HAOKANG MU /

  • netdev_features_t
///include/linux/netdev_features.h

typedef u64 netdev_features_t;

enum {
	NETIF_F_SG_BIT,			/* Scatter/gather IO. */
	NETIF_F_IP_CSUM_BIT,		/* Can checksum TCP/UDP over IPv4. */
	__UNUSED_NETIF_F_1,
	NETIF_F_HW_CSUM_BIT,		/* Can checksum all the packets. */
	NETIF_F_IPV6_CSUM_BIT,		/* Can checksum TCP/UDP over IPV6 */
	NETIF_F_HIGHDMA_BIT,		/* Can DMA to high memory. */
	NETIF_F_FRAGLIST_BIT,		/* Scatter/gather IO. */
	NETIF_F_HW_VLAN_CTAG_TX_BIT,	/* Transmit VLAN CTAG HW acceleration */
	NETIF_F_HW_VLAN_CTAG_RX_BIT,	/* Receive VLAN CTAG HW acceleration */
	NETIF_F_HW_VLAN_CTAG_FILTER_BIT,/* Receive filtering on VLAN CTAGs */
	NETIF_F_VLAN_CHALLENGED_BIT,	/* Device cannot handle VLAN packets */
	NETIF_F_GSO_BIT,		/* Enable software GSO. */
	NETIF_F_LLTX_BIT,		/* LockLess TX - deprecated. Please */
					/* do not use LLTX in new drivers */
	NETIF_F_NETNS_LOCAL_BIT,	/* Does not change network namespaces */
	NETIF_F_GRO_BIT,		/* Generic receive offload */
	NETIF_F_LRO_BIT,		/* large receive offload */

	/**/NETIF_F_GSO_SHIFT,		/* keep the order of SKB_GSO_* bits */
	NETIF_F_TSO_BIT			/* ... TCPv4 segmentation */
		= NETIF_F_GSO_SHIFT,
	NETIF_F_UFO_BIT,		/* ... UDPv4 fragmentation */
	NETIF_F_GSO_ROBUST_BIT,		/* ... ->SKB_GSO_DODGY */
	NETIF_F_TSO_ECN_BIT,		/* ... TCP ECN support */
	NETIF_F_TSO6_BIT,		/* ... TCPv6 segmentation */
	NETIF_F_FSO_BIT,		/* ... FCoE segmentation */
	NETIF_F_GSO_GRE_BIT,		/* ... GRE with TSO */
	NETIF_F_GSO_UDP_TUNNEL_BIT,	/* ... UDP TUNNEL with TSO */
	/**/NETIF_F_GSO_LAST =		/* last bit, see GSO_MASK */
		NETIF_F_GSO_UDP_TUNNEL_BIT,

	NETIF_F_FCOE_CRC_BIT,		/* FCoE CRC32 */
	NETIF_F_SCTP_CSUM_BIT,		/* SCTP checksum offload */
	NETIF_F_FCOE_MTU_BIT,		/* Supports max FCoE MTU, 2158 bytes*/
	NETIF_F_NTUPLE_BIT,		/* N-tuple filters supported */
	NETIF_F_RXHASH_BIT,		/* Receive hashing offload */
	NETIF_F_RXCSUM_BIT,		/* Receive checksumming offload */
	NETIF_F_NOCACHE_COPY_BIT,	/* Use no-cache copyfromuser */
	NETIF_F_LOOPBACK_BIT,		/* Enable loopback */
	NETIF_F_RXFCS_BIT,		/* Append FCS to skb pkt data */
	NETIF_F_RXALL_BIT,		/* Receive errored frames too */
	NETIF_F_HW_VLAN_STAG_TX_BIT,	/* Transmit VLAN STAG HW acceleration */
	NETIF_F_HW_VLAN_STAG_RX_BIT,	/* Receive VLAN STAG HW acceleration */
	NETIF_F_HW_VLAN_STAG_FILTER_BIT,/* Receive filtering on VLAN STAGs */

	/*
	 * Add your fresh new feature above and remember to update
	 * netdev_features_strings[] in net/core/ethtool.c and maybe
	 * some feature mask #defines below. Please also describe it
	 * in Documentation/networking/netdev-features.txt.
	 */

	/**/NETDEV_FEATURE_COUNT
};

