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.
