Messages in this thread | | | Date | Fri, 22 Feb 2002 19:00:53 -0500 | From | Ion Badulescu <> | Subject | Re: Need some help with IP/TCP Checksum Offload |
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On Fri, 22 Feb 2002 14:57:22 -0800, harish.vasudeva@amd.com wrote: > > I am trying to offload checksum calculation to my hardware. What i am doing in my driver (kernel 2.4.6) is : > > dev->features = NETIF_F_IP_CHECKSUM; > > Then, in my start_xmit( ) routine, i am parsing for the right headers & when i get the IP/TCP header, i print out the checksum & it is already the right checksum. When does the OS/Protocol offload this task? Am i missing something here?
I haven't looked at this in a long time, but at the time the checksum offloading support was introduced, the IP stack needed both NETIF_F_SG and NETIF_F_IP_CSUM in dev->features before it would start offloading.
The idea was that cksum support without scatter-gather support is useless, because the csum gets calculated essentially for free while copying the data to linearize the skbuf.
Ion
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