Distortions on screen of UD-160 with Fedora 18


I experience distortions when I attach the UD-160-M after the upgrade to Fedora 18. It worked until the moment I upgraded.
Now, I get the login screen, but mouse is slow and the screen is not painted correctly. The mouse pointer leaves traces…
I have found no real clue in the logs…


Hi Wolfram,

Thanks for the report! Much is different in F18 (including new udl DRM driver).

Quick question: does the problems go away in gnome fallback mode? (Search for gnome fallback on Plugable.com for background)



Hi Bernie,
Thank you for your quick reaction. As it happens already at the login screen I have tried to add the login fallback dbus change.
At first, I get the KDE loginscreen, where my main screen shows the Gnome one. And usually I use mate.
I have tried to find out, if a driver is missing or used instead of the right one. I failed until now: lsmod shows udl, drm_usb, drm_kms_helper in use. Before I installed modesetting it did not work at all. Its like using an old unaccelerated driver.
Do you have a list of required packages and drivers that must be loaded?

The x log shows only one error:

  • Failed to initialize GLX extension (Compatible NVIDIA X driver not found)

In var/log/messages I have found nothing very special beside, maybe, this:
dbus-daemon[1576]: dbus[1576]: [system] Rejected send message, 2 matched rules; type=“method_return”, sender=":1.2" (uid=0 pid=1565 comm="/usr/lib/systemd/systemd-logind “) interface=”(unset)" member="(unset)" error name="(unset)" requested_reply=“0” destination=":1.248" (uid=42 pid=6149 comm="/usr/bin/gnome-session --autostart /usr/share/gdm/")

Is this related?
How can I help?


Hi Wolfram,

Thanks for the additional info. Its sounds like things are a bit off the beaten path there. When you did the upgrade to Fedora 18, how did you do it? I haven’t tried FedUp, and am not sure that’ll work …

The multiseat support in Fedora 18 only works with the (main) Gnome 3 spin. Perhaps the upgrade path from F17 is messy, without a reinstall on F18?

There are unfortunately many scenarios with the different spins and upgrade paths.



Hi again, I have tried fedup and ran into a broken system. After longer waiting and reboot I was back in F17 but without a desktop. I managed to come back to normality by doing a yum distro-sync.
Now everything else seems to work as usual. The only issue I have found so far, is that my second seat is not working. This issue here.
I guess a checklist, which modules should be used and which not would bring us closer to our target.

Edit: Obviously the setup is using the nvidia drivers. I have removed them from my system and the distortions were gone, leaving me at a very slow refresh rate.
So I guess, the reason is to be found in the xorg or nvidia drivers…


Hi Bernie,
my problem reduces itself more and more to when I try to use the thin client: my remaining problems happen after I connected the client via USB. I think it has to do with the x-server or something with a missing/wrong driver.
Can you please give me a list of drivers that need to be installed / used to drive this device, please?
My current state: The login screen appears and most features work. But, especially when the GUI is modified smoothly by resizing etc. There are remaining distortions, small stripes that are not painted correctly. It is quick, and works, but these stripes and remainders from the mouse pointer disturb us.
Also the error messages in messages log and xorg log are still there. Finally they end in a XServer that does not restart if you logoff to change the user.
Thank you!


Hi Wolfram,

Sorry I didn’t reply earlier - as far as I can tell, these screen artifacts are rendering issues with the new DRM graphics drivers (from F17 to F18 the graphics drivers switched from the fbdev framebuffer driver udlfb to the DRM driver udl).

I’m assuming that future kernel versions with updated DRM drivers will have these problems resolved. But I’m not certain, and can’t confirm yet.

I’d be on the lookout for kernel updates, as Fedora offers them.

Sorry for the mixed news, but hope that helps!