VR_CSUM_FEATURES
if (((*m_head)->m_pkthdr.csum_flags & VR_CSUM_FEATURES) != 0) {
if_sethwassistbits(ifp, VR_CSUM_FEATURES, 0);
if_sethwassistbits(ifp, 0, VR_CSUM_FEATURES);
if_sethwassist(ifp, VR_CSUM_FEATURES);