  • netdev_features_strings

net/core/ethtool.c

#define ETHTOOL_DEV_FEATURE_WORDS	((NETDEV_FEATURE_COUNT + 31) / 32)

static const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN] = {
	[NETIF_F_SG_BIT] =               "tx-scatter-gather",
	[NETIF_F_IP_CSUM_BIT] =          "tx-checksum-ipv4",
	[NETIF_F_HW_CSUM_BIT] =          "tx-checksum-ip-generic",
	[NETIF_F_IPV6_CSUM_BIT] =        "tx-checksum-ipv6",
	[NETIF_F_HIGHDMA_BIT] =          "highdma",
	[NETIF_F_FRAGLIST_BIT] =         "tx-scatter-gather-fraglist",
	[NETIF_F_HW_VLAN_CTAG_TX_BIT] =  "tx-vlan-hw-insert",

	[NETIF_F_HW_VLAN_CTAG_RX_BIT] =  "rx-vlan-hw-parse",
	[NETIF_F_HW_VLAN_CTAG_FILTER_BIT] = "rx-vlan-filter",
	[NETIF_F_HW_VLAN_STAG_TX_BIT] =  "tx-vlan-stag-hw-insert",
	[NETIF_F_HW_VLAN_STAG_RX_BIT] =  "rx-vlan-stag-hw-parse",
	[NETIF_F_HW_VLAN_STAG_FILTER_BIT] = "rx-vlan-stag-filter",
	[NETIF_F_VLAN_CHALLENGED_BIT] =  "vlan-challenged",
	[NETIF_F_GSO_BIT] =              "tx-generic-segmentation",
	[NETIF_F_LLTX_BIT] =             "tx-lockless",
	[NETIF_F_NETNS_LOCAL_BIT] =      "netns-local",
	[NETIF_F_GRO_BIT] =              "rx-gro",
	[NETIF_F_LRO_BIT] =              "rx-lro",

	[NETIF_F_TSO_BIT] =              "tx-tcp-segmentation",
	[NETIF_F_UFO_BIT] =              "tx-udp-fragmentation",
	[NETIF_F_GSO_ROBUST_BIT] =       "tx-gso-robust",
	[NETIF_F_TSO_ECN_BIT] =          "tx-tcp-ecn-segmentation",
	[NETIF_F_TSO6_BIT] =             "tx-tcp6-segmentation",
	[NETIF_F_FSO_BIT] =              "tx-fcoe-segmentation",
	[NETIF_F_GSO_GRE_BIT] =		 "tx-gre-segmentation",
	[NETIF_F_GSO_UDP_TUNNEL_BIT] =	 "tx-udp_tnl-segmentation",

	[NETIF_F_FCOE_CRC_BIT] =         "tx-checksum-fcoe-crc",
	[NETIF_F_SCTP_CSUM_BIT] =        "tx-checksum-sctp",
	[NETIF_F_FCOE_MTU_BIT] =         "fcoe-mtu",
	[NETIF_F_NTUPLE_BIT] =           "rx-ntuple-filter",
	[NETIF_F_RXHASH_BIT] =           "rx-hashing",
	[NETIF_F_RXCSUM_BIT] =           "rx-checksum",
	[NETIF_F_NOCACHE_COPY_BIT] =     "tx-nocache-copy",
	[NETIF_F_LOOPBACK_BIT] =         "loopback",
	[NETIF_F_RXFCS_BIT] =            "rx-fcs",
	[NETIF_F_RXALL_BIT] =            "rx-all",
};

dev_ethtool -> ethtool_get_features.

  • veth features

drivers/net/veth.c

#define VETH_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_ALL_TSO |    \
		       NETIF_F_HW_CSUM | NETIF_F_RXCSUM | NETIF_F_HIGHDMA | \
		       NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_CTAG_RX | \
		       NETIF_F_HW_VLAN_STAG_TX | NETIF_F_HW_VLAN_STAG_RX )

static void veth_setup(struct net_device *dev)
{
	ether_setup(dev);

	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;

	dev->netdev_ops = &veth_netdev_ops;
	dev->ethtool_ops = &veth_ethtool_ops;
	dev->features |= NETIF_F_LLTX;
	dev->features |= VETH_FEATURES;
	dev->destructor = veth_dev_free;

	dev->hw_features = VETH_FEATURES;
}
#define NETIF_F_ALL_TSO 	(NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_TSO_ECN)