Re: [dpdk-dev] [dpdk-techboard] DPDK ABI/API Stability

[Neil Horman <nhorman@tuxdriver.com>]

On Mon, Apr 08, 2019 at 10:04:21AM +0100, Ray Kinsella wrote:
> On 07/04/2019 10:48, Thomas Monjalon wrote:
> > 04/04/2019 16:07, Burakov, Anatoly:
> >> On 04-Apr-19 1:52 PM, Ray Kinsella wrote:
> >>> On 04/04/2019 11:54, Bruce Richardson wrote:
> >>>> On Thu, Apr 04, 2019 at 10:29:19AM +0100, Burakov, Anatoly wrote:
> >>>>> On 03-Apr-19 4:42 PM, Ray Kinsella wrote:
> [SNIP]
> >> So, if we are to cement our core API - we have to make a concrete effort 
> >> to specify what goes and what stays, if we want it to be maintainable. 
> >> The DPDK 1.0 specification, if you will :)
> > 
> > "DPDK 1.0 specification", that's a great project name :-)
> > 
> 
> Honestly - I would say that I am nervous of this.
> 
> The definition of a DPDK 1.0 specification as a gate to API stability,
> feels like a "great plan tomorrow" instead of a "good plan" today. I
> think that getting people to dedicate time to such a specification might
> prove problematic and I could see this effort being very time consuming.
> It might never get completed.
> 
> My preference would be to instead adopt a well-publicised community
> timeline for adopting more conservative API maintenance rules.
> 
> Perhaps we could give ourselves as a community a time-limited window in
> which to address concerns around the API before they become hardened -
> perhaps say until DPDK 19.11 LTS, or something of the order of 6 months
> to 9 months.
> 
> We then would know the timeline when niggles like exposure of internal
> structures and mbuf structure needed to be sorted by and could
> prioritize accordingly.
> 
> Ray K

I'm hesitant to say this, because I'm not usually a fan of throwing up
barricades to progress, but might some level of CI integration be useful here?

Part of the problem, as I've seen it (and I think you've noted previously in
this thread), is that ABI stability just hasn't been a priority, and not
something that developers look at when making changes, nor when reviewers review
patches.  When I wrote the early ABI checking tools for DPDK, while the reaction
was generally positive (I think), the results were informational, and treated as
such (something to take note of perhaps, but something that could be ignored if
there were more pressing issues).  Perhaps a concrete step might be to run the
ABI checker during a CI run on every commit, and block acceptance of a patch if
it modifies the ABI.  That would at least put a procedural break in ABI
modification without clear approval from the board.

Neil