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

[Kinsella, Ray]

> -----Original Message-----
> From: Thomas Monjalon <thomas at monjalon.net>
> Sent: Friday 8 January 2021 14:06
> To: Guo, Jia <jia.guo at intel.com>; Zhang, Qi Z <qi.z.zhang at intel.com>;
> Yigit, Ferruh <ferruh.yigit at intel.com>
> Cc: Wu, Jingjing <jingjing.wu at intel.com>; Yang, Qiming
> <qiming.yang at intel.com>; Wang, Haiyue <haiyue.wang at intel.com>;
> dev at dpdk.org; andrew.rybchenko at oktetlabs.ru; orika at nvidia.com;
> getelson at nvidia.com; Dodji Seketeli <dodji at redhat.com>; Kinsella, Ray
> <ray.kinsella at intel.com>
> Subject: Re: [dpdk-dev] [dpdk-dev v2 1/2] ethdev: add new tunnel type
> for ecpri
> 
> 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 at monjalon.net>
> > >>>>> 07/01/2021 10:32, Guo, Jia:
> > >>>>>> From: Thomas Monjalon <thomas at 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?

> 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.

Ray K