On 14 Mar 2014, at 06:20, Hooman Fazaeli <hoomanfazaeli at gmail.com> wrote: > Hi list, > > Is it safe to use m->m_pktdat area to store some arbitrary data about packets allocated as mbuf+cluster pair? No, because m_pktdat is really MH_databuf which is part of a union with MH_ext which is set when you allocate an mbuf cluster. -- Rui Paulo