[CentOS] blue screen instead of login screen

Frank Cox theatre at melvilletheatre.com
Thu Jan 12 18:56:40 UTC 2012

On Wed, 11 Jan 2012 22:55:36 -0600
Frank Cox wrote:

> This leads me to the conclusion that the problem can't be that any part of the
> gnome installation is missing because it works at the lower 1280x1024
> resolution.

Upon further investigation I think this problem stems from an unnecessarily
huge virtual screen, but I don't know how to change it.

When running at 1920x1024, if I switch to runlevel 3 and run startx I get
nothing but the blue background screen.  I can move the mouse cursor to the top,
the bottom and the right side of the screen, and it stops. But when I move it to
the left side of the screen, it disappears and seems to keep right on going.
Unfortunately, the screen itself doesn't scroll to follow it; nothing moves at

However, I just discovered something really interesting.  I mentioned before
that I can get the desktop working fine at 1280x1024 by using the "nomodeset"
kernel parameter.  So I created a couple of directories on my desktop at the
1920x1080 resolution by right-clicking on the desktop background and selecting
"Create Folder".  I put the directories more-or-less in the middle of the
visible desktop.

Then I rebooted the machine with the nomodeset kernel parameter and logged into
the lower-resolution desktop (where I get all of the usual menus and icons and

And... The icons for those directories were half-showing on the extreme right
of the desktop, near the top of the screen.  Only about half of the actual icons
showed, the rest was cut off by the right edge of the screen.

This indicates to me that the virtual screen is somehow much larger than the
actual screen and that's what's causing the problem.

I added "Virtual 1920 1024" to my 10-monitor.conf file  and put that back into
the /etc/X11/xorg.conf.d directory and rebooted as usual (without the nomodeset
parameter) to see what would happen.  Nothing changed. gdm had no login window
and if I switched to runlevel 3 and ran startx as my username I had my test
directory icons back in the middle of the screen and no menus or anything else.

I changed it to say "Virtual 1024 768" to see what would happen and again,
nothing changed.

I think this machine has a much larger virtual screen than the physical
screen.  How can I match the virtual screen size to the physical size?

Here is the 10-monitor.conf file that I've been experimenting with.  Note that
the computer works the same with or without this 10-monitor.conf file
in /etc/X11/xorg.conf.d, and there is no xorg.conf file in /etc/X11.

Section "Monitor"
Identifier "Monitor0"

Section "Device"
Identifier "Device0"
Driver "intel"

Section "Screen"
Identifier "Screen0" 
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 16
Modes "1920x1080"
Virtual 1920 1080

MELVILLE THEATRE ~ Real D 3D Digital Cinema ~ www.melvilletheatre.com

More information about the CentOS mailing list