doc: announce ethernet structures alignment changes

Tell users about upcoming changes to rte_ether_addr and
rte_ether_header.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index b1aa6a8..bbe8090 100644 (file)
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -61,6 +61,16 @@ Deprecation Notices
   structure would be made internal (or removed if all dependencies are cleared)
   in future releases.
 
   structure would be made internal (or removed if all dependencies are cleared)
   in future releases.
 

+* net: The Ethernet address and header definitions will change
+  attributes. The Ethernet address struct will no longer be marked as
+  packed since the packed attribute is meaningless on a byte
+  array. The Ethernet header will be marked as aligned on a 2-byte
+  boundary and will no longer have the packed attribute. This allows
+  for efficient access on CPU architectures where unaligned access is
+  expensive. These changes should not impact normal usage because drivers
+  naturally align the Ethernet header on receive and all known
+  encapsulations preserve the alignment of the header.
+

 * ethdev: the legacy filter API, including
   ``rte_eth_dev_filter_supported()``, ``rte_eth_dev_filter_ctrl()`` as well
   as filter types MACVLAN, ETHERTYPE, FLEXIBLE, SYN, NTUPLE, TUNNEL, FDIR,
 * ethdev: the legacy filter API, including
   ``rte_eth_dev_filter_supported()``, ``rte_eth_dev_filter_ctrl()`` as well
   as filter types MACVLAN, ETHERTYPE, FLEXIBLE, SYN, NTUPLE, TUNNEL, FDIR,