M_LASTFRAG
if (m0->m_flags & M_LASTFRAG)
frag = ((buf->m->m_flags & (M_FRAG | M_LASTFRAG)) == M_FRAG);
M_AMPDU_MPDU|M_FRAG|M_FIRSTFRAG|M_LASTFRAG)
m->m_flags |= M_LASTFRAG;