Re: Deactivating TCP checksumming

[Jeff Garzik]

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