From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Lunn <andrew@lunn.ch>
Subject: Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice
Date: Wed, 4 Apr 2018 22:08:28 +0200
Message-ID: <20180404200828.GA29717@lunn.ch>
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Cc: Siwei Liu <loseweigh@gmail.com>, Jiri Pirko <jiri@resnulli.us>,
        Si-Wei Liu <si-wei.liu@oracle.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Stephen Hemminger <stephen@networkplumber.org>,
        Alexander Duyck <alexander.h.duyck@intel.com>,
        David Miller <davem@davemloft.net>,
        "Brandeburg, Jesse" <jesse.brandeburg@intel.com>,
        Jakub Kicinski <kubakici@wp.pl>,
        Jason Wang <jasowang@redhat.com>,
        "Samudrala, Sridhar" <sridhar.samudrala@intel.com>,
        Netdev <netdev@vger.kernel.org>,
        virtualization@lists.linux-foundation.org
To: David Ahern <dsahern@gmail.com>
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> Networking vendors have out of tree kernel modules. Those modules use a
> netdev (call it a master netdev, a control netdev, cpu port, whatever)
> to pull packets from the ASIC and deliver to virtual netdevices
> representing physical ports.

Sounds a lot like DSA. Please ask the vendor to contribute the drivers
:-)

> The master netdev should not be mucked with by a user. It should be
> ignored by certain s/w with lldpd as just an *example*.

I have come across occasional problems with the master device in DSA.
But nothing too serious. Generally the switch will just toss frames it
gets which don't have the needed header, when they come direct from
the master device, rather than via the slave devices.

    Andrew