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

[Roopa Prabhu <roopa@cumulusnetworks.com>]

On 12/11/14, 3:01 AM, Jiri Pirko wrote:
> Thu, Dec 11, 2014 at 10:59:42AM CET, marco.varlese@intel.com wrote:
>>> -----Original Message-----
>>> From: John Fastabend [mailto:john.fastabend@gmail.com]
>>> Sent: Wednesday, December 10, 2014 5:04 PM
>>> To: Jiri Pirko
>>> Cc: Varlese, Marco; netdev@vger.kernel.org;
>>> stephen@networkplumber.org; Fastabend, John R;
>>> roopa@cumulusnetworks.com; sfeldma@gmail.com; linux-
>>> kernel@vger.kernel.org
>>> 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@intel.com wrote:
>>>>> From: Marco Varlese <marco.varlese@intel.com>
>>>>>
>>>>> 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.
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

Thanks,
Roopa