Manual Pages for UNIX Operating System command usage for man mac_hcksum_get

Kernel Functions for Drivers                   mac_hcksum_get(9F)



NAME
     mac_hcksum_get,  mac_hcksum_set  -   hardware   checksumming
     offload routines

SYNOPSIS
     #include 

     void mac_hcksum_get(mblk_t *mp, uint32_t *start, uint32_t *stuff,
         uint32_t *end, uint32_t *value, uint32_t *flags);


     void mac_hcksum_set(mblk_t *mp, uint32_t start, uint32_t stuff,
         uint32_t end, uint32_t value, uint32_t *flags);


PARAMETERS
     mp       pointer to a message block


     start    offset, in bytes, from the start of the  IP  header
              to the start of the checksum span


     end      offset, in bytes, from the start of the  IP  header
              to the end of the checksum span


     stuff    offset, in bytes, from the start of the  IP  header
              to the checksum field in the protocol header


     value    hardware computed checksum value


     flags    per-packet flags indicating the hardware  checksum-
              ming  to  be  performed on outbound packets, or the
              hardware checksumming performed on inbound packet


INTERFACE LEVEL
     Solaris architecture specific (Solaris DDI)

DESCRIPTION
     Hardware checksumming allows the checksum computation to  be
     offloaded to the network device hardware for lower CPU util-
     ization. Hardware checksumming capabilities  are  advertised
     from  the driver's mc_getcapab(9E) entry point. The descrip-
     tion of mc_getcapab() also includes more  information  about
     the expected behavior of drivers for full and partial check-
     summing offload.





SunOS 5.11          Last change: 26 Jul 2010                    1






Kernel Functions for Drivers                   mac_hcksum_get(9F)



     For received  traffic,  the  hardware  can  enable  hardware
     checksumming,  and the network stack will know how to handle
     packets for which checksum computation or  verification  has
     been  performed.   The mac_hcksum_set() function can be used
     by a device driver to associate information related  to  the
     hardware checksumming performed on the packet.


     The flags argument can be a combination of the following:

     HCK_FULLCKSUM           The full checksum was computed,  and
                             is  passed  through  the value argu-
                             ment.


     HCK_FULLCKSUM_OK        The full checksum  was  verified  in
                             hardware and is correct.


     HCK_PARTIALCKSUM        Partial checksum computed and passed
                             through   the  value  argument.  The
                             start and end arguments specify  the
                             checksum span.


     HCK_IPV4_HDRCKSUM_OK    IP header checksum was  verified  in
                             hardware and is correct.



     HCK_PARTIALCKSUM   is   mutually    exclusive    with    the
     HCK_FULLCKSUM and HCK_FULLCKSUM_OK flags.


     For outbound packets, hardware checksumming capabilities are
     queried  via  the mc_getcapab() entry point. Hardware check-
     summing is  enabled  by  the  network  stack  based  on  the
     MAC_CAPAB_HCKSUM capability. A device driver that advertised
     support for this capability can  subsequently  receive  out-
     bound  packets  that may not have a fully computed checksum.
     It  is  the  responsibility  of   the   driver   to   invoke
     mac_hcksum_get()  to retrieve the per-packet hardware check-
     summing metadata.

     HCK_FULLCKSUM        Compute full checksum for this packet.


     HCK_PARTIALCKSUM     Compute partial 1's complement checksum
                          based on the start, stuff, and offset.






SunOS 5.11          Last change: 26 Jul 2010                    2






Kernel Functions for Drivers                   mac_hcksum_get(9F)



     HCK_IPV4_HDRCKSUM    Compute the IP header checksum.



     HCK_PARTIALCKSUM is mutually exclusive with HCK_FULLCKSUM.


     The    flags    HCK_FULLCKSUM,     HCK_FULLCKSUM_OK,     and
     HCK_PARTIALCKSUM  are  used  for both IPv4 and IPv6 packets.
     The driver advertises support  for  IPv4  and/or  IPv6  full
     checksumming     during    capability    negotiation.    See
     mc_getcapab(9E).

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWhea                     |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|


SEE ALSO
     attributes(5), mac(9E)

























SunOS 5.11          Last change: 26 Jul 2010                    3