offloading ip checksum calculation to the NIC

[kamal kc]

--- Gleb Smirnoff <glebius at FreeBSD.org> wrote:

> On Thu, Feb 02, 2006 at 10:20:46PM -0800, kamal kc wrote:
> k> i want to offload ip checksum calculation to the NIC.
> k> I use 3Com 3c905B-TX NIC cards.
> k> 
> k> I found that there are variables::>>
> k> 
> k>         int	csum_flags;		/* flags regarding checksum */
> k> 	int	csum_data;		/* data field used by csum routines */
> k> 
> k> in struct pkthdr in mbuf.h.
> k> 
> k> also i found the various flags for the hardware checksumming.
> k> but i don't know the exact steps i need to do 
> k> in order to offload checksumming. 
> k> 
> k> should i set the csum_flags to CSUM_IP and point
> k> csum_data to the start of the ip header ??
> k> 
> k> it would be a great help if anybody
> k> could tell me what do i need to do ?
> 
> afaik, the xl(4) driver already supports checksum calculation.
> 
> -- 
so what do i need to do if i don't want to calculate 
the ip checksum myself ?

right now i am taking off packet from the kernel 
and modifying some of the data content, and 
outputting to the IFQ_HANDOFF myself. and i 
am calculating the checksum myself. 

i guess if xl would support the 
hardware checksumming i could use that 
feature. 

i am just a beginner and i am not getting
the clear picture. 

thanks,
kamal














 


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com