From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39965) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fVdqE-0001BY-CA for qemu-devel@nongnu.org; Wed, 20 Jun 2018 10:12:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fVdq8-0006wH-1G for qemu-devel@nongnu.org; Wed, 20 Jun 2018 10:12:10 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:41088 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fVdq7-0006wB-Rq for qemu-devel@nongnu.org; Wed, 20 Jun 2018 10:12:03 -0400 Date: Wed, 20 Jun 2018 17:11:59 +0300 From: "Michael S. Tsirkin" Message-ID: <20180620170904-mutt-send-email-mst@kernel.org> References: <20180612142557-mutt-send-email-mst@kernel.org> <20180614120231.0a72bd5f.cohuck@redhat.com> <20180615134815.6613620e.cohuck@redhat.com> <20180619125453.2d2dfb2d.cohuck@redhat.com> <20180619233001-mutt-send-email-mst@kernel.org> <20180620115359.1a3bf6fb.cohuck@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180620115359.1a3bf6fb.cohuck@redhat.com> Subject: Re: [Qemu-devel] [virtio-dev] Re: [PATCH] qemu: Introduce VIRTIO_NET_F_STANDBY feature bit to virtio_net List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck Cc: Siwei Liu , "Samudrala, Sridhar" , Alexander Duyck , virtio-dev@lists.oasis-open.org, aaron.f.brown@intel.com, Jiri Pirko , Jakub Kicinski , Netdev , qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, Joao Martins , Venu Busireddy , vijay.balakrishna@oracle.com On Wed, Jun 20, 2018 at 11:53:59AM +0200, Cornelia Huck wrote: > On Tue, 19 Jun 2018 23:32:06 +0300 > "Michael S. Tsirkin" wrote: > > > 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? > > > > I think the only really useful config on s390 is the vfio-pci network > card coupled with a virtio-net-ccw device: Using an s390 network card > via vfio-ccw is out due to the nature of the s390 network cards, and > virtio-ccw is the default transport (virtio-pci is not supported on any > enterprise distro AFAIK). > > For this, having a uuid in the config space could work (vfio-pci > devices have a config space by virtue of being pci devices, and > virtio-net-ccw devices have a config space by virtue of being virtio > devices -- ccw devices usually don't have that concept). OK so this calls for adding such a field generally (it's device agnostic right now). How would you suggest doing that? -- MST