bzero(zerop, PAGE_SIZE);
bzero(zerop, NBPG);				 *zero_pte = 0;
pmap_zero_page(pa)	paddr_t pa;{	simple_lock(&pmap_zero_page_lock);	*zero_pte = (pa & PG_FRAME) | PG_V | PG_RW;	/* map in */	bzero(zerop, PAGE_SIZE);				/* zero */	pmap_update_pg((vaddr_t)zerop);		/* flush TLB */	simple_unlock(&pmap_zero_page_lock);}