dt_pcb_alloc
dp = dt_pcb_alloc(dtp, sc);
dp = dt_pcb_alloc(dtp, sc);
dp = dt_pcb_alloc(dtp, sc);
dp = dt_pcb_alloc(dtp, sc);
struct dt_pcb *dt_pcb_alloc(struct dt_probe *, struct dt_softc *);