[dpdk-dev] [PATCH v3 7/7] abi: announce mbuf addition for ieee1588 in DPDK 2.2
Thomas Monjalon
thomas.monjalon at 6wind.com
Thu Jul 9 17:51:16 CEST 2015
2015-07-08 14:10, Bruce Richardson:
> On Mon, Jul 06, 2015 at 03:16:01PM +0200, Thomas Monjalon wrote:
> > 2015-07-02 16:16, John McNamara:
> > > --- a/doc/guides/rel_notes/abi.rst
> > > +++ b/doc/guides/rel_notes/abi.rst
> > > Deprecation Notices
> > > -------------------
> > > +
> > > +* In DPDK 2.1 the IEEE1588/802.1AS support in the i40e driver makes use of the
> > > + ``udata64`` field in the mbuf to pass the timesync register index to the
> > > + user. In DPDK 2.2 this will be moved to a new field in the mbuf.
> >
> > We need more acknowledgements for this decision, as stated here:
> > http://dpdk.org/browse/dpdk/tree/doc/guides/guidelines/versioning.rst#n51
>
> Why can't this new field just be added at the end of cache line 1 (the second
> cache line) of the mbuf? That would avoid any ABI breakage and would mean we
> can just put the change in in this release, instead of waiting.
Are you sure that (because of __rte_cache_aligned) the size of the structure
is never increased with this new field?
Please confirm your opinion.
A comment to explain ABI compatibility in the commit message of the v4 is
also welcome.
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