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Re: [Xen-devel] Virtualization project idea

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Virtualization project idea
From: Gianni Tedesco <gianni.tedesco@xxxxxxxxxx>
Date: Fri, 27 Aug 2010 19:26:00 +0100
Cc: David Markey <admin@xxxxxxxxxxx>, Dhananjay Goel <dhananjaygoel123@xxxxxxxxx>, James Harper <james.harper@xxxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On Fri, 2010-08-27 at 10:57 +0100, Keir Fraser wrote:
> On 27/08/2010 10:48, "Dhananjay Goel" <dhananjaygoel123@xxxxxxxxx> wrote:
> >> You don't necessarily share network, disc, or mouse/keyboard at the USB
> >> level. For network, as an example, the hardware device belongs to the host
> >> which provides NATed or bridged networking to VMs. VMs see a virtual 
> >> network
> >> device rather than the underlying physical device. Similar principle 
> >> applies
> >> to other device classes -- VMs see a virtual device. If you want a VM to 
> >> see
> >> a property of a physical device that cannot be expressed in your virtual
> >> device model, you pass that physical device through directly to that one 
> >> VM.
> >> If you want direct passthrough and some semblance of sharing between VMs...
> >> that's harder to do.
> > 
> > I agree its difficult to do. But is it possible to do? Can we make such that
> > USB devices are shared across VMs? Any suggestion of how it can be done? 
> Well, no, not really. You go work it out and come back with some patches.
> :-)

You could do it at the USB class spec level I suppose, eg.
virtualisation layers for video, ccid, etc.. IOW it would be possible to
split a multi-slot smart-card reader in to several single-slot devices.
Or lets say a keyboard with an integrated microphone (or whatever) could
be split according to its separate well defined USB interfaces.

On the other hand, it's not clear any of it would be worth the lines of
code expended??


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