Index: sys/kern/subr_physmem.c
===================================================================
--- sys/kern/subr_physmem.c
+++ sys/kern/subr_physmem.c
@@ -390,7 +390,7 @@
 /*
  * Add a hardware memory region.
  */
-void
+int
 physmem_hardware_region(uint64_t pa, uint64_t sz)
 {
 	vm_offset_t adj;
@@ -401,12 +401,12 @@
 	 */
 	if (pa == 0) {
 		if (sz <= PAGE_SIZE)
-			return;
-		pa  = PAGE_SIZE;
+			return (0);
+		pa = PAGE_SIZE;
 		sz -= PAGE_SIZE;
 	} else if (pa > MAX_PHYS_ADDR) {
 		/* This range is past usable memory, ignore it */
-		return;
+		return (ERANGE);
 	}
 
 	/*
@@ -423,7 +423,7 @@
 	if ((pa + sz) > (MAX_PHYS_ADDR - 1024 * 1024)) {
 		sz = MAX_PHYS_ADDR - pa + 1;
 		if (sz <= 1024 * 1024)
-			return;
+			return (0);
 		sz -= 1024 * 1024;
 	}
 
@@ -435,14 +435,18 @@
 	pa  = round_page(pa);
 	sz  = trunc_page(sz - adj);
 
-	if (sz > 0 && hwcnt < nitems(hwregions))
-		hwcnt = insert_region(hwregions, hwcnt, pa, sz, 0);
+	if (sz == 0)
+		return (EINVAL);
+	if (hwcnt == nitems(hwregions))
+		return (E2BIG);
+	hwcnt = insert_region(hwregions, hwcnt, pa, sz, 0);
+	return (0);
 }
 
 /*
  * Add an exclusion region.
  */
-void
+int
 physmem_exclude_region(vm_paddr_t pa, vm_size_t sz, uint32_t exflags)
 {
 	vm_offset_t adj;
@@ -455,10 +459,10 @@
 	pa  = trunc_page(pa);
 	sz  = round_page(sz + adj);
 
-	if (excnt >= nitems(exregions))
-		panic("failed to exclude region %#jx-%#jx", (uintmax_t)pa,
-		    (uintmax_t)(pa + sz));
+	if (excnt == nitems(exregions))
+		return (E2BIG);
 	excnt = insert_region(exregions, excnt, pa, sz, exflags);
+	return (0);
 }
 
 size_t
Index: sys/sys/physmem.h
===================================================================
--- sys/sys/physmem.h
+++ sys/sys/physmem.h
@@ -49,8 +49,8 @@
 #define	EXFLAG_NODUMP	0x01
 #define	EXFLAG_NOALLOC	0x02
 
-void physmem_hardware_region(uint64_t pa, uint64_t sz);
-void physmem_exclude_region(vm_paddr_t pa, vm_size_t sz, uint32_t flags);
+int physmem_hardware_region(uint64_t pa, uint64_t sz);
+int physmem_exclude_region(vm_paddr_t pa, vm_size_t sz, uint32_t flags);
 size_t physmem_avail(vm_paddr_t *avail, size_t maxavail);
 void physmem_init_kernel_globals(size_t *pa_idx, size_t *da_idx);
 void physmem_print_tables(void);