doc: add deprecation notice for external memory

Due to the upcoming external memory support [1], some API and ABI
changes will be required. In addition, although the changes called
out in the deprecation notice are not yet present in form of code
in the published RFC itself, they are based on consensus on the
mailing list [2] on how to best implement this feature.

[1] http://patches.dpdk.org/project/dpdk/list/?series=453&state=*
[2] https://mails.dpdk.org/archives/dev/2018-July/108002.html

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Keith Wiles <keith.wiles@intel.com>
Acked-by: Zhihong Wang <zhihong.wang@intel.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Acked-by: Yongseok Koh <yskoh@mellanox.com>
Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Shreyansh Jain <shreyansh.jain@nxp.com>

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 87be8d6..bade1e4 100644 (file)
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -8,6 +8,21 @@ API and ABI deprecation notices are to be posted here.
 Deprecation Notices
 -------------------
 
+* eal: certain structures will change in EAL on account of upcoming external
+  memory support. Aside from internal changes leading to an ABI break, the
+  following externally visible changes will also be implemented:
+
+  - ``rte_memseg_list`` will change to include a boolean flag indicating
+    whether a particular memseg list is externally allocated. This will have
+    implications for any users of memseg-walk-related functions, as they will
+    now have to skip externally allocated segments in most cases if the intent
+    is to only iterate over internal DPDK memory.
+  - ``socket_id`` parameter across the entire DPDK will gain additional meaning,
+    as some socket ID's will now be representing externally allocated memory. No
+    changes will be required for existing code as backwards compatibility will
+    be kept, and those who do not use this feature will not see these extra
+    socket ID's.
+
 * eal: both declaring and identifying devices will be streamlined in v18.08.
   New functions will appear to query a specific port from buses, classes of
   device and device drivers. Device declaration will be made coherent with the