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Date: Sat, 4 Feb 2006 18:15:40 +0300
From: Yar Tikhiy <yar@comp.chem.msu.su>
To: Gleb Smirnoff <glebius@FreeBSD.org>, kamal kc <kamal_ckk@yahoo.com>,
	freebsd-net@FreeBSD.org
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Subject: Re: offloading ip checksum calculation to the NIC
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On Fri, Feb 03, 2006 at 03:07:03PM +0300, Gleb Smirnoff wrote:
> On Fri, Feb 03, 2006 at 02:30:54AM -0800, kamal kc wrote:
> k> so what do i need to do if i don't want to calculate 
> k> the ip checksum myself ?
> k> 
> k> right now i am taking off packet from the kernel 
> k> and modifying some of the data content, and 
> k> outputting to the IFQ_HANDOFF myself. and i 
> k> am calculating the checksum myself. 
> k> 
> k> i guess if xl would support the 
> k> hardware checksumming i could use that 
> k> feature. 
> k> 
> k> i am just a beginner and i am not getting
> k> the clear picture. 
> 
> If interfaces has enabled capabilities for checksum offloading, then
> the kernel skips checksum calculation.
> 
> See http://people.freebsd.org/~jlemon/csum.txt

FWIW, the details of hardware-assisted checksumming are also
documented on the mbuf(9) and ifnet(9) manpages.

-- 
Yar