ethdev: comment statistics field support

Add comments to describe that not all statistics fields in
struct rte_eth_stats are supported by any type of network
interface card. If any statistics field is not supported,
its value is 0.

Signed-off-by: Wei Dai <wei.dai@intel.com>

diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
index 38641e8..9678179 100644 (file)
--- a/lib/librte_ether/rte_ethdev.h
+++ b/lib/librte_ether/rte_ethdev.h
@@ -190,6 +190,9 @@ struct rte_mbuf;
 
 /**
  * A structure used to retrieve statistics for an Ethernet port.
+ * Not all statistics fields in struct rte_eth_stats are supported
+ * by any type of network interface card (NIC). If any statistics
+ * field is not supported, its value is 0.
  */
 struct rte_eth_stats {
        uint64_t ipackets;  /**< Total number of successfully received packets. */