Date: Mon, 10 May 2010 22:49:17 +0200 From: Andrea Venturoli <ml@netfence.it> To: freebsd-net@freebsd.org Subject: Warnings with TSO on em Message-ID: <4BE8714D.8080608@netfence.it>
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Hello. For quite a while, I've been seeing in the logs a lot of messages like the following: snort: (snort_decoder) WARNING: IP dgm len < IP Hdr len! I'm not sure about this, but I suspect they started when I upgraded from 6.3 to 7.2. Today, while investigating another problem, I decided I had to move this out of the way; tcpdump showed zero-length IP packets and Google told me they might be the result of TSO on the em cards. So I checked and, yes, I had TSO enabled (by default). "ifconfig em0 -tso" made this noise go away. Now I'm looking for some more insight: if it's only a performance problem, I don't think I'll be hit, but could there be other side effects? # uname -a FreeBSD xxxxx.xxxxxxxx.xx 7.2-RELEASE-p7 FreeBSD 7.2-RELEASE-p7 #9: ... # pciconf -l|grep em em0@pci0:6:0:0: class=0x020000 card=0x34768086 chip=0x10968086 rev=0x01 hdr=0x00 em1@pci0:6:0:1: class=0x020000 card=0x34768086 chip=0x10968086 rev=0x01 hdr=0x00 I found some thread suggesting this might possibly be a bug with the em driver, but there was no follow up for more than a year. bye & Thanks av. P.S. I had another problem on this machine: when I bonded the the two "em" interfaces into a "lagg" one, carp stopped working properly. Now I wonder if the two issues might be related...
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