NG_L2CAP_OPT_MTU_SIZE
if (hdr->length != NG_L2CAP_OPT_MTU_SIZE || len < hdr->length)
m_copydata(m, *off, NG_L2CAP_OPT_MTU_SIZE, val);
*off += NG_L2CAP_OPT_MTU_SIZE;