On Monday 30 July 2007 22:32, Andrew Gallatin wrote:
Second, you still need to set skb->ip_summed = CHECKSUM_UNNECESSARY
when modified packets are flushed, else the stack will see bad
checksums for packets from CHECKSUM_COMPLETE drivers using the
skb interface. Fixed in the attached patch.
I thought about it... As we do update the TCP checksum for aggregated
packets we could add a second ip_summed field in the net_lro_mgr struct used for aggregated packets to support HW that does not have any checksum helper
functionality. These drivers could set this ip_summed field to CHECKSUM_NONE, and thus leave the checksum check to the stack. I'm not sure if these old devices benefit
a lot from LRO. So what do you think?
Fourth, I did some traffic sniffing to try to figure out what's going
on above, and saw tcpdump complain about bad checksums. Have you tried
running tcpdump -s 65535 -vvv? Have you also seen bad checksums?
I seem to see this for both page- and skb-based versions of the driver.
Hmmm, can't confirm that. For our skb-based version I see
correct checksums for aggregated packets and for the page-based version as well.
I used: (tcpdump -i ethX -s 0 -w dump.bin) in combination with ethereal.
Don't see problems as well with your tcpdump command.