[dpdk-dev] [PATCH v2] doc: announce ABI change for mbuf structure

[Ferruh Yigit]

On 7/20/2016 8:16 AM, Olivier Matz wrote:
> For 16.11, the mbuf structure will be modified implying ABI breakage.
> Some discussions already took place here:
> http://www.dpdk.org/dev/patchwork/patch/12878/
> 
> Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
> ---
> 
> v1->v2:
> - reword the sentences to keep things more open, as suggested by Bruce
> 
>  doc/guides/rel_notes/deprecation.rst | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> index f502f86..b9f5a93 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -41,3 +41,9 @@ Deprecation Notices
>  * The mempool functions for single/multi producer/consumer are deprecated and
>    will be removed in 16.11.
>    It is replaced by rte_mempool_generic_get/put functions.
> +
> +* ABI changes are planned for 16.11 in the ``rte_mbuf`` structure: some fields
> +  may be reordered to facilitate the writing of ``data_off``, ``refcnt``, and
> +  ``nb_segs`` in one operation, because some platforms have an overhead if the
> +  store address is not naturally aligned. Other mbuf fields, such as the
> +  ``port`` field, may be moved or removed as part of this mbuf work.
> 

Not directly related to this patch, but generally for deprecation
notices, does it make sense to tag explicitly which library effected, like:

* librte_mbuf [perhaps with version here]:
  Explanation about deprecation ...

For this case it is more clear which library effected, but sometimes
that is not obvious from deprecation notice.

Also when checked for if specific library effected, it is harder to find
with current notes.

Thanks,
ferruh