[dpdk-dev] [PATCH v1 1/3] cryptodev: add min headroom and tailroom requirement

[Anoob Joseph <anoob.joseph@caviumnetworks.com>]

Enabling crypto devs to specify the minimum headroom and tailroom it
expects in the mbuf. For net PMDs, standard headroom has to be honoured
by applications, which is not strictly followed for crypto devs. This
prevents crypto devs from using free space in mbuf (available as
head/tailroom) for internal requirements in crypto operations. Addition
of head/tailroom requirement will help PMDs to communicate such
requirements to the application.

The availability and use of head/tailroom is an optimization if the
hardware supports use of head/tailroom for crypto-op info. For devices
that do not support using the head/tailroom, they can continue to operate
without any performance-drop.

Signed-off-by: Anoob Joseph <anoob.joseph@caviumnetworks.com>
---
v1:
* Removed deprecation notice
* Updated release note
* Renamed new fields to have 'mbuf' in the name
* Changed the type of new fields to uint16_t (instead of uint32_t)

 doc/guides/rel_notes/release_18_08.rst | 6 ++++++
 lib/librte_cryptodev/rte_cryptodev.h   | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/doc/guides/rel_notes/release_18_08.rst b/doc/guides/rel_notes/release_18_08.rst
index 5bc23c5..fae0d26 100644
--- a/doc/guides/rel_notes/release_18_08.rst
+++ b/doc/guides/rel_notes/release_18_08.rst
@@ -70,6 +70,12 @@ ABI Changes
    Also, make sure to start the actual text at the margin.
    =========================================================
 
+* cryptodev: Additional fields in rte_cryptodev_info.
+
+  Two new fields of type ``uint16_t`` added in ``rte_cryptodev_info``
+  structure: ``min_mbuf_headroom_req`` and ``min_mbuf_tailroom_req``. These
+  parameters specify the recommended headroom and tailroom for mbufs to be
+  processed by the PMD.
 
 Removed Items
 -------------
diff --git a/lib/librte_cryptodev/rte_cryptodev.h b/lib/librte_cryptodev/rte_cryptodev.h
index 92ce6d4..4e5b5b4 100644
--- a/lib/librte_cryptodev/rte_cryptodev.h
+++ b/lib/librte_cryptodev/rte_cryptodev.h
@@ -382,6 +382,12 @@ struct rte_cryptodev_info {
 	unsigned max_nb_queue_pairs;
 	/**< Maximum number of queues pairs supported by device. */
 
+	uint16_t min_mbuf_headroom_req;
+	/**< Minimum mbuf headroom required by device */
+
+	uint16_t min_mbuf_tailroom_req;
+	/**< Minimum mbuf tailroom required by device */
+
 	struct {
 		unsigned max_nb_sessions;
 		/**< Maximum number of sessions supported by device. */
-- 
2.7.4