diff --git a/sys/amd64/amd64/efirt_machdep.c b/sys/amd64/amd64/efirt_machdep.c
--- a/sys/amd64/amd64/efirt_machdep.c
+++ b/sys/amd64/amd64/efirt_machdep.c
@@ -180,6 +180,25 @@
 	return (pte);
 }
 
+static int
+efi_convattr(uint32_t attr)
+{
+	int mode = -1;
+
+	if ((attr & EFI_MD_ATTR_WB) != 0)
+		mode = VM_MEMATTR_WRITE_BACK;
+	else if ((attr & EFI_MD_ATTR_WT) != 0)
+		mode = VM_MEMATTR_WRITE_THROUGH;
+	else if ((attr & EFI_MD_ATTR_WC) != 0)
+		mode = VM_MEMATTR_WRITE_COMBINING;
+	else if ((attr & EFI_MD_ATTR_WP) != 0)
+		mode = VM_MEMATTR_WRITE_PROTECTED;
+	else if ((attr & EFI_MD_ATTR_UC) != 0)
+		mode = VM_MEMATTR_UNCACHEABLE;
+
+	return (mode);
+}
+
 bool
 efi_create_1t1_map(struct efi_md *map, int ndesc, int descsz)
 {
@@ -190,6 +209,7 @@
 	vm_offset_t va;
 	uint64_t idx;
 	int bits, i, mode;
+	bool map_pz;
 
 	obj_1t1_pt = vm_pager_allocate(OBJT_PHYS, NULL, ptoa(1 +
 	    NPML4EPG + NPML4EPG * NPDPEPG + NPML4EPG * NPDPEPG * NPDEPG),
@@ -238,17 +258,8 @@
 			    (uintmax_t)p->md_pages);
 			goto fail;
 		}
-		if ((p->md_attr & EFI_MD_ATTR_WB) != 0)
-			mode = VM_MEMATTR_WRITE_BACK;
-		else if ((p->md_attr & EFI_MD_ATTR_WT) != 0)
-			mode = VM_MEMATTR_WRITE_THROUGH;
-		else if ((p->md_attr & EFI_MD_ATTR_WC) != 0)
-			mode = VM_MEMATTR_WRITE_COMBINING;
-		else if ((p->md_attr & EFI_MD_ATTR_WP) != 0)
-			mode = VM_MEMATTR_WRITE_PROTECTED;
-		else if ((p->md_attr & EFI_MD_ATTR_UC) != 0)
-			mode = VM_MEMATTR_UNCACHEABLE;
-		else {
+		mode = efi_convattr(p->md_attr);
+		if (mode == -1) {
 			if (bootverbose)
 				printf("EFI Runtime entry %d mapping "
 				    "attributes unsupported\n", i);
@@ -274,6 +285,23 @@
 		VM_OBJECT_WUNLOCK(obj_1t1_pt);
 	}
 
+	TUNABLE_BOOL_FETCH("machdep.efirt.map_pz", &map_pz);
+	if (map_pz) {
+		VM_OBJECT_WLOCK(obj_1t1_pt);
+		pte = efi_1t1_pte(0);
+		/* XXX Assume first entry points to PA 0? */
+		mode = efi_convattr(map->md_attr);
+		if (mode == -1) {
+			printf("EFI Runtime page 0 mapping attributes "
+			    "unsupported\n");
+			mode = VM_MEMATTR_UNCACHEABLE;
+		}
+		bits = pmap_cache_bits(kernel_pmap, mode, false) | X86_PG_RW |
+		    X86_PG_V;
+		pte_store(pte, bits);
+		VM_OBJECT_WUNLOCK(obj_1t1_pt);
+	}
+
 	return (true);
 
 fail: