RE: [PATCH v3] ethdev: deprecate header fields and metadata flow actions

[Ori Kam <orika@nvidia.com>]

Hi

> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Wednesday, November 24, 2021 7:33 PM
> 
> 24/11/2021 17:37, Slava Ovsiienko:
> > From: Ori Kam <orika@nvidia.com>
> > > From: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
> > > >  Action: ``OF_SET_MPLS_TTL``
> > > >  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > > +This action is deprecated. Consider `Action: MODIFY_FIELD`_.
> > > >
> > >
> > > Since no PMD support this action why set reference to MODIFY_FIELD_?
> > > Same for all unsupported actions.
> >
> > There are some references to this action in PMDs (for example bnxt),
> > but the ENOTSUP returned. I.e., action is in source code, but actually
> > not supported. Hence (due to this and in general), we can't just occasionally
> > remove existing actions, we should deprecate these first.
> > Other point - if someone will decide to implement support for this
> > action in his/her PMD - the deprecation notice will point out the right way -
> > "consider MODIFY_FIELD."
> >
If someone will want to create such action he can see how all the rest of the actions are done.
I don't think we need to point a user incorrect path.

> > >
> > > >  Implements ``OFPAT_SET_MPLS_TTL`` ("MPLS TTL") as defined by the
> > > > `OpenFlow  Switch Specification`_.
> > > > @@ -2254,6 +2255,7 @@ Switch Specification`_.
> > > >
> > [..snip..]
> > >
> > > If no PMD support this why do we want to add it to the modify_field?
> > > Same for all of the unsupported actions.
> > As I said above - we just propose to consider MODIFY_FIELD actions
> > if someone has intention to implement deprecated OFPAT_SET_MPLS_TTL.
> 
> It was an API, we must guide the API reader in the right direction.
> BTW, it can be implemented in a driver which is not yet upstream.
> 

So you think we should keep it?
The guideline is that if there is no implementation it should not go in.
I see that this API was added in 2018
if someone is using this API let him rise his voice.