Subject: [K12OSN] kvm switch

Chuck Kollars ckollars9 at
Sun Jun 15 04:10:21 UTC 2008

> Does the 5-EL version support kvm switches? 

My understanding is the goal of the current generation
of UI switches is to do it's job without the system
(including the software) ever realizing a switch is
even there. (Which makes sense when you consider
you've never seen a "device driver" for a KVM switch.)
They'll fake the presense of a mouse when the real
mouse is switched away to something else, some of them
will even fake a response to a screensize query when
necessary, and any special functionality is just
between the keyboard and the switch with no software
on and no involvement by the computer. Generally this
generation of devices is identified by the term "KVM" 
...which wasn't used for earlier generations if you
can remember back that far. 

Even so it's usually a good idea to switch the display
to a system before rebooting it, so the system always
boots up with "real" hardware there and never depends
on the KVM fakes. And a few systems may get the wrong
idea about screen size no matter what when a KVM
switch is in the path, and I don't know of any general
solution. (Sometimes you can "force" the system
configuration to use a certain screen size rather than
query the hardware, which will work fine until you
change out the monitor.)

Many KVM switches have some sort of "maximum
resolution", and won't allow the system to set the
monitor to a higher resolution no matter what (or if
they do allow it, it won't work right as the screen
will be distorted, perhaps so badly you can't even
read it). But that's a function of which KVM switch,
not of the OS. Most KVM switches I've seen are good at
least to 600x800 and usually to 768x1024, but beyond
that many poop out. 


-Chuck Kollars


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