I tested again with the latest igbvf module which compiles fine on my Ubuntu system but I'm still hitting the same issue.
igb: 4.1.2-k
igbvf: 2.3.2
kernel: 3.8.0-26
iproute2: iproute2-ss130716
$ ip link set p5p2 vf 1 spoofchk off
RTNETLINK answers: Operation not supported
Any hint?
Thanks!