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Re: [Xen-devel] PCI Passthru: fn0 exported but not fn1

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] PCI Passthru: fn0 exported but not fn1
From: Stefan Neuwirth <neuwirt-xen-devel@xxxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 28 Aug 2007 22:10:32 +0200
Cc: Jambunathan K <jambunathan@xxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Sanjeev Jorapur <sanjeev@xxxxxxxxxx>
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In-reply-to: <C2F8BD7C.CFC8%Keir.Fraser@xxxxxxxxxxxx> (Keir Fraser's message of "Mon, 27 Aug 2007 17:42:20 +0100")
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Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> writes:

> On 27/8/07 17:34, "Jambunathan K" <jambunathan@xxxxxxxxxx> wrote:
>> I didn't create any dummy device whatsoever in case of Xen304 kernel for
>> fn1 to be reported in lspci. (Xen304 kernel was hand compiled from
>> vanilla sources as mentioned above)
>> You seem to suggest that behaviour in Xen304 was buggy and has been
>> addressed with Xen310.
>> I will try out the dummy device option and keep you posted.
> No, I think that the behaviour in the domU (scanning all fns) was different
> from native Linux behaviour in 3.0.4. This probably got fixed in 3.1.0 but
> that has broken export of just fn!=0 to pcifront. The possible fixes are:
>  1. Revert to scanning all fns in domU.
>  2. Modify pciback to supply a dummy device of some sort on fn==0, to stop
> the scan aborting.
> I'll have to look into this a bit. Option 1 is probably easier.

As I worte accidently direct to Keir and not to the list, I face the
same problem. I'd like to have option 1, because it worked fine and I
don't see a benefit of having a dummy device in the domU.

Dedecating single fnX to a domain is very usefull for example to give
the domUs ethernets of a four port card. I'm also running one domU
that is only using one of the USB 1.x controllers of a USB PCI addon


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