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Re: [Xen-users] Multi headed, Multi user partially virtualized environme

To: Simon Hobson <linux@xxxxxxxxxxxxxxxx>
Subject: Re: [Xen-users] Multi headed, Multi user partially virtualized environment - feasible?
From: Rudi Ahlers <Rudi@xxxxxxxxxxx>
Date: Sun, 10 Jul 2011 11:41:34 +0200
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On Sat, Jul 9, 2011 at 10:50 PM, Simon Hobson <linux@xxxxxxxxxxxxxxxx> wrote:
Rudi Ahlers wrote:

AFAIK a normal PC can only accept input from one keyboard and one mouse at a time. So your biggest challenge would be to figure out how to bind a mouse and keyboard to one specific VM, then another keyboard & mouse to another VM.

One would normally use a dumb terminal for each user who needs to connect in this case, so I'm not sure if what you want todo would be possible with today's hardware.

There's no such hardware restriction, and never really has been AFAIK. Even back when PS2 (and older) keyboards were in use, there wasn't (to my knowledge) any fundamental restriction that would have prevented multiple interfaces being supported. Now it's all USB it's moot anyway - you can add something like 60 keyboards and mice (limit is 127 devices total IIRC).

With "hardware limits" I wasn't referring to how many USB ports your PC had, but rather how many input devices it can recognize :)
Connect 5 USB keyboard to a PC, then go into the BIOS and see which one works? They all do the same thing, you can't isolate which one can access the BIOS and which one can't. 
And the same goes for graphics cards. Even if you have 3 installed and 6 monitors connected to it, either only one (generally the on-board of first PCI-E) card will display something, or they'll all display exactly the same thing.

If there was a way to boot into the BIOS with one keyboard and monitor, yet display & manipulate the boot prompt from another keyboard and monitor, then it would be rather easy to tell the OS which device it should use. 

The real problem is, as you say, in software/OS support to route devices to VMs.

Referring to my above comments, this is "maybe" where something like VirtualBox could help. There's an option in VirtualBox to allocate specific USB device (generally storage) to a VM - so I don't know if you could limit a certain keyboard, mouse & graphics card (or rather VGA port) to a specified VM that way around?


Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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Kind Regards
Rudi Ahlers

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