RE: Deactivating TCP checksumming

["Dennis Cook" <cook@sandgate.com>]

In the 3c59x.c, e1000, and other adapter drivers, ip_summed is
what is being checked for value CHECKSUM_HW when sending
a packet.

> -----Original Message-----
> From: Jeff Garzik [mailto:jgarzik@pobox.com]
> Sent: Thursday, April 03, 2003 03:47 PM
> To: Dennis Cook
> Cc: linux-kernel@vger.kernel.org; kernelnewbies@nl.linux.org
> Subject: Re: Deactivating TCP checksumming
> 
> 
> Dennis Cook wrote:
> > Based on various feedback, on my RH Linux 2.4.18 kernel I tried the
> > following:
> > 
> > Set "features" bit NETIF_F_IP_CSUM set (the only feature bit set).
> > In my network driver start-transmit check for "CHECKSUM_HW" in 
> ip_summed.
> > Using a small test program, use "sendfile" to copy a file to a network
> > socket FD.
> > Result is none of the packets presented to my network adapter 
> driver have
> > ip_summed set to CHECKSUM_HW, so the SW IP stack has already
> > computed checksums.
> 
> CHECKSUM_HW is for receive, not transmit.  Read the comments at the top 
> of include/linux/skbuff.h.
> 
> 
> > Is this mechanism possibly broken on kernel 2.4?
> 
> 
> it works quite well.
> 
> 	Jeff
> 
> 
> 
> 

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