CDCEEM_DATA_LEN_MASK
pktlen = hdr & CDCEEM_DATA_LEN_MASK;
KASSERT((m->m_pkthdr.len & CDCEEM_DATA_LEN_MASK) == m->m_pkthdr.len,
m->m_pkthdr.len, m->m_pkthdr.len & CDCEEM_DATA_LEN_MASK));