[kwlug-disc] Switch between monitors

Chris Irwin chris at chrisirwin.ca
Thu Apr 5 11:19:00 EDT 2012

On Wed, Apr 4, 2012 at 16:43, unsolicited <unsolicited at swiz.ca> wrote:
> Just lean over and turn off the monitor in front of you when desired - I'm
> assuming you'd have to change inputs on the TV to effect, so same thing, in
> essence, there.

At the moment, I don't plan on having any other inputs connected to
the TV, though that may change. I'm currently trying to plan my

I'm finishing the room for use as an office. I've got my (linux-only)
laptop I use for most things, and my (windows-only) PC that is used
solely, completely, 100% for games. I currently have two monitors, and
will be adding a TV to the wall. My idea was:

* Laptop has built-in primary display
* Gaming PC directly connected to right-side monitor.
* Both machines connected to KVM for secondary display.

* KVM connected to magic switch (DVI or maybe HDMI will work?).
* Magic switch toggles KVM's output between Left-side monitor and TV.

Workflow-wise, if I'm working on something interesting on my laptop, I
can have two displays attached. If I want to watch a video, I can
throw the second output to the TV and sit back on my couch.

Likewise, there are times when a second display on the gaming machine
would be handy (particularly when installing mods and patches, etc).
I'd also like the ability to throw the game display to the TV (for
example: Driving games with my steering wheel). I'd also have to
switch "Primary" monitors in Windows, which is a manual process.

The ideal solution would be a box that I could connect multiple inputs
and multiple outputs so I could redirect any input to any output. If
such a box exists, I'm sure it is out of my price range. I was
half-way considering making a housing to hold 8 HDMI connectors, and
trying to find a few small ~15cm HDMI cables to manually patch (like
an old telephone operator), and using my KVM only for USB switching.

If anybody knows where to get 15cm HDMI cables, I'm listening.

> As best I remember, KVM's are such commodities that you may find such
> cheaper than a real video switcher. Get one with a button (not just
> keystroke switching), and forget the K and M parts?

I've got a pretty decent 4-port DVI+USB KVM currently, which I have
connected to my desktop and laptop. I was under the impression that I
couldn't reverse a KVM as the "PC" side exposes a fake monitor when
disconnected, suggesting it is not just a dumb passthrough.

> However, warning: 2nd monitors are addictive. If you have the ability for a
> second monitor, now or in the future, you will likely want both monitors at
> the same time. For some amount of time.

Yes. Unfortunately my laptop only allows one external monitor, so it
is either screen or tv, not both.

> Doesn't mean you have to use both monitors all the time. Although it is
> disorienting when your mouse pointer disappears, and you can't for the life
> of you figure out where it went. (If you really want to confuse someone with
> 2 monitors, sneak in and change the order in Xrandr - reverse which is left
> of which.)

I wish I could use xrandr. Nvidia laptop, so xrandr doesn't work with
the closed drivers, and nouveau isn't quite there yet.

Chris Irwin
<chris at chrisirwin.ca>

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