netdev - Re: [PATCH v7 net-next 4/4] netvsc: refactor notifier/event handling code to use the failover framework

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Message-ID: <20180424043042-mutt-send-email-mst@kernel.org>
Date:   Tue, 24 Apr 2018 04:42:22 +0300
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     Siwei Liu <loseweigh@...il.com>, Jiri Pirko <jiri@...nulli.us>,
        Sridhar Samudrala <sridhar.samudrala@...el.com>,
        David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org,
        virtio-dev@...ts.oasis-open.org,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        Alexander Duyck <alexander.h.duyck@...el.com>,
        Jakub Kicinski <kubakici@...pl>,
        Jason Wang <jasowang@...hat.com>
Subject: Re: [PATCH v7 net-next 4/4] netvsc: refactor notifier/event handling
 code to use the failover framework

On Mon, Apr 23, 2018 at 06:25:03PM -0700, Stephen Hemminger wrote:
> On Mon, 23 Apr 2018 12:44:39 -0700
> Siwei Liu <loseweigh@...il.com> wrote:
> 
> > On Mon, Apr 23, 2018 at 10:56 AM, Michael S. Tsirkin <mst@...hat.com> wrote:
> > > On Mon, Apr 23, 2018 at 10:44:40AM -0700, Stephen Hemminger wrote:  
> > >> On Mon, 23 Apr 2018 20:24:56 +0300
> > >> "Michael S. Tsirkin" <mst@...hat.com> wrote:
> > >>  
> > >> > On Mon, Apr 23, 2018 at 10:04:06AM -0700, Stephen Hemminger wrote:  
> > >> > > > >
> > >> > > > >I will NAK patches to change to common code for netvsc especially the
> > >> > > > >three device model.  MS worked hard with distro vendors to support transparent
> > >> > > > >mode, ans we really can't have a new model; or do backport.
> > >> > > > >
> > >> > > > >Plus, DPDK is now dependent on existing model.  
> > >> > > >
> > >> > > > Sorry, but nobody here cares about dpdk or other similar oddities.  
> > >> > >
> > >> > > The network device model is a userspace API, and DPDK is a userspace application.  
> > >> >
> > >> > It is userspace but are you sure dpdk is actually poking at netdevs?
> > >> > AFAIK it's normally banging device registers directly.
> > >> >  
> > >> > > You can't go breaking userspace even if you don't like the application.  
> > >> >
> > >> > Could you please explain how is the proposed patchset breaking
> > >> > userspace? Ignoring DPDK for now, I don't think it changes the userspace
> > >> > API at all.
> > >> >  
> > >>
> > >> The DPDK has a device driver vdev_netvsc which scans the Linux network devices
> > >> to look for Linux netvsc device and the paired VF device and setup the
> > >> DPDK environment.  This setup creates a DPDK failsafe (bondingish) instance
> > >> and sets up TAP support over the Linux netvsc device as well as the Mellanox
> > >> VF device.
> > >>
> > >> So it depends on existing 2 device model. You can't go to a 3 device model
> > >> or start hiding devices from userspace.  
> > >
> > > Okay so how does the existing patch break that? IIUC does not go to
> > > a 3 device model since netvsc calls failover_register directly.
> > >  
> > >> Also, I am working on associating netvsc and VF device based on serial number
> > >> rather than MAC address. The serial number is how Windows works now, and it makes
> > >> sense for Linux and Windows to use the same mechanism if possible.  
> > >
> > > Maybe we should support same for virtio ...
> > > Which serial do you mean? From vpd?
> > >
> > > I guess you will want to keep supporting MAC for old hypervisors?
> 
> The serial number has always been in the hypervisor since original support of SR-IOV
> in WS2008.  So no backward compatibility special cases would be needed.

Is that a serial from real hardware or a hypervisor thing?


-- 
MST