RFC: Using and renaming 8-bit reserved field of rte_crypto_op for implementation specific

["Kundapura, Ganapati" <ganapati.kundapura@intel.com>]

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Hi dpdk-dev,
   Can 'uint8_t reserved[1]' of 'struct rte_crypto_op' be renamed
to 'uint8_t impl_opaque' for implementation specific?

An implementation may use this field to hold implementation specific
value to share value between dequeue and enqueue operation and crypto library/driver
can also use this field to share implementation specfic value to event crypto adapter/application.

'struct rte_event' has 'uint8_t impl_opaque' member
struct rte_event {
                ...
                uint8_t impl_opaque;
                /**< Implementation specific opaque value.
                * An implementation may use this field to hold
                * implementation specific value to share between
                * dequeue and enqueue operation.
                * The application should not modify this field.
                */
                ...
};

Event crypto adapter, on dequeuing the event, enqueues rte_event::event_ptr
to cryptodev as rte_crypto_op and converts the dequeued crypto op to rte_event
without restoring the implementation specific opaque value.

By having the 'uint8_t impl_opaque' member in 'struct rte_crypto_op' as
diff --git a/lib/cryptodev/rte_crypto.h b/lib/cryptodev/rte_crypto.h
index dbc2700..af46ec9 100644
--- a/lib/cryptodev/rte_crypto.h
+++ b/lib/cryptodev/rte_crypto.h
@@ -146,10 +146,13 @@ struct rte_crypto_op {
                                /**< TLS record */
                        } param1;
                        /**< Additional per operation parameter 1. */
-                       uint8_t reserved[1];
-                       /**< Reserved bytes to fill 64 bits for
-                        * future additions
+                       uint8_t impl_opaque;
+                       /**< Implementation specific opaque value.
+                        * An implementation may use this field to hold
+                        * implementation specific value to share between
+                        * dequeue and enqueue operation.
                         */
+

which is untouched in library/driver and rte_event::impl_opaque field can be restored
while enqueuing the event back to eventdev.

Also crypto library/driver can use rte_crypto_op::impl_opaque field to
share implementation specific opaque value to the event crypto adapter/application.

I look forward to feedback on this proposal. Patch will be submitted
for review once the initial feedback is received.

Thank you,
Ganapati

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