MPT_REQ_MEM_SIZE
error = bus_dmamem_alloc(mpt->sc_dmat, MPT_REQ_MEM_SIZE(mpt),
MPT_REQ_MEM_SIZE(mpt), (void **) &mpt->request, 0);
error = bus_dmamap_create(mpt->sc_dmat, MPT_REQ_MEM_SIZE(mpt), 1,
MPT_REQ_MEM_SIZE(mpt), 0, 0, &mpt->request_dmap);
MPT_REQ_MEM_SIZE(mpt), NULL, 0);
end = pptr + MPT_REQ_MEM_SIZE(mpt);