re0 device txcsum issue

Is anyone willing to work with me to help trace down this problem?  It
has been outstanding for a long time and I would dearly like it fixed. 
I'm willing to help in any capacity to trace down the culprit.

To recap, on the re0 device (possibly others) running -current on an
amd64 processor there are times when udp packets get improper checksum
calculations with txcsum set for the interface.  This causes a deadlock
in nfs as the client just contunuously requests this packet and it is
rejected because of the checksum being bad.

Sean