Re: [PATCH 1/4 net-next] net: phy: add Generic Netlink Ethernet switch configuration API

[Maxime Bizon <mbizon@freebox.fr>]

On Wed, 2013-10-30 at 07:50 -0400, Jamal Hadi Salim wrote:

> The important part is all the APIs stay consistent. I can use
> same netlink calls. ifconfig works.
> iproute2 works. People have written books on this stuff - we dont

these books usually start by telling people to assign IP address to
interfaces, not applicable here.

> If i can get stats by doing ifconfig - that should provide illusion that
> the netdevice is sending/receiving packets.

4 separated netdevices looks like 4 ethernet segments to me, and nothing
will prevent me from setting a different ip network on each device.

ENOTSUPP cannot be returned by ndo_start_xmit, the ability for a
netdevice to be able to receive/send packet from host is IMO
fundamental.

> This is a good arguement.
> Can we hear a little more about this?

see this kind of old threads:

http://rt2x00.serialmonkey.com/phpBB/viewtopic.php?f=5&t=4378
http://www.linuxquestions.org/questions/linux-networking-3/what-is-wmaster0-728708/
http://forums.debian.net/viewtopic.php?p=219440

> I think that would be a reasonable thing to do if it becomes
> necessary.

with rough naming:

- struct netdevice
- struct netdev_queue
- struct network_port (something to call ethtool on)
- struct bridge_dev (something you create/destroy vlan on, control FDB)
- struct bridge_port (something you set path cost on, ...)
- struct sw_bridge_dev (netdevice + underlying bridge_dev)
- struct sw_bridge_port (netdevice + underlying bridge_port)

old netdevice => (netdevice + netdev_queue * x + network_port)

ethtool works on netdevice or network_port

brctl addbr/addif creates sw_bridge_dev/sw_bridge_port, other commands
work on bridge_dev/bridge_port

drivers can register bridge_dev / bridge_port / network_port

simple case of a system with single ethernet mac & directly attached 4
ports switch:

netdevice: eth0
bridge_dev: hwbr0
bridge_port: hwbr0p0, hwbr0p1, hwbr0p2, hwbr0p3
network ports: eth0np0, hwbr0np0, hwbr0np1, hwbr0np2, hwbr0np3

ifconfig, ip link show only eth0
brctl show hwbr0
ethtool works on eth0 or eth0p0, hwbr0npX

-- 
Maxime