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Date:      Fri, 28 Sep 2001 01:01:20 -0700
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Jonathan Lemon <jlemon@flugsvamp.com>
Cc:        the_srinivas@hotmail.com, hackers@freebsd.org
Subject:   Re: TCP&IP cksum offload on FreeBSD 4.2
Message-ID:  <3BB42E50.B32F5E95@mindspring.com>
References:  <200109270157.f8R1vZ546863@prism.flugsvamp.com>

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Jonathan Lemon wrote:
> >I'm trying to use the TCP&IP checksum offload capability of the Netgear
> >GA620 NIC from a SMP FreeBSD 4.2R system running on a typical PIII SBC.
> >I did enable TCP&IP cksum offload for receive operations by setting the
> >if_hwassist flag in the driver /sys/pci/if_ti.c and verified that it is
> >working. However I'm unable to offload TCP&IP checksum for the send
> >operations.
> 
> All you need to do is uncomment the TI_CSUM_FEATURES flag at the top
> of the file, and recompile.

He didn't say his packet size, either.

To the original poster: if you are sending jumbograms, the
buffer size on these cards is limited, so the entire packet
can't be in the card buffer at the same time, which means
that you can not offload the send checksum for jumbograms,
only for regular sized packets.

Also note that this card is not known to be the fastest
one ot there, so you may be better off doing the checksum
on your 1GHz+ host processor instead.

-- Terry

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