dpt_sg_t
dpt_sg_t *sg_list;
dpt_sg_t* sg_vaddr;
dpt_sg_t *segs;
newcount = (PAGE_SIZE / (dpt->sgsize * sizeof(dpt_sg_t)));
physaddr += (dpt->sgsize * sizeof(dpt_sg_t));
dpt_sg_t *sg;
htonl(nseg * sizeof(dpt_sg_t));