WSWAPrbd
rbd->b_next = WSWAPrbd(virt_to_bus(rbd+1));
rbd->b_addr = WSWAPrbd(virt_to_bus(rbd));
rbd->b_next = WSWAPrbd(virt_to_bus(lp->rbds));
lp->rfds[0].rbd = WSWAPrbd(virt_to_bus(lp->rbds));