I bought an Aten CS1784A DVI+USB KVM switch a couple of months ago. I’m pretty happy with it except for one annoying problem.
It has a Dell multimedia USB keyboard plugged into it (picked it up from a swap meet for $15 – nice. it's a pretty good keyboard in its own right but i mostly bought it to match what I use at work), and a Logitech MX518 mouse connected. Also two computers – one runs Linux only. The other is switched off most of the time, but is occasionally powered up to boot into either Linux to experiment with stuff i don't want to do on my main system (like gnome 3) or sometimes Win7 to play games.
OK, that’s the background data. Here’s the problem
Whenever I reboot either of the Linux installations, the KVM stops recognising the keyboard. I have to unplug the keyboard and plug it back in before any input is recognised. Keyboard input doesn't get through to the currently active system, and I can't even use the KVM's magic key <ScrlLock><ScrlLock>n<Enter> to switch between systems – it doesn't even beep after the 2nd ScrlLock as it should, so it seems as if all keyboard input is ignored by the KVM, or the keyboard is totally confused and not sending anything. The mouse continues to work during this.
Rebooting Win7 doesn't do this. The keyboard just works as it should.
The problem occurs sometime between the time Linux is selected from the Grub2 menu and the gdm login screen is displayed (same result with both gdm on my main system and gdm3 on my secondary system).
The keyboard works when plugged directly into either system, without the KVM. I’d been using it for several months before I got the KVM, and I’ve tested that it still works correctly across a reboot if i plug it in directly.
Googling for "+linux +CS1784A" just gives me hundreds of pages from web sites selling the KVM, but no useful info.
Anyone seen anything like this before? Can anyone think of anything that linux might be doing in it's console or X initialisation that would confuse the KVM?
it's not a huge problem because I really don't reboot all that often – more of an annoyance that I'd like to go away.