18/05/2020 13:48, Ray Kinsella: > On 18/05/2020 11:46, Thomas Monjalon wrote: > > 18/05/2020 11:30, Ray Kinsella: > >> On 18/05/2020 10:22, Thomas Monjalon wrote: > >>> 18/05/2020 08:29, Ray Kinsella: > >>>> On 17/05/2020 20:52, Dumitrescu, Cristian wrote: > >>>>> From: Yigit, Ferruh <ferruh.yi...@intel.com> > >>>>>> > >>>>>> On v20.02 some meter APIs have been matured and symbols moved from > >>>>>> EXPERIMENTAL to DPDK_20.0.1 block. > >>>>>> > >>>>>> This can break the applications that were using these mentioned APIs on > >>>>>> v19.11. Although there is no modification on the APIs and the action is > >>>>>> positive and matures the APIs, the affect can be negative to > >>>>>> applications. > >>>>>> > >>>>>> Since experimental APIs can change or go away without notice as part of > >>>>>> contract, to prevent this negative affect that may occur by maturing > >>>>>> experimental API, a process update already suggested, which enables > >>>>>> aliasing without forcing it: > >>>>>> https://patches.dpdk.org/patch/65863/ > >>>>>> > >>>>> > >>>>> Personally, I am not convinced this is really needed. > >>>>> > >>>>> Are there any users asking for this? > >>>> > >>>> As it happens it is all breaking our abi regression test suite. > >>>> One of the things we do is to run the unit tests binary from v19.11 > >>>> against the latest release. > >>>> > >>>>> Is there any other library where this is also applied, or is > >>>>> librte_meter the only library? > >>>> > >>>> librte_meter is the only example AFAIK. > >>>> But then we only have one example of needing symbol versioning also at > >>>> the moment (Cryptodev). > >>>> > >>>> This is going to happen with experimental symbols that have been around > >>>> a while, > >>>> that have become used in applications. It is a non-mandatory tool a > >>>> maintainer can use > >>>> to preserve abi compatibility. > >>> > >>> If you want to maintain ABI compatibility of experimental symbols, > >>> it IS a mandatory tool. > >>> You cannot enforce your "ABI regression test suite" and at the same time > >>> say it is "non-mandatory". > >>> > >>> The real question here is to know whether we want to maintain > >>> compatibility > >>> of experimental symbols. We said no. Then we said we can. > >>> The main concern is the message clarity in my opinion. > >>> > >> > >> There is complete clarity, there is no obligation. > >> Our lack of obligation around experimental, is upfront in the policy is > >> upfront in the policy. > >> > >> "Libraries or APIs marked as experimental may change without constraint, > >> as they are not considered part of an ABI version. Experimental libraries > >> have the major ABI version 0." > >> > >> Later we give the _option_ without obligation to add an alias to > >> experimental.pls see the v6. > >> > >> + - In situations in which an ``experimental`` symbol has been stable > >> for some > >> + time. When promoting the symbol to become part of the next ABI > >> version, the > >> + maintainer may choose to provide an alias to the ``experimental`` > >> tag, so > >> + as not to break consuming applications. > >> > >> So it is something a Maintainer, _may_ choose to do. > >> I use the word, "may" not "will" as there is no obligation's associated > >> with experimental. > > > > > > OK Ray, this is my understanding as well. > > > > The only difficult part to understand is when claiming > > "it is all breaking our abi regression test suite" > > to justify the choice. > > Justification, is the same as any other consumer of DPDK saying you broke my > APP. > > > As the maintainer (Cristian) says he does not like this change, > > it means the regression test suite should skip this case, right? > > So the regression test run the v19.11 Unit Test's against the v20.05 rc. > My thought was that would provide reasonably good coverage of the ABI to > catch more subtly regression. > Those regressions that affect the behavior of the ABI (the contract), instead > of ABI itself.
I understand the goal. And I think, because of this goal, you will try to maintain ABI compat of *ALL* experimental symbols maturing as stable symbol.
