 
since it refuses to cooperate with the freedomware Linux community.

Anyway, such corruption is almost certainly video driver related.  Either 
change out your graphics, or try a different video driver, or possibly, 
turn down the video acceleration and/or disable effects that trigger the 

The only one of these that has anything to do with kde is the latter.  
Depending on the specific issue, it's possible that turning off the fancy 
effects or setting xrender instead of opengl mode will help.

In kde system settings, workspace appearance and behavior, desktop 
effects, on the general tab try disabling all effects and see if that 
helps.  If it does but that's too drastic for you, on the advanced tab, 
try setting compositing type to a lower opengl version or to xrender.  
Note that setting it to xrender will still disable many of the opengl-
requiring effects, but some effects will still work.  Also... it may get 
slower.  (If you wish you can try toggling individual effects on the all 
effects tab too, but that's left as an exercise for the reader, as they 

Other than changing graphics drivers, there's other options that can be 
set in files under /etc/X11/xorg.conf.d/, but that's really no longer a 
KDE problem but rather, one more suited to a fedora or xorg list or forum.

Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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