[K12OSN] K12Linux F10 Display problem

Phydeaux reb at taco.com
Wed Feb 4 21:13:27 UTC 2009

At 03:58 PM 02/04/09, John Baillie wrote:
>We are still running K12LTSP release 4.2.1EL-1
>2 Servers with about 100 concurrent  users.
>This setup has served us well and has been hands off for three plus years.
>I plugged in the k12 live usb (pretty slick) and booted a few of the lab terminals with mixed results.
>We have a mixture of  CRTs and LCDs and some of them will not display.
>The clients are all Compaq DS51 and DS5S
>We ran into the same problem when we demoed the latest ubuntu a few months back.
>I'm guessing that the newer x servers don't work well with the older hardware we have and it has nothing to do with a particular distribution. It's looking like we will have to dig in and make some manual adjustments to the display properties.
>I'm looking around /opt/ltsp/i386/etc/X11 but it is not obvious where I should make changes.

I believe the problems have to do with autodetection of the display adapter. I
found that root of our problem was that the resolution of VGA monitors that
were connected with analog cables was not being properly detected.  This
caused issues mainly with the startup login screen.  The right hand part of the
screen was stretched across the whole monitor so that the login box was
barely visible.  Some users also experienced resolution problems after login.

For newer monitors and motherboards (x86_64), replacing the analog VGA
cable with a DVI cable solved the problem.  For our older i386 machines
(mainly with Intel 810 hardware on the motherboard), swapping out the ancient
CRTs for new flat panel displays (which was scheduled anyway) solved the

I'm not suggesting you obtain new hardware, just trying to provide a data point
regarding what and where the problem is.


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