Re: [dpdk-dev] [PATCH v3 5/6] doc: remove dpdk iova aware notice

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Oct 25, 2017 at 12:12:57PM +0200, Thomas Monjalon wrote:
> 25/10/2017 12:05, Bruce Richardson:
> > On Wed, Oct 25, 2017 at 12:01:26PM +0200, Thomas Monjalon wrote:
> > > 25/10/2017 11:50, Richardson, Bruce:
> > > > From: Thomas Monjalon
> > > > > > On Tuesday 24 October 2017 01:59 AM, Thomas Monjalon wrote:
> > > > > > > 20/10/2017 14:31, Santosh Shukla:
> > > > > > >> Removed dpdk iova aware ABI deprecation notice, and updated ABI
> > > > > > >> change details in release_17.11.rst.
> > > > > > >>
> > > > > > >> Signed-off-by: Santosh Shukla <santosh.shukla@caviumnetworks.com>
> > > > > > >> Acked-by: John McNamara <john.mcnamara@intel.com>
> > > > > > >> ---
> > > > > > >> --- a/doc/guides/rel_notes/deprecation.rst
> > > > > > >> +++ b/doc/guides/rel_notes/deprecation.rst
> > > > > > >> -* eal: An ABI change is planned for 17.11 to make DPDK aware of
> > > > > > >> IOVA address
> > > > > > >> -  translation scheme.
> > > > > > >> -  Reference to phys address in EAL data-structure or functions may
> > > > > > >> change to
> > > > > > >> -  IOVA address or more appropriate name.
> > > > > > >> -  The change will be only for the name.
> > > > > > >> -  Functional aspects of the API or data-structure will remain same.
> > > > > > > Sorry, this series cannot be applied as is because it is breaking
> > > > > > > more than EAL API. The API of mbuf and mempool are also changed.
> > > > > > > We need to choose one of these three options:
> > > > > > > 	1/ accept to break all API in 17.11
> > > > > > > 	2/ postpone the whole series to 18.02
> > > > > >
> > > > > > Theme of series is to make dpdk iova aware so I would prefer option 1)
> > > > > or 2).
> > > > > > However I have no strong opinion on this topic.
> > > > > > Lets get more opinion from others about option 1/2/3.
> > > > > >
> > > > > > > 	3/ rename only EAL API in 17.11 and postpone mbuf/mempool
> > > > > 
> > > > > After discussing with Olivier it appeared there is a fourth solution.
> > > > > We should not break any API (EAL, mbuf, mempool).
> > > > > 
> > > > > I would like to merge these changes in RC2, but keeping compatibility with
> > > > > old names:
> > > > > - When you rename a function or a type, you can define a macro for the old
> > > > > name, alias the new name.
> > > > 
> > > > Note: using a macro doesn't prevent the ABI being broken if you rename a public function. You'll need to use function versioning too.
> > > 
> > > True
> > > We can use an inline function to avoid ABI breakage.
> > 
> > Nope, inline function won't work either, since that ends up the same as
> > the macro and compiled into the end app, not the library ABI. You
> > need a public non-inline wrapper function to keep ABI, or else function
> > renaming via symbol versioning/mapping.
> 
> Ah ah ah, I'm writing before thinking :)
> Yes, the function must not be inlined.
> 
> And generally speaking it is not an issue,
> even for performance critical functions.
> Adding one more function call in the path is not a bad thing
> for deprecated functions.
> I've seen another project (don't remember which one) adding a
> sleep() in deprecated functions and increasing the sleep time
> at each new release :)

Genius!!