Re: [dpdk-dev] [PATCH] ethdev: deprecate shared counters using action attribute

[Thomas Monjalon <thomas@monjalon.net>]

+Cc techboard

There is an interesting case here that we should decide
how to manage in general. Please see below.

01/11/2020 08:49, Ori Kam:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 29/10/2020 15:39, Ori Kam:
> > > >  struct rte_flow_action_count {
> > > > -	uint32_t shared:1; /**< Share counter ID with other flow rules. */
> > > > +	/** @deprecated Share counter ID with other flow rules. */
> > > > +	uint32_t shared:1;
> > > >  	uint32_t reserved:31; /**< Reserved, must be zero. */
> > > >  	uint32_t id; /**< Counter ID. */
> > > >  };
> > >
> > > As much as I agree with your patch, I don't think we should push it since
> > > not all PMD made the move to support count action, so the application still
> > needs
> > > to use this API.
> > >
> > > I think this patch should be done but in next LTS release.
> > 
> > The patch is not removing the field,
> > it is just warning it will be removed in next year.
> 
> Yes I know, but I don't think it is correct to issue such a warning without support.
> The application still must use this API, the warning should be added as soon as
> at least one PMD support shared counters with the new API.

It should be replaced with shared actions API,
but you claim it is not supported yet. Right?
What are the criterias to define the replacement as supported?

What to do in such case?
Can we warn about a deprecation without having a proper replacement?
What is the pre-condition to warn about a deprecation?

About the complete removal, it has already been decided by the techboard
that we cannot remove an API until its replacement is stable.
In other words, the new experimental API must be promoted
in the stable ABI, before removing the deprecated API.