Date: Tue, 19 Jan 2016 18:37:05 -0500 From: Garrett Wollman <wollman@freebsd.org> To: freebsd-net@freebsd.org Subject: Another issue with ixl(4) with netmap Message-ID: <22174.51361.2022.984959@hergotha.csail.mit.edu>
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I noticed that a large number -- but by no means all -- of the packets captured using libpcap on a netmap'ified ixl(4) interface show up as truncated -- usually by exactly four bytes. They show up in tcpdump like this: 18:10:05.348735 IP truncated-ip - 4 bytes missing! 128.30.xxx.xxx.443 > yyy.yyy.yyy.yyy.54711: Flags [P.], seq 3151716053:3151716112, ack 3109956633, win 31, length 59 18:10:05.348735 IP truncated-ip - 4 bytes missing! zzz.zzz.zzz.zzz.17376 > 128.30.aaa.aaa.80: Flags [.], ack 1771224170, win 12775, options [nop,nop,sack 1 [|tcp]> 18:10:05.348735 IP truncated-ip - 4 bytes missing! zzz.zzz.zzz.zzz.17376 > 128.30.aaa.aaa.80: Flags [.], ack 1, win 12775, options [nop,nop,sack 1 [|tcp]> This does not occur when the same interface is used with BPF (but libpcap can't keep up with the traffic when using BPF). Has anyone see this before, and if so, what was the solution? (This is on 10.2 with the ixl(4) updates merged from 10-stable.) -GAWollman
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