XN_M_CSUM_SUPPORTED
m->m_pkthdr.csum_flags = XN_M_CSUM_SUPPORTED;
if (m->m_pkthdr.csum_flags & XN_M_CSUM_SUPPORTED) {
if ((xst0->xs_m->m_pkthdr.csum_flags & XN_M_CSUM_SUPPORTED) != 0) {
XN_M_CSUM_SUPPORTED;