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: <20180423205019-mutt-send-email-mst@kernel.org>
Date:   Mon, 23 Apr 2018 20:56:09 +0300
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     Jiri Pirko <jiri@...nulli.us>,
        Sridhar Samudrala <sridhar.samudrala@...el.com>,
        davem@...emloft.net, netdev@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        virtio-dev@...ts.oasis-open.org, jesse.brandeburg@...el.com,
        alexander.h.duyck@...el.com, kubakici@...pl, jasowang@...hat.com,
        loseweigh@...il.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 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?

It all seems like a reasonable thing to support in the generic core.

-- 
MST