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

[Thomas Monjalon <thomas@monjalon.net>]

25/11/2021 13:31, Ferruh Yigit:
> On 11/24/2021 3:37 PM, Viacheslav Ovsiienko wrote:
> > diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> > index 6d087c64ef..d04a606b7d 100644
> > --- a/doc/guides/rel_notes/deprecation.rst
> > +++ b/doc/guides/rel_notes/deprecation.rst
> > @@ -101,6 +101,20 @@ Deprecation Notices
> >     is deprecated as ambiguous with respect to the embedded switch. The use of
> >     these attributes will become invalid starting from DPDK 22.11.
> >   
> > +* ethdev: Actions ``OF_SET_MPLS_TTL``, ``OF_DEC_MPLS_TTL``, ``OF_SET_NW_TTL``,
> > +  ``OF_COPY_TTL_OUT``, ``OF_COPY_TTL_IN`` are deprecated as not supported by
> > +  PMDs, will be removed in DPDK 22.11.
> > +
> > +* ethdev: Actions ``OF_DEC_NW_TTL``, ``SET_IPV4_SRC``, ``SET_IPV4_DST``,
> > +  ``SET_IPV6_SRC``, ``SET_IPV6_DST``, ``SET_TP_SRC``, ``SET_TP_DST``,
> > +  ``DEC_TTL``, ``SET_TTL``, ``SET_MAC_SRC``, ``SET_MAC_DST``, ``INC_TCP_SEQ``,
> > +  ``DEC_TCP_SEQ``, ``INC_TCP_ACK``, ``DEC_TCP_ACK``, ``SET_IPV4_DSCP``,
> > +  ``SET_IPV6_DSCP``, ``SET_TAG``, ``SET_META`` are deprecated as superseded
> > +  by generic MODIFY_FIELD action, will be removed in DPDK 22.11.
> > +
> > +* ethdev: Actions ``OF_SET_VLAN_VID``, ``OF_SET_VLAN_PCP`` are deprecated
> > +  as superseded by generic MODIFY_FIELD action.
> > +
> 
> 
> I have a question about ABI/API related issue for rte_flow support,
> 
> If a driver removes an flow API item/action support, it directly impacts
> the user application. The application previously working may stop working
> and require code update, this is something we want to prevent with
> ABI policy. And this kind of changes are not caught by our tools.
> 
> Do we have a process to deprecate/remove a flow API item/action support?
> Like they can be only removed on ABI break release...

If possible, we should avoid removing them, or dropping support in a driver.
I think removing a feature could be considered only if not too many drivers
use it, or if it becomes a real burden to maintain.