Re: [RFC PATCH net-next 1/1] net: Support for switch port configuration

[Roopa Prabhu]

On 12/11/14, 8:56 AM, Jiri Pirko wrote:
> Thu, Dec 11, 2014 at 05:37:46PM CET, roopa@xxxxxxxxxxxxxxxxxxx wrote:
> > On 12/11/14, 3:01 AM, Jiri Pirko wrote:
> > > Thu, Dec 11, 2014 at 10:59:42AM CET, marco.varlese@xxxxxxxxx wrote:
> > > > > -----Original Message-----
> > > > > From: John Fastabend [mailto:john.fastabend@xxxxxxxxx]
> > > > > Sent: Wednesday, December 10, 2014 5:04 PM
> > > > > To: Jiri Pirko
> > > > > Cc: Varlese, Marco; netdev@xxxxxxxxxxxxxxx;
> > > > > stephen@xxxxxxxxxxxxxxxxxx; Fastabend, John R;
> > > > > roopa@xxxxxxxxxxxxxxxxxxx; sfeldma@xxxxxxxxx; linux-
> > > > > kernel@xxxxxxxxxxxxxxx
> > > > > Subject: Re: [RFC PATCH net-next 1/1] net: Support for switch port
> > > > > configuration
> > > > >
> > > > > On 12/10/2014 08:50 AM, Jiri Pirko wrote:
> > > > > > Wed, Dec 10, 2014 at 05:23:40PM CET, marco.varlese@xxxxxxxxx wrote:
> > > > > > > From: Marco Varlese <marco.varlese@xxxxxxxxx>
> > > > > > >
> > > > > > > Switch hardware offers a list of attributes that are configurable on
> > > > > > > a per port basis.
> > > > > > > This patch provides a mechanism to configure switch ports by adding
> > > > > > > an NDO for setting specific values to specific attributes.
> > > > > > > There will be a separate patch that extends iproute2 to call the new
> > > > > > > NDO.
> > > > > > What are these attributes? Can you give some examples. I'm asking
> > > > > > because there is a plan to pass generic attributes to switch ports
> > > > > > replacing current specific ndo_switch_port_stp_update. In this case,
> > > > > > bridge is setting that attribute.
> > > > > >
> > > > > > Is there need to set something directly from userspace or does it make
> > > > > > rather sense to use involved bridge/ovs/bond ? I think that both will
> > > > > > be needed.
> > > > > +1
> > > > >
> > > > > I think for many attributes it would be best to have both. The in kernel callers
> > > > > and netlink userspace can use the same driver ndo_ops.
> > > > >
> > > > > But then we don't _require_ any specific bridge/ovs/etc module. And we
> > > > > may have some attributes that are not specific to any existing software
> > > > > module. I'm guessing Marco has some examples of these.
> > > > >
> > > > > [...]
> > > > >
> > > > >
> > > > > --
> > > > > John Fastabend         Intel Corporation
> > > > We do have a need to configure the attributes directly from user-space and I have identified the tool to do that in iproute2.
> > > >
> > > > An example of attributes are:
> > > > * enabling/disabling of learning of source addresses on a given port (you can imagine the attribute called LEARNING for example);
> > > > * internal loopback control (i.e. LOOPBACK) which will control how the flow of traffic behaves from the switch fabric towards an egress port;
> > > > * flooding for broadcast/multicast/unicast type of packets (i.e. BFLOODING, MFLOODING, UFLOODING);
> > > >
> > > > Some attributes would be of the type enabled/disabled while other will allow specific values to allow the user to configure different behaviours of that feature on that particular port on that platform.
> > > >
> > > > One thing to mention - as John stated as well - there might be some attributes that are not specific to any software module but rather have to do with the actual hardware/platform to configure.
> > > >
> > > > I hope this clarifies some points.
> > > It does. Makes sense. We need to expose this attr set/get for both
> > > in-kernel and userspace use cases.
> > >
> > > Please adjust you patch for this. Also, as a second patch, it would be
> > > great if you can convert ndo_switch_port_stp_update to this new ndo.
> > Why are we exposing generic switch attribute get/set from userspace ?. We
> > already have specific attributes for learning/flooding which can be extended
> > further.
> Yes, but that is for PF_BRIDGE and bridge specific attributes. There
> might be another generic attrs, no?
I cant think of any. And plus, the whole point of switchdev l2 offloads 
was to map these to existing
bridge attributes. And we already have a match for some of the 
attributes that marco wants.

If there is a need for such attributes, i don't see why it is needed for 
switch devices only.
It is needed for any hw (nics etc). And, a precedence to this is to do 
it via ethtool.

Having said that, am sure we will find a need for this in the future. 
And having a netlink attribute always helps.

Today, it seems like these can be mapped to existing attributes that are 
settable via ndo_bridge_setlink/getlink.

> > And for in kernel api....i had a sample patch in my RFC series (Which i was
> > going to resubmit, until it was decided that we will use existing api around
> > ndo_bridge_setlink/ndo_bridge_getlink):
> > http://www.spinics.net/lists/netdev/msg305473.html
> Yes, this might become handy for other generic non-bridge attrs.
>
> > Thanks,
> > Roopa

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