On 09.08.2012 10:21, Michal Suchanek wrote: >> of this goes it would be not critical in importance because clients seem >> to get an IP address even with those messages showing up. > > That's not what I see here, they do not get an IP address.
Then what is your exact setup? >> - virtio (and xen netfron) would deliberately leave the checksum incomplete >> for >> packets between interfaces on the same host because the packet will always >> remain in memory. So calculating a checksum is a waste of time. > > No, that's how any network card with checksum offloading behaves. It > may skip copying the checksum because it verified it already, and the > virtio device abuses this interface quirk to never produce any > checksum in the first place. On real network interfaces you can turn > that feature off, and then the checksum is always copied. On virtio > 'turning off' would amount to producing a checksum which dhclient can > subsequently check. Yes, it a real card has checksum offloading it would do this in hardware. What I try to say is that the fact that virtio leaves them incomplete when passed within the virtual network looks like a deliberate decision there for performance improvement. And since upstream has added that interface to check for those incomplete checksums (and specifically mentioning dhcp) makes it clear that the drivers will not change. -- 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
