Resolution issue with kvm switch

Josh Triplett josh at
Thu Jul 5 19:07:08 PDT 2007

Alex Deucher wrote:
> On 7/5/07, Tom Winterhalder <t.winterhalder at> wrote:
>>  I have several systems connected to a Level1 KVM switch. According
>> documentations this switch can handle resolutions up to 1920x1440.
>>  Now I have connected several Linux systems to this switch with different
>> graphic cards (ATI and Intel). Directly connected to my monitor (HP LP2465)
>> I get a resolution of 1920x1200 with all the systems. As soon as I connect
>> the systems to the switch and restart X I only get a resolution of
>> 1280x1024. Without restarting X, just connecting my systems to the switch I
>> still have the resolution of 1920x1200.
>>  Looking into the log files I can see, that the switch is reporting to
>> display resolutions of up to 1280x1024. So it is clearly a problem of the
>> switch not reporting correctly its capabilities. As I have no possibility to
>> upgrade the firmware of this switch I wonder if there is a way to override
>> these settings in xorg.conf.
>>  I already tried different Modelines and Mode settings without any success.
>> Can anyone help me solving this issue?
> Add a monitor section to your config with the appropriate sync ranges
> and modes for your monitor then specify the modes you want in the
> display sub-section of the screen section of your config.  That should
> do the trick.

In situations like this, I wonder if it would make more sense to have a config
option to say "when you go to obtain DDC information, read it from this file
instead".  In this case, that would allow the X server to use a copy of the
DDC information from the monitor when not running through the KVM switch, and
use it when running through the KVM switch.

Option "OverrideDDC" "/etc/X11/override.ddc"

- Josh Triplett

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