As far as I know, the KVM switching should be hardware triggered. It should not be related to X at all because it does not require any software at all. If it did, then you wouldn't be able to switch inputs when no computers are attached.
-milki On Wed, Jan 18, 2012 at 20:07, Todd Pytel <tppy...@sophrosune.org> wrote: > Hi all, > > I'm digging around at a quirk involving Scroll Lock and KVM switching > that I think X is responsible for and hoping someone here can explain > it. At this point I can work around it myself. But I'd really like to > understand it, or perhaps provoke a change to make it work better for > others less inclined to dig at this than I am. > > Like many other KVM's out there, mine triggers switches through double > Scroll Lock taps. This has often required some fiddling to get working > properly in the past, usually by adding Scroll_Lock to mod3 using > xmodmap. But sometime recently, (I think) something changed in X11's key > handling. A while back, my GNOME desktop stopped switching on Scroll > Lock (even with the xmodmap) but still switched on Num Lock. Then it > stopped working entirely in GNOME, XFCE, or Openbox. > > What I found after poking around some more tonight is that I can get the > KVM trigger working by twiddling the LED's with xset... > > xset led 3 && sleep 0.2 && xset -led 3 > > That toggles the LED's and triggers the KVM. > > In some sense, this solves my problem. I can put that in a script and > bind it to a key. But I'd like to actually understand what's going on. > Also, since Scroll Lock is the most common KVM trigger, it would be nice > to fix this so that it "just works" for people with less enthusiasm for > this sort of detective work. It seems like this shouldn't be an > earth-shaking architectural change, but I admit I don't know jack about > the internals of X. > > Specifically, here's what I see on Debian Sid... > > 1) In the console, Scroll Lock and KVM switching work properly with no > tweaks. > > 2) In an untweaked X session, the Num Lock LED works while the Scroll > Lock one does not. Both keys register in xev output. > > 3) After "xmodmap -e 'add mod3 = Scroll_Lock'", the Scroll Lock LED > works. But it still doesn't trigger the KVM. > > 4) Even without the xmodmap line, twiddling the LED's via xset both > toggles the LED's and triggers the KVM. > > What I'd really like to understand is what's different internally > between toggling the LED via xset and doing it through an xmodmap'd > Scroll Lock. Clearly the KVM is seeing those events differently and I > don't know enough about X to understand why. > > If it's not too much of an undertaking, I'd also suggest that Scroll > Lock should work as expected, or at least have an easy xorg.conf option > to make it work as expected. A little Googling will show a decade's > worth of posts across the web from KVM users trying to get their boxes > to switch properly. And since the old xmodmap solution doesn't work > anymore, it would be helpful to have a solution that doesn't involve > hacky scripts and keybinding. > > Cheers! > Todd > > _______________________________________________ > xorg@lists.x.org: X.Org support > Archives: http://lists.freedesktop.org/archives/xorg > Info: http://lists.x.org/mailman/listinfo/xorg > Your subscription address: nitesha...@gmail.com > -- Hope is a dimension of the spirit. It is not outside us, but within us. When you lose it, you must seek it again within yourself and in people around you -- not in objects or even events. - -Vaclav Havel
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