Hardware Checksum Offload

To get data about support for hardware checksum offload, the framework sends MAC_CAPAB_HCKSUM in the cap argument. See Hardware Checksum Offload Capability Information.

To query checksum offload metadata and retrieve the per-packet hardware checksumming metadata when hardware checksumming is enabled, use mac_hcksum_get(9F). See The mac_hcksum_get() Function Flags.

To set checksum offload metadata, use mac_hcksum_set(9F). See The mac_hcksum_set() Function Flags.

See Hardware Checksumming: Hardware and Hardware Checksumming: MAC Layer for more information.

Hardware Checksum Offload Capability Information

To pass information about the MAC_CAPAB_HCKSUM capability to the framework, the driver must set a combination of the following flags in cap_data, which points to a uint32_t. These flags indicate the level of hardware checksum offload that the driver is capable of performing for outbound packets.

HCKSUM_INET_PARTIAL

Partial 1's complement checksum ability

HCKSUM_INET_FULL_V4

Full 1's complement checksum ability for IPv4 packets

HCKSUM_INET_FULL_V6

Full 1's complement checksum ability for IPv6 packets

HCKSUM_IPHDRCKSUM

IPv4 Header checksum offload capability

The mac_hcksum_get() Function Flags

The flags argument of mac_hcksum_get() is a combination of the following values:

HCK_FULLCKSUM

Compute the full checksum for this packet.

HCK_FULLCKSUM_OK

The full checksum was verified in hardware and is correct.

HCK_PARTIALCKSUM

Compute the partial 1's complement checksum based on other parameters passed to mac_hcksum_get(). HCK_PARTIALCKSUM is mutually exclusive with HCK_FULLCKSUM.

HCK_IPV4_HDRCKSUM

Compute the IP header checksum.

HCK_IPV4_HDRCKSUM_OK

The IP header checksum was verified in hardware and is correct.

The mac_hcksum_set() Function Flags

The flags argument of mac_hcksum_set() is a combination of the following values:

HCK_FULLCKSUM

The full checksum was computed and passed through the value argument.

HCK_FULLCKSUM_OK

The full checksum was verified in hardware and is correct.

HCK_PARTIALCKSUM

The partial checksum was computed and passed through the value argument. HCK_PARTIALCKSUM is mutually exclusive with HCK_FULLCKSUM.

HCK_IPV4_HDRCKSUM

The IP header checksum was computed and passed through the value argument.

HCK_IPV4_HDRCKSUM_OK

The IP header checksum was verified in hardware and is correct.