TCP receive checksum offloading

TCP receive checksum offloading

Post by Slawom » Wed, 14 May 2003 02:00:47



e1000 driver for Intel's Gigabit cards claims support for TCP checksum
calculation offload on both receive and transmit side. It is possible
to verify that claim with the sendfile() syscall on the transmit side.
However, sendfile() can not read from a socket.
Is there a way to benefit from TCP checksum offloading on the receive
side in 2.4.x or 2.5.x kernel?

Thanks,
Slawomir

 
 
 

1. seeking how to use TCP Checksum Off-load in my network driver

I am seeking infomation on how to use TCP Checksum Off-load to tell
the Solaris 8 stack not to handle it for both receives and transmits
(and let our NIC handle this compute-intensive task instead).

There is mention that Sun GigabitEthernet Adapter cards, Release 1.1
supports Sol-2.6 use of NIC features: TCP checksum offload & byte
swapping

There are limited bits of info in include files. For example

sys/strick.h indicates use of:
inetcksum_t's ick_xmit

stream.h has:
struct datab's unsigned u16:16; /* used to store hw-calculated cksum
*/

#define STRUIO_IP 0x04 /* IP checksum stored in db_struioun */
#define STRUIO_ZC 0x08 /* mblk eligible for zero-copy */

strsub.h has:
struct zero_copy_kstat

Also /include/inet/tcp.h has tcp_sum field for outbound segments.

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