diff --git a/sys/conf/files b/sys/conf/files
index ef5e59bb5d2c..4b61f170ede0 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -274,6 +274,7 @@ dev/aac/aac_disk.c	optional aac
 dev/aac/aac_pci.c	optional aac pci
 dev/aac/aac_cam.c	optional aacp aac
 dev/aac/aac_linux.c		optional aac compat_linux
+dev/acpica/acpi_if.m		standard
 dev/acpica/acpi.c		optional acpi
 dev/acpica/acpi_acad.c		optional acpi
 dev/acpica/acpi_battery.c	optional acpi
diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk
index 69538753a0ba..39cca2c26268 100644
--- a/sys/conf/kmod.mk
+++ b/sys/conf/kmod.mk
@@ -293,7 +293,7 @@ ${_src}:
 MFILES?= kern/bus_if.m kern/device_if.m dev/iicbus/iicbb_if.m \
     dev/iicbus/iicbus_if.m isa/isa_if.m \
     libkern/iconv_converter_if.m \
-    dev/eisa/eisa_if.m dev/mii/miibus_if.m \
+    dev/acpica/acpi_if.m dev/eisa/eisa_if.m dev/mii/miibus_if.m \
     dev/pccard/card_if.m dev/pccard/power_if.m dev/pci/pci_if.m \
     dev/pci/pcib_if.m dev/ppbus/ppbus_if.m dev/smbus/smbus_if.m \
     dev/usb/usb_if.m dev/sound/pcm/ac97_if.m dev/sound/pcm/channel_if.m \
diff --git a/sys/dev/acpica/acpi_if.m b/sys/dev/acpica/acpi_if.m
new file mode 100644
index 000000000000..c2cdc1121e18
--- /dev/null
+++ b/sys/dev/acpica/acpi_if.m
@@ -0,0 +1,77 @@
+#
+# Copyright (c) 2004 Nate Lawson
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+#
+
+#include <sys/bus.h>
+#include <sys/types.h>
+#include "acpi.h"
+
+INTERFACE acpi;
+
+#
+# Default implementation for the probe method.
+#
+CODE {
+	static char *
+	acpi_generic_id_probe(device_t bus, device_t dev, char **ids)
+	{
+		return (NULL);
+	}
+};
+
+#
+# Probe
+#
+METHOD char * id_probe {
+	device_t	bus;
+	device_t	dev;
+	char		**ids;
+} DEFAULT acpi_generic_id_probe;
+
+#
+# AcpiEvaluateObject
+#
+METHOD ACPI_STATUS evaluate_object {
+	device_t	bus;
+	device_t	dev;
+	ACPI_STRING 	pathname;
+	ACPI_OBJECT_LIST *parameters;
+	ACPI_BUFFER	*ret;
+};
+
+#
+# AcpiWalkNamespace
+#
+METHOD ACPI_STATUS walk_namespace {
+	device_t	bus;
+	device_t	dev;
+	ACPI_OBJECT_TYPE type;
+	UINT32		max_depth;
+	ACPI_WALK_CALLBACK user_fn;
+	void		*context;
+	void		**ret;
+};