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Subject: Re: [net-next] seg6: add support for optional attributes during
 behavior construction
To:     David Miller <davem@davemloft.net>
Cc:     kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org,
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References: <20200319183641.29608-1-andrea.mayer@uniroma2.it>
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From:   Stefano Salsano <stefano.salsano@uniroma2.it>
Message-ID: <1a9409cd-0e2b-577b-f522-4149beca9d7c@uniroma2.it>
Date:   Tue, 31 Mar 2020 03:32:11 +0200
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Il 2020-03-31 02:49, David Miller ha scritto:
> From: Stefano Salsano <stefano.salsano@uniroma2.it>
> Date: Tue, 31 Mar 2020 01:23:48 +0200
> 
>> Of course a new application (e.g. iproute2, pyroute) using a new optional
>> parameter will not work on older kernels, but simply because the new parameter
>> is not supported. It will not work even without our proposed patch.
>>
>> On the other hand, we think that the solution in the patch is more backward
>> compatible. Without the patch, if we define new attributes, old applications
>> (e.g. iproute2 scripts) will not work on newer kernels, while with the optional
>> attributes approach proposed in the patch they will work with no issues !
> 
> Translation: You want to add backwards compatibility problems because
> otherwise you'll have to add backwards compatibility problems.

no this is not the correct translation :-) we do not want to add any 
backward compatility problem

we need to add a number of new parameters, if we keep the current 
approach these parameters will be mandatory and we will have backward 
compatibility problems: old applications will not work with new kernels

if we are allowed to add optional parameters, old applications and new 
applications will be able to work with old kernels and new kernels in 
any combination

> Sorry, I'm still not convinced.
> 
> You must find another way to achieve your objective.


-- 
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Stefano Salsano
Professore Associato
Dipartimento Ingegneria Elettronica
Universita' di Roma Tor Vergata
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