On 7 January 2013 23:13, Martijn Lievaart <930...@bugs.launchpad.net> wrote: > According to my cursory reading of relevant RFCs and a quick wireshark > session, the bug is in KVM virtio. An UDP packet should contain a > checksum field of 0 for no checksum, or a correct checksum. I see bogus > values coming in. > > OTOH, wireshark warns that this may be due to offloading, so I may not > be correct in this analysis. >
This is due to virtio implementing 'offloading' by returning random garbage in the checksum field. Since the code to calculate the checksumis not present this offloading cannot be turned off. Since kernel has interface to inform applications that offloading is on it is a bug in the application to interpret the bogus checksum. Presumably the card has already checked it and did not bother passing it on. This same feature is available on real e1000 hardware and can be turned off there. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/930962 Title: dhcp3-server reports many bad udp checksums to syslog using virtio NIC To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/isc-dhcp/+bug/930962/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
