Re: [Xen-devel] same device accessed by different domains

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I guess there is only one backend driver for all the DomUs...
>
> Read more at Xen Intro - Backend drivers
> <http://wiki.xensource.com/xenwiki/XenIntro#head-f812265f11277c6b2c3a10c94d
>b485758e37e2bb>

There's only one backend driver for a particular device type in a particular 
domain.

So for instance, there's only one blkback driver running in a domain that 
provides virtual block device access.  There's also one netback driver in a 
domain providing virtual network device access.  dom0 only has one blkback, 
one netback...  but they can connect to multiple domU frontends.

If you are using driver domains, then you might have "dom0" running a blkback 
that provides access to the block devices dom0 controls.  But you might also 
have "driver domain 1" running a blkback that provides access to the block 
devices that driver domain 1 controls.

Because a real device can only belong to one domain, there will only ever be 
one blkback sending requests to any device in the host system.

Does that help?

Cheers,
Mark

> -Kaushik
>
> Amit Singh wrote:
> >   Hi all,
> >
> >         If same device is accessed by different domains(domU) please
> > let me
> >  know the same backend drivers is used to multiple requests from
> > different DomUs,
> > or for each individual request there is a frontend at domU site and
> > there is
> > corresponding backend driver at Dom0 ?
> >
> >
> >
> >  Regards:
> >
> >  Amit
> >
> > ------------------------------------------------------------------------
> >
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-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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