[dpdk-dev] [PATCH] mbuf: align rte_mbuf for Windows

[talshn at mellanox.com]

From: Tal Shnaiderman <talshn at mellanox.com>

Using uint32_t type bit-fields in Windows will pads the
'L2/L3/L4 and tunnel information' union with additional bits.

This padding causes rte_mbuf size misalignment and the total size
increases to 3 cache-lines.

Changed packet_type bit-fields types from uint32_t to uint8_t
to allow unified 2 cache-line structure size.

Added the __extension__ attribute over the modified struct to avoid
the warning:

type of bit-field ... is a GCC extension [-pedantic]

Signed-off-by: Tal Shnaiderman <talshn at mellanox.com>
---
 lib/librte_mbuf/rte_mbuf_core.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/lib/librte_mbuf/rte_mbuf_core.h b/lib/librte_mbuf/rte_mbuf_core.h
index b9a59c879..82441555e 100644
--- a/lib/librte_mbuf/rte_mbuf_core.h
+++ b/lib/librte_mbuf/rte_mbuf_core.h
@@ -521,11 +521,12 @@ struct rte_mbuf {
 	RTE_STD_C11
 	union {
 		uint32_t packet_type; /**< L2/L3/L4 and tunnel information. */
+		__extension__
 		struct {
-			uint32_t l2_type:4; /**< (Outer) L2 type. */
-			uint32_t l3_type:4; /**< (Outer) L3 type. */
-			uint32_t l4_type:4; /**< (Outer) L4 type. */
-			uint32_t tun_type:4; /**< Tunnel type. */
+			uint8_t l2_type:4; /**< (Outer) L2 type. */
+			uint8_t l3_type:4; /**< (Outer) L3 type. */
+			uint8_t l4_type:4; /**< (Outer) L4 type. */
+			uint8_t tun_type:4; /**< Tunnel type. */
 			RTE_STD_C11
 			union {
 				uint8_t inner_esp_next_proto;
@@ -541,7 +542,7 @@ struct rte_mbuf {
 					/**< Inner L3 type. */
 				};
 			};
-			uint32_t inner_l4_type:4; /**< Inner L4 type. */
+			uint8_t inner_l4_type:4; /**< Inner L4 type. */
 		};
 	};
 
-- 
2.16.1.windows.4