physmem: zero entire array

As a convenience to callers, who might allocate the array on the stack.
An empty/zero-valued range indicates the end of the physmap entries.

Remove the now-redundant calls to bzero() at the call site.

Reviewed by:	andrew
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D45318

sys/arm64/arm64/pmap.c

@@ -1437,7 +1437,6 @@ pmap_bootstrap_san1(vm_offset_t va, int scale)
 	 * Rebuild physmap one more time, we may have excluded more regions from
 	 * allocation since pmap_bootstrap().
 	 */
-	bzero(physmap, sizeof(physmap));
 	physmap_idx = physmem_avail(physmap, nitems(physmap));
 	physmap_idx /= 2;
 

sys/kern/subr_physmem.c

@@ -189,6 +189,8 @@ regions_to_avail(vm_paddr_t *avail, uint32_t exflags, size_t maxavail,
 	const struct region *exp, *hwp;
 	uint64_t availsz;
 
+	bzero(avail, maxavail * sizeof(vm_paddr_t));
+
 	totalmem = 0;
 	availmem = 0;
 	availsz = 0;
@@ -587,7 +589,6 @@ ram_attach(device_t dev)
 	rid = 0;
 
 	/* Get the avail list. */
-	bzero(avail_list, sizeof(avail_list));
 	regions_to_avail(avail_list, EXFLAG_NOALLOC | EXFLAG_NODUMP,
 	    PHYS_AVAIL_COUNT, 0, NULL, NULL);