diff --git a/sys/arm64/arm64/machdep.c b/sys/arm64/arm64/machdep.c
--- a/sys/arm64/arm64/machdep.c
+++ b/sys/arm64/arm64/machdep.c
@@ -455,36 +455,25 @@
 	}
 }
 
+/*
+ * Handle the EFI memory map list.
+ *
+ * We will make two passes at this, the first (exclude == false) to populate
+ * physmem with valid physical memory ranges from recognized map entry types.
+ * In the second pass we will exclude memory ranges from physmem which must not
+ * be used for general allocations, either because they are used by runtime
+ * firmware or otherwise reserved.
+ *
+ * Adding the runtime-reserved memory ranges to physmem and excluding them
+ * later ensures that they are included in the DMAP, but excluded from
+ * phys_avail[].
+ *
+ * Entry types not explicitly listed here are ignored and not mapped.
+ */
 static void
-exclude_efi_map_entry(struct efi_md *p, void *argp __unused)
-{
-
-	switch (p->md_type) {
-	case EFI_MD_TYPE_CODE:
-	case EFI_MD_TYPE_DATA:
-	case EFI_MD_TYPE_BS_CODE:
-	case EFI_MD_TYPE_BS_DATA:
-	case EFI_MD_TYPE_FREE:
-		/*
-		 * We're allowed to use any entry with these types.
-		 */
-		break;
-	default:
-		physmem_exclude_region(p->md_phys, p->md_pages * EFI_PAGE_SIZE,
-		    EXFLAG_NOALLOC);
-	}
-}
-
-static void
-exclude_efi_map_entries(struct efi_map_header *efihdr)
-{
-
-	foreach_efi_map_entry(efihdr, exclude_efi_map_entry, NULL);
-}
-
-static void
-add_efi_map_entry(struct efi_md *p, void *argp __unused)
+handle_efi_map_entry(struct efi_md *p, void *argp)
 {
+	bool exclude = *(bool *)argp;
 
 	switch (p->md_type) {
 	case EFI_MD_TYPE_RECLAIM:
@@ -496,7 +485,7 @@
 		/*
 		 * Some UEFI implementations put the system table in the
 		 * runtime code section. Include it in the DMAP, but will
-		 * be excluded from phys_avail later.
+		 * be excluded from phys_avail.
 		 */
 	case EFI_MD_TYPE_RT_DATA:
 		/*
@@ -504,6 +493,12 @@
 		 * region is created to stop it from being added
 		 * to phys_avail.
 		 */
+		if (exclude) {
+			physmem_exclude_region(p->md_phys,
+			    p->md_pages * EFI_PAGE_SIZE, EXFLAG_NOALLOC);
+			break;
+		}
+		/* FALLTHROUGH */
 	case EFI_MD_TYPE_CODE:
 	case EFI_MD_TYPE_DATA:
 	case EFI_MD_TYPE_BS_CODE:
@@ -512,8 +507,12 @@
 		/*
 		 * We're allowed to use any entry with these types.
 		 */
-		physmem_hardware_region(p->md_phys,
-		    p->md_pages * EFI_PAGE_SIZE);
+		if (!exclude)
+			physmem_hardware_region(p->md_phys,
+			    p->md_pages * EFI_PAGE_SIZE);
+		break;
+	default:
+		/* Other types shall not be handled by physmem. */
 		break;
 	}
 }
@@ -521,7 +520,15 @@
 static void
 add_efi_map_entries(struct efi_map_header *efihdr)
 {
-	foreach_efi_map_entry(efihdr, add_efi_map_entry, NULL);
+	bool exclude = false;
+	foreach_efi_map_entry(efihdr, handle_efi_map_entry, &exclude);
+}
+
+static void
+exclude_efi_map_entries(struct efi_map_header *efihdr)
+{
+	bool exclude = true;
+	foreach_efi_map_entry(efihdr, handle_efi_map_entry, &exclude);
 }
 
 static void