[dpdk-dev] [PATCH 0/4] Add DSO symbol versioning to support backwards compatibility
Neil Horman
nhorman at tuxdriver.com
Wed Oct 1 20:59:40 CEST 2014
On Fri, Sep 26, 2014 at 10:45:49AM -0400, Neil Horman wrote:
> On Fri, Sep 26, 2014 at 12:41:33PM +0200, Thomas Monjalon wrote:
> > Hi Neil,
> >
> > 2014-09-24 14:19, Neil Horman:
> > > Ping Thomas. I know you're busy, but I would like this to not fall off anyones
> > > radar. You alluded to concerns regarding what, for lack of a better term,
> > > ABI/API lockin. I had asked you to enuumerate/elaborate on specifics, but never
> > > heard back. Are there further specifics you wish to discuss, or are you
> > > satisfied with the above answers?
> >
> > Sorry for not being very reactive on this thread.
> > All this discussion is very interesting but it's really not the proper
> > time to apply it. As you said, it requires an extra effort. I'm not saying
> > it will never be integrated. I'm just saying that we cannot change
> > everything at the same time.
> >
> > Let me sum up the situation. This community project has been very active
> > for few months now. First, we learnt how to make some releases together
> > and we are improving the process to be able to deliver a new major release
> > every 4 months while having some good quality process.
> > But these releases are still not complete because documentation is not
> > integrated yet. Then developers should have a role in documentation updates.
> > We also need to integrate and learn how to use more tools to be more
> > efficient and improve quality.
> >
> > So the question is "when should we care about API compatibility"?
> > And the answer is: ASAP, but not now. I feel next year is a better target.
> > Because the most important priority is to move together at a pace which
> > allow most of us to stay in the race.
> >
>
>
> I'm sorry Thomas, I don't accept this. I asked you for details as to your
> concerns regarding this patch series, and you've provided more vague comments.
> I need details to address
>
> You say it requires extra effort, you're right it does. Any feature that you
> integreate requires some additional effort. How is this patch any different
> from adding the acl library or any other new API? Everything requires
> maintenence, thats how software works. What specfically about this patch series
> makes the effort insurmountable to you?
>
> You say you're improving your process. Great, this patch aids in that process
> by ensuring backwards compatibility for a period of time. Given that the API
> and ABI can still evolve within this framework, as I've described, how is this
> patch series not a significant step forward toward your goal of quality process.
>
> You say documentation isn't integrated. So, what does getting documentation
> integrated have to do with this patch set, or any other? I don't see you
> holding any other patches based on documentation. Again, nothing in this series
> prevents evolution of the API or ABI. If you're hope is to wait until
> everything is perfect, then apply some control to the public facing API, and get
> it all documented, none of thosse things will ever happen, I promise you.
>
> You say you also need to learn to use more tools to be more efficient and
> improve quality. Great! Thats exactly what this is. If we mandate even a short
> term commitment to ABI stability (1 single relese worth of time), we will
> quickly identify what API's change quickly and where we need to be cautious with
> our API design. If you just assume that developers will get better of their own
> volition, it will never happen.
>
> You say this should go in next year, but not now. When exactly? What event do
> you forsee occuring in the next 12-18 months that will change everything such
> that we can start supporing an ABI for more than just a few weeks at the head of
> the tree?
>
> To this end, I just did a quick search through the git history for dpdk to look
> at the histories of all the header files that are exposed via the makefile
> SYMLINK command (given that that provides a list of header files that
> applications can include, and embodies all the function symbols and data types
> applications have access to.
>
> There are 179 total commits in that list
> Of those, a bit of spot checking suggests that about 10-15% of them actually
> change ABI, and many of those came from Bruce's rework of the mbuf structure.
> That about 17-20 instances over the last 2 years where an ABI update would have
> been needed. That seems pretty reasonable to me. Where exactly is your concern
> here?
>
> Neil
>
Ping Thomas, I'd like to continue this debate to a conclusion. Could you please
provide specific details and/or concerns that you have with this patch series?
Thanks
Neil
> > --
> > Thomas
> >
>
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