From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [virtio-dev] Re: [Qemu-devel] [PATCH] qemu: Introduce
 VIRTIO_NET_F_STANDBY feature bit to virtio_net
Date: Tue, 19 Jun 2018 23:32:06 +0300
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Cc: Siwei Liu <loseweigh@gmail.com>,
        "Samudrala, Sridhar" <sridhar.samudrala@intel.com>,
        Alexander Duyck <alexander.h.duyck@intel.com>,
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        virtualization@lists.linux-foundation.org, konrad.wilk@oracle.com,
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        Joao Martins <joao.m.martins@oracle.com>,
        Venu Busireddy <venu.busireddy@oracle.com>,
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To: Cornelia Huck <cohuck@redhat.com>
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On Tue, Jun 19, 2018 at 12:54:53PM +0200, Cornelia Huck wrote:
> Sorry about dragging mainframes into this, but this will only work for
> homogenous device coupling, not for heterogenous. Consider my vfio-pci
> + virtio-net-ccw example again: The guest cannot find out that the two
> belong together by checking some group ID, it has to either use the MAC
> or some needs-to-be-architectured property.
> 
> Alternatively, we could propose that mechanism as pci-only, which means
> we can rely on mechanisms that won't necessarily work on non-pci
> transports. (FWIW, I don't see a use case for using vfio-ccw to pass
> through a network card anytime in the near future, due to the nature of
> network cards currently in use on s390.)

That's what it boils down to, yes.  If there's need to have this for
non-pci devices, then we should put it in config space.
Cornelia, what do you think?

-- 
MST