net/i40e: support ARM platform

And add read memory barrier to avoid status inconsistency
between two Rx descriptors readings.

Signed-off-by: Jianbo Liu <jianbo.liu@linaro.org>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>

config/defconfig_arm64-armv8a-linuxapp-gcc

@@ -45,6 +45,6 @@ CONFIG_RTE_TOOLCHAIN_GCC=y
 CONFIG_RTE_EAL_IGB_UIO=n
 
 CONFIG_RTE_LIBRTE_FM10K_PMD=n
-CONFIG_RTE_LIBRTE_I40E_PMD=n
+CONFIG_RTE_LIBRTE_I40E_INC_VECTOR=n
 
 CONFIG_RTE_SCHED_VECTOR=n

doc/guides/nics/features/i40e.ini

@@ -45,3 +45,4 @@ Linux UIO            = Y
 Linux VFIO           = Y
 x86-32               = Y
 x86-64               = Y
+ARMv8                = Y

drivers/net/i40e/i40e_rxtx.c

@@ -994,6 +994,8 @@ i40e_rx_scan_hw_ring(struct i40e_rx_queue *rxq)
 					I40E_RXD_QW1_STATUS_SHIFT;
 		}
 
+		rte_smp_rmb();
+
 		/* Compute how many status bits were set */
 		for (j = 0, nb_dd = 0; j < I40E_LOOK_AHEAD; j++)
 			nb_dd += s[j] & (1 << I40E_RX_DESC_STATUS_DD_SHIFT);