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

[Jiri Pirko]

Thu, Dec 11, 2014 at 06:41:13PM CET, roopa@xxxxxxxxxxxxxxxxxxx wrote:
>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.

Fair enough.

>
>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.

Okay. That makes sense so far for bridge.

>
>>
>>>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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