Question is where is this zero checksum observed which is not clear from the report.
If in the guest it is certainly correct. If in the host it is correct so long as the bridge appears to have checksum offloading as well. If whatever interface the guest packets appear to come from is not set up with checksum offloading this is a bug which should be fixed by setting the offload flags to match the guest. If outside the host this is a problem. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1192464 Title: udp checksum computed as 0 not converted to 0xffff, from guest os that share a common linux bridge among multiple guest os Status in QEMU: Incomplete Bug description: UDP checksum computed as '0' during transmission of packets that uses e1000 NIC in the Guest as well as emulated h/w in the qemu layer, That needs to be converted to 0xffff, This occurs only when Hardware checksum offload is been set in the guest OS NIC and made it as a transmitter. The guest O.S use the N/W interface that is been shared to the linux brige created in the host (used source=<bridge>) in the xml tags of libvirt. As per RFC768(http://tools.ietf.org/html/rfc768 [^]), If the computed checksum is zero, it is transmitted as all ones (the equivalent in one's complement arithmetic). An all zero transmitted checksum value means that the transmitter generated no checksum (for debugging or for higher level protocols that don't care). To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1192464/+subscriptions
