Gnome Classic desktop issue

[music_man1352000]

Hello everyone

I'm not quite sure how to describe this problem properly (which makes it difficult to search for solutions), so I'll let the screenshots describe and add the technical details that are required.

I have a dual 22" 1680x1050 monitor system running Ubuntu 12.04 64 bit.
The GPU is an NVidia GT 520 with DVI, HDMI and VGA outputs.
I'm using the "release" version binary NVidia driver (295.40).

Up until yesterday I had been using this system without problem with the DVI and VGA outputs. Yesterday I tried to hook my laptop into this system using a KVM to switch one of the screens between laptop and desktop. This seems to have been the beginning of my problems.

The KVM is a 2xDVI input, 1xDVI output KVM. I connected the HDMI output on the 520 directly to one of the screens using an HDMI to DVI cable. The DVI output on the 520 is connected via a standard DVI cable to the KVM, then the KVM output is connected via another standard DVI cable to the other monitor.

This change required me to run nvidia-settings to reconfigure. I configured for "separate X screen" for each monitor and then restarted. One monitor is inactive until after I login, so I didn't initially notice a problem, however once I get to the desktop I get the issue shown in the screenshots.

One screen (the directly connected one using DVI to HDMI) is white with the Gnome classic panels at top and bottom. The other screen (connected to the KVM) is standard background with duplicated panels for workspace switching, "status" (chat, email, time, network etc.), "folders" (applications, places) and "taskbar" (application instances). It is like the desktop has been duplicated twice on the same monitor. Each time I log in, an additional set of pannels is added. As the desktop loads I also briefly see the white monitor flash with the proper background, but then it goes and stays white. Hopefully that makes sense.

At first I figured it might be a GPU or KVM issue (I did find that I couldn't connect the HDMI output to the KVM because of HDCP - monitor totally not detected). But then I reasoned that if VGA + DVI outputs had worked previously then surely DVI + HDMI should also be okay (ie. the GPU is capable). I did prove that the problem also occurs when I tried to revert to VGA + DVI with the KVM. I can also move my mouse and icons over the white desktop, although strange things happen - the screen is unusable though as I can't transfer windows to it.

I've had problems with xorg.conf in the past and I figure something may be wrong there again. However I also installed some updates using the update manager. Tried using the "post release" NVidia driver - didn't seem to help. Now I'm at the end of my [very limited] ideas, and I hope somebody with far more wisdom than I can extricate me from this mess!

Thank you in advance...


For reference, this is my xorg.conf:

root@storm:~# cat /etc/X11/xorg.conf
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 295.33 (buildd@allspice) Fri Mar 30 15:25:24 UTC 2012

Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" RightOf "Screen0"
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/psaux"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "kbd"
EndSection

Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "RXT V_2D1912-01"
HorizSync 30.0 - 80.0
VertRefresh 45.0 - 65.0
Option "DPMS"
EndSection

Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor1"
VendorName "Unknown"
ModelName "ViewSonic VX2240w-2"
HorizSync 24.0 - 82.0
VertRefresh 50.0 - 75.0
Option "DPMS"
EndSection

Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GT 520"
BusID "PCI:1:0:0"
Screen 0
EndSection

Section "Device"
Identifier "Device1"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GT 520"
BusID "PCI:1:0:0"
Screen 1
EndSection

Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "TwinView" "0"
Option "TwinViewXineramaInfoOrder" "DFP-0"
Option "metamodes" "DFP-0: 1920x1200 +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection

Section "Screen"
Identifier "Screen1"
Device "Device1"
Monitor "Monitor1"
DefaultDepth 24
Option "TwinView" "0"
Option "metamodes" "DFP-1: 1680x1050 +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection

[music_man1352000]

Gentle bump...
I'm still having problems with this so any advice would be much appreciated.

[music_man1352000]

Another bump...
I'm still stuck. Can nobody help?

[music_man1352000]

Okay, I'm going to answer myself again...

The solution can come quite quickly when you know what to search for. In desperation I searched for "nvidia white screen of death". Apparently the white screen indicates that a desktop manager is not running for that screen. The suggestion was to use "TwinView" instead of "separate X screen"... and that solved the problem for me. TwinView is not display cloning as the name would suggest - it is display extension. Could do with a rename if you ask me.

HTH

[madjr]

Okay, I'm going to answer myself again...

The solution can come quite quickly when you know what to search for. In desperation I searched for "nvidia white screen of death". Apparently the white screen indicates that a desktop manager is not running for that screen. The suggestion was to use "TwinView" instead of "separate X screen"... and that solved the problem for me. TwinView is not display cloning as the name would suggest - it is display extension. Could do with a rename if you ask me.

HTH

yes, twinview was also confusing for me last time I used an nvidia card...