Some platforms have rules for retrieving the MAC address for an interface

beyond what properties exist.  For example, a local address maybe be
present in a device tree property, but a system-wide property may indicate
that it should not be used (in favor of e.g. a singular system MAC addres -
LOOKIN' AT YOU, SUNW!).

So, the ether-get-mac-address device call is introduced to handle this
situation.  Consult it before the standard properites, and if it succeeds,
use its result.

Author: thorpej

sys/net/Makefile

@@ -1,4 +1,4 @@
-#	$NetBSD: Makefile,v 1.46 2022/09/03 02:47:59 thorpej Exp $
+#	$NetBSD: Makefile,v 1.47 2025/10/12 23:41:09 thorpej Exp $
 
 INCSDIR= /usr/include/net
 
@@ -13,6 +13,12 @@ INCS=	bpf.h bpfjit.h bpfdesc.h dlt.h ethertypes.h if.h if_arc.h if_arp.h \
 
 SUBDIR=	agr npf lagg
 
+ether_calls.h: ${.CURDIR}/ether_calls
+	echo "${TOOL_AWK} -f ${.CURDIR}/../kern/gendevcalls.awk \
+	    ${.CURDIR}/ether_calls > ${.CURDIR}/ether_calls.h"
+	${TOOL_AWK} -f ${.CURDIR}/../kern/gendevcalls.awk \
+	    ${.CURDIR}/ether_calls > ${.CURDIR}/ether_calls.h
+
 .include <bsd.kinc.mk>
 
 .PATH: ${NETBSDSRCDIR}/sys/dist/pf/net

sys/net/ether_calls

@@ -0,0 +1,55 @@
+$NetBSD: ether_calls,v 1.1 2025/10/12 23:41:08 thorpej Exp $
+
+/*-
+ * Copyright (c) 2025 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Jason R. Thorpe.
+ *
+ * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+/*
+ * Device calls used by the Ethernet subsystem.
+ */
+
+subsystem ether;
+
+#include <net/if_ether.h>
+
+/*
+ * ether-get-mac-address
+ *
+ * Retrieve the MAC address for the Ethernet interface associated
+ * with the device handle.
+ *
+ * While it is common for platform device trees to provide the MAC
+ * address in a property, some platforms may use single system-wide
+ * MAC address in addition to interface-specific addresses, and the
+ * rules about which one to use on a given interface are encoded into
+ * the device tree itself, hence this hook.
+ */
+ether-get-mac-address {
+	/* This buffer is assumed to be ETHER_ADDR_LEN bytes in size. */
+	uint8_t *	enaddr;		/* OUT */
+};

sys/net/ether_calls.h

@@ -0,0 +1,83 @@
+/*	$NetBSD: ether_calls.h,v 1.1 2025/10/12 23:41:08 thorpej Exp $	*/
+
+/*
+ * THIS FILE IS AUTOMATICALLY GENERATED.  DO NOT EDIT.
+ *
+ * generated from:
+ *	NetBSD
+ */
+
+/*-
+ * Copyright (c) 2025 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Jason R. Thorpe.
+ *
+ * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+/*
+ * Device calls used by the Ethernet subsystem.
+ */
+
+#ifndef _ETHER_CALLS_H_
+#define _ETHER_CALLS_H_
+
+#include <sys/device.h>
+
+#include <net/if_ether.h>
+
+/*
+ * ether-get-mac-address
+ *
+ * Retrieve the MAC address for the Ethernet interface associated
+ * with the device handle.
+ *
+ * While it is common for platform device trees to provide the MAC
+ * address in a property, some platforms may use single system-wide
+ * MAC address in addition to interface-specific addresses, and the
+ * rules about which one to use on a given interface are encoded into
+ * the device tree itself, hence this hook.
+ */
+struct ether_get_mac_address_args {
+	/* This buffer is assumed to be ETHER_ADDR_LEN bytes in size. */
+	uint8_t *	enaddr;		/* OUT */
+};
+
+union ether_get_mac_address_binding {
+	struct device_call_generic generic;
+	struct {
+		const char *name;
+		struct ether_get_mac_address_args *args;
+	} binding;
+};
+
+#define ETHER_GET_MAC_ADDRESS_STR "ether-get-mac-address"
+
+#define ETHER_GET_MAC_ADDRESS(_args_) \
+	&((const union ether_get_mac_address_binding){ \
+		.binding.name = "ether-get-mac-address", \
+		.binding.args = (_args_), \
+	})
+
+#endif /* _ETHER_CALLS_H_ */

sys/net/if_ethersubr.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: if_ethersubr.c,v 1.332 2025/10/04 04:44:19 thorpej Exp $	*/
+/*	$NetBSD: if_ethersubr.c,v 1.333 2025/10/12 23:41:09 thorpej Exp $	*/
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -61,7 +61,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_ethersubr.c,v 1.332 2025/10/04 04:44:19 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_ethersubr.c,v 1.333 2025/10/12 23:41:09 thorpej Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -113,6 +113,7 @@ __KERNEL_RCSID(0, "$NetBSD: if_ethersubr.c,v 1.332 2025/10/04 04:44:19 thorpej E
 
 #include <net/if_ether.h>
 #include <net/if_vlanvar.h>
+#include <net/ether_calls.h>
 
 #if NPPPOE > 0
 #include <net/if_pppoe.h>
@@ -192,6 +193,19 @@ static pktq_rps_hash_func_t ether_pktq_rps_hash_p;
 bool
 ether_getaddr(device_t dev, uint8_t enaddr[ETHER_ADDR_LEN])
 {
+	/*
+	 * First check the platform device tree; it may have specific
+	 * rules about how Ethernet addresses are assigned, separate
+	 * from properties associated with a given device.
+	 */
+	struct ether_get_mac_address_args args = {
+		.enaddr = enaddr,
+	};
+	if (device_call(dev, ETHER_GET_MAC_ADDRESS(&args)) == 0) {
+		/* Got it from the platform device tree. */
+		return true;
+	}
+
 	/*
 	 * Check first for the "mac-address" property.  The bindings
 	 * say that this would be used only if it is different then the