Re: [dpdk-dev] [dpdk-dev v2 1/2] ethdev: add new tunnel type for ecpri

[Thomas Monjalon <thomas@monjalon.net>]

08/01/2021 15:07, Kinsella, Ray:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 08/01/2021 11:43, Ferruh Yigit:
> > > On 1/8/2021 10:23 AM, Thomas Monjalon wrote:
> > > > 08/01/2021 10:22, Ferruh Yigit:
> > > >> On 1/7/2021 1:33 PM, Thomas Monjalon wrote:
> > > >>> 07/01/2021 13:47, Zhang, Qi Z:
> > > >>>> From: Thomas Monjalon <thomas@monjalon.net>
> > > >>>>> 07/01/2021 10:32, Guo, Jia:
> > > >>>>>> From: Thomas Monjalon <thomas@monjalon.net>
> > > >>>>>>> Sorry, it is a nack.
> > > >>>>>>> BTW, it is probably breaking the ABI because of
> > RTE_TUNNEL_TYPE_MAX.
> > > >>>>
> > > >>>> Yes that may break the ABI but fortunately the checking-abi-
> > compatibility tool shows negative :) , thanks Ferruh' s guide.
> > > >>>> https://github.com/ferruhy/dpdk/actions/runs/468859673
> > > >>>
> > > >>> That's very strange. An enum value is changed.
> > > >>> Why it is not flagged by libabigail?
> > > >>
> > > >> As long as the enum values not sent to the application and kept
> > > >> within the library, changing their values shouldn't be problem.
> > > >
> > > > But RTE_TUNNEL_TYPE_MAX is part of lib/librte_ethdev/rte_ethdev.h
> > so
> > > > it is exposed to the application.
> > > > I think it is a case of ABI breakage.
> > >
> > > Yes it is exposed to the application. But in runtime does it
> > exchanged
> > > between library and application is the issue I think.
> > > For this case it seems it is not, so not an ABI break.
> > 
> > If I create a table of size RTE_TUNNEL_TYPE_MAX with DPDK 20.11, I will
> > get an overflow when writing to the new ECPRI index.
> 
> I guess the question is - are you likely to do this?

As said below, no I cannot think about such a case myself.

> > The question is: can I receive the ECPRI value dynamically from ethdev?
> > If yes, it is an ABI breakage. But I cannot think of such case now.