Ubuntu
isc-dhcp package

  1. Bug #930962
  2. Comment #21

Comment 21 for bug 930962

Revision history for this message
Michal Suchanek (hramrach) wrote : Re: [Bug 930962] Re: dhcp3-server reports many bad udp checksums to syslog using virtio NIC

Hello,

On 8 January 2013 15:01, Martijn Lievaart <email address hidden> wrote:

> Hi Michal,
>
> I don't quite understand what you are saying here. Are you saying that
> because Linux has a kernel interface to check for offloading, any and
> all application (that cares about udp checksums) should use this? It

Yes, reading several discussion about this issue it seems that
application that wants to work correctly on Linux has to do this. This
issue pops up on actual hardware with actual hardware checksum
offloading reportedly.

> would seem much simpler if the virtio driver zero'd the checksum field,
> any application already should be able to handle that. No Linux specific
> code needed.

Except virtio would have to do the work then. Also it does not solve
the issue for other hardware with offloading.

Also does the zero checksum not change the meaning of the message? It
would seem that setting the checksum to zero in driver and application
ignoring the offload status would imply interpretation that the sender
did not include any checksum at all whereas the correct interpretation
would be that the checksum was verified and stripped by network
hardware.

Thanks

Michal