Index: stable/12/sys/dev/acpica/acpi.c
===================================================================
--- stable/12/sys/dev/acpica/acpi.c
+++ stable/12/sys/dev/acpica/acpi.c
@@ -869,7 +869,7 @@
                 strlcat(buf, buf2, buflen);
         }
     } else {
-        snprintf(buf, buflen, "unknown");
+        snprintf(buf, buflen, "");
     }
     return (0);
 }
Index: stable/12/sys/dev/nvdimm/nvdimm.c
===================================================================
--- stable/12/sys/dev/nvdimm/nvdimm.c
+++ stable/12/sys/dev/nvdimm/nvdimm.c
@@ -560,6 +560,24 @@
 	return (0);
 }
 
+static int
+nvdimm_root_child_location_str(device_t dev, device_t child, char *buf,
+    size_t buflen)
+{
+	ACPI_HANDLE handle;
+	int res;
+
+	handle = nvdimm_root_get_acpi_handle(child);
+	if (handle != NULL)
+		res = snprintf(buf, buflen, "handle=%s", acpi_name(handle));
+	else
+		res = snprintf(buf, buflen, "");
+
+	if (res >= buflen)
+		return (EOVERFLOW);
+	return (0);
+}
+
 static device_method_t nvdimm_methods[] = {
 	DEVMETHOD(device_probe, nvdimm_probe),
 	DEVMETHOD(device_attach, nvdimm_attach),
@@ -582,6 +600,7 @@
 	DEVMETHOD(bus_add_child, bus_generic_add_child),
 	DEVMETHOD(bus_read_ivar, nvdimm_root_read_ivar),
 	DEVMETHOD(bus_write_ivar, nvdimm_root_write_ivar),
+	DEVMETHOD(bus_child_location_str, nvdimm_root_child_location_str),
 	DEVMETHOD_END
 };