[geeks] KVM revisited

[Joshua D. Boyd]

On Tue, 2007-10-02 at 12:17 -0400, Charles Shannon Hendrix wrote:

> People say that if you do not have the KVM focused on the unit when you boot
> it, it sets video to a maximum of 1024x768.
> 
> Another common complaint is that none of the DVI KVM makers will issues
> fixes, in spite of having a firmware upgrade port on their boxes.
> 
> Is it really that difficult an engineering problem to have the unit allow
> video mode switching?  If nothing else, why can't it just pass the signals?
> Monitors seem to have no problem at all with resolutions changing as cables
> are plugged and unplugged, so it almost seems like the KVM makers are trying
> to be too clever.
> 
> I suppose maybe with DVI is has to get a response from the "monitor"
> indicating the signal is working, so the KVM must pretend to be at a
> certain resolution.  That's all I can think of as a reason for being
> this way.

Sure, the DVI needs to get a response from the monitor.

But why can't the KVM get that response from the monitor and save it to
send to the various computers hooked up to it?  In other words, the when
the graphics cards makes a DDC query, it would be talking to the KVM
rather than the monitor.

This is a problem with linux machines, OS X, and my VGA KVM, except it
defaults to 640x480 or 800x600 rather than 1024x768.  Although on linux
it is possible to force Xorg to a specific resolution even if it thinks
the monitor can't handle that.  In the next version of Xorg, the linux
trouble should go away.