mbuf: align layout in Windows

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@mellanox.com>
Tested-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
Acked-by: Ranjit Menon <ranjit.menon@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>

diff --git a/lib/librte_mbuf/rte_mbuf_core.h b/lib/librte_mbuf/rte_mbuf_core.h
index 22be41e..16600f1 100644 (file)
--- a/lib/librte_mbuf/rte_mbuf_core.h
+++ b/lib/librte_mbuf/rte_mbuf_core.h
@@ -523,11 +523,12 @@ 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;
@@ -543,7 +544,7 @@ struct rte_mbuf {
                                        /**< Inner L3 type. */
                                };
                        };
-                       uint32_t inner_l4_type:4; /**< Inner L4 type. */
+                       uint8_t inner_l4_type:4; /**< Inner L4 type. */
                };
        };