[PATCH V2 net-next 1/6] ethtool: add support to set/get tx copybreak buf size via ethtool

@@ -1521,6 +1521,30 @@ Kernel response contents:
   ``ETHTOOL_A_PHC_VCLOCKS_INDEX``       s32     PHC index array
   ====================================  ======  ==========================
 
+TUNABLE_SET
+===========
+
+Request contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_TX_COPYBREAK_BUF_SIZE``      u32     buf size for tx copybreak
+  =====================================  ======  ==========================
+
+Tx copybreak buf size is used for tx copybreak feature, the feature is used
+for small size packet or frag. It adds a queue based tx shared bounce buffer
+to memcpy the small packet when the len of xmitted skb is below tx_copybreak
+(value to distinguish small size and normal size), and reduce the overhead
+of dma map and unmap when IOMMU is on.
+
+TUNABLE_GET
+===========
+
+Kernel response contents:
+
+  ====================================  ======  ==========================
+  ``ETHTOOL_TX_COPYBREAK_BUF_SIZE``     u32     buf size for tx copybreak
+  ====================================  ======  ==========================
+
 Request translation
 ===================
 

@@ -231,6 +231,7 @@ enum tunable_id {
 	ETHTOOL_RX_COPYBREAK,
 	ETHTOOL_TX_COPYBREAK,
 	ETHTOOL_PFC_PREVENTION_TOUT, /* timeout in msecs */
+	ETHTOOL_TX_COPYBREAK_BUF_SIZE,
 	/*
 	 * Add your fresh new tunable attribute above and remember to update
 	 * tunable_strings[] in net/ethtool/common.c

@@ -89,6 +89,7 @@ tunable_strings[__ETHTOOL_TUNABLE_COUNT][ETH_GSTRING_LEN] = {
 	[ETHTOOL_RX_COPYBREAK]	= "rx-copybreak",
 	[ETHTOOL_TX_COPYBREAK]	= "tx-copybreak",
 	[ETHTOOL_PFC_PREVENTION_TOUT] = "pfc-prevention-tout",
+	[ETHTOOL_TX_COPYBREAK_BUF_SIZE] = "tx-copybreak-buf-size",
 };
 
 const char

@@ -2381,6 +2381,7 @@ static int ethtool_tunable_valid(const struct ethtool_tunable *tuna)
 	switch (tuna->id) {
 	case ETHTOOL_RX_COPYBREAK:
 	case ETHTOOL_TX_COPYBREAK:
+	case ETHTOOL_TX_COPYBREAK_BUF_SIZE:
 		if (tuna->len != sizeof(u32) ||
 		    tuna->type_id != ETHTOOL_TUNABLE_U32)
 			return -EINVAL;