Comment 17 for bug 812594

Spent some time testing openSuse, Ubuntu, Kubuntu based on 12.04 release and openSuse 11.4.
Unfortunately I couldn't get Fedora 17 working as described in this article http://www.phoronix.com/scan.php?page=news_item&px=MTA5NjY
None of them was able to display more than green screen.
Using hints from this topic I made one of diplaylink screens to get xlogin and xdesktop, though size was limited to 320x240.
IMO source of problem is located in X sever, which is unable to handle screen coordinates split between different kernel drivers. Xinerama in this case seems to not work.
Seems also that xrandr ignores existence of udflb devices.
That's why manual edit of xorg.conf or files in /etc/X11/xorg.conf.d gives partial success, sometimes.
Newer distributions are more difficult to handle, as thought to be "automatic" thanks to xrandr. BTW: on Kubuntu12.04 nVidia Xserver writes its own xorg.conf making xrandr for "read only".

I'm waiting for Ubuntu 12.10 having xserver-xorg-video-displaylink removed from distro. Maybe problem is solved there?
In the meantime I'm going to test Linux Mint 13 with KDE.

Greetings