diff --git a/distrib/utils/sysinst/arch/shark/md.c b/distrib/utils/sysinst/arch/shark/md.c
index 00d92471f393..d1a248d207b3 100644
--- a/distrib/utils/sysinst/arch/shark/md.c
+++ b/distrib/utils/sysinst/arch/shark/md.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: md.c,v 1.19 2006/04/05 16:55:07 garbled Exp $	*/
+/*	$NetBSD: md.c,v 1.20 2007/03/12 11:19:37 jmmv Exp $	*/
 
 /*
  * Copyright 1997 Piermont Information Systems Inc.
@@ -53,6 +53,31 @@
 #include "msg_defs.h"
 #include "menu_defs.h"
 
+/*
+ * Clears the disk's first sector by writing all zeros over it.
+ * Returns 0 on success, -1 on failure.  Leaves the disk's path in
+ * the output diskpath buffer for further usage in error messages.
+ */
+static int
+clear_mbr(const char *disk, char *diskpath, size_t diskpathlen)
+{
+	int fd;
+	char sector[512];
+
+	fd = opendisk(disk, O_WRONLY, diskpath, diskpathlen, 0);
+	if (fd < 0)
+		return -1;
+
+	memset(sector, 0, sizeof(sector));
+	if (pwrite(fd, &sector, sizeof(sector), 0) < 0) {
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+	return 0;
+}
+
 int
 md_get_info(void)
 {
@@ -103,6 +128,13 @@ md_get_info(void)
 int
 md_pre_disklabel(void)
 {
+	char diskpath[MAXPATHLEN];
+
+	if (clear_mbr(diskdev, diskpath, sizeof(diskpath)) == -1) {
+		msg_display(MSG_badclearmbr, diskpath);
+		process_menu(MENU_ok, NULL);
+	}
+
 	return 0;
 }
 
@@ -178,5 +210,9 @@ md_init(void)
 int
 md_post_extract(void)
 {
+
+	msg_display(MSG_setbootdevice);
+	process_menu(MENU_ok, NULL);
+
 	return 0;
 }
diff --git a/distrib/utils/sysinst/arch/shark/msg.md.de b/distrib/utils/sysinst/arch/shark/msg.md.de
index dac50098b314..489fe1756f00 100644
--- a/distrib/utils/sysinst/arch/shark/msg.md.de
+++ b/distrib/utils/sysinst/arch/shark/msg.md.de
@@ -1,4 +1,4 @@
-/*	$NetBSD: msg.md.de,v 1.4 2004/10/21 12:14:22 martin Exp $	*/
+/*	$NetBSD: msg.md.de,v 1.5 2007/03/12 11:19:37 jmmv Exp $	*/
 
 /*
  * Copyright 1997 Piermont Information Systems Inc.
@@ -81,3 +81,27 @@ message arm32fspart
 
 message set_kernel_1
 {Kernel (GENERIC)}
+
+message setbootdevice
+{In order to make your system boot automatically from the on-disk file
+system, you need to manually configure OpenFirmware to tell it where to
+load the kernel from.
+
+OpenFirmware can load a NetBSD a.out kernel (sorry, ELF is not supported)
+straight from a FFS partition on the local hard disk.  So, to configure it
+to boot the just-installed kernel, run the following command from
+OpenFirmware's shell:
+
+setenv boot-device disk:\\netbsd.aout
+
+You only need to run this once and only if the 'boot-device' property did
+not already contain the value shown above.
+}
+
+message badclearmbr
+{Failed to clear the disk's first sector.  If OpenFirmware cannot see the
+disk, try to run the following command manually from the installer's shell
+utility:
+
+dd if=/dev/zero of=%s bs=512 count=1
+}
diff --git a/distrib/utils/sysinst/arch/shark/msg.md.en b/distrib/utils/sysinst/arch/shark/msg.md.en
index 50ba650fc885..84a20dde63c5 100644
--- a/distrib/utils/sysinst/arch/shark/msg.md.en
+++ b/distrib/utils/sysinst/arch/shark/msg.md.en
@@ -1,4 +1,4 @@
-/*	$NetBSD: msg.md.en,v 1.6 2003/06/12 11:20:13 dsl Exp $	*/
+/*	$NetBSD: msg.md.en,v 1.7 2007/03/12 11:19:37 jmmv Exp $	*/
 
 /*
  * Copyright 1997 Piermont Information Systems Inc.
@@ -77,3 +77,27 @@ message arm32fspart
 
 message set_kernel_1
 {Kernel (GENERIC)}
+
+message setbootdevice
+{In order to make your system boot automatically from the on-disk file
+system, you need to manually configure OpenFirmware to tell it where to
+load the kernel from.
+
+OpenFirmware can load a NetBSD a.out kernel (sorry, ELF is not supported)
+straight from a FFS partition on the local hard disk.  So, to configure it
+to boot the just-installed kernel, run the following command from
+OpenFirmware's shell:
+
+setenv boot-device disk:\\netbsd.aout
+
+You only need to run this once and only if the 'boot-device' property did
+not already contain the value shown above.
+}
+
+message badclearmbr
+{Failed to clear the disk's first sector.  If OpenFirmware cannot see the
+disk, try to run the following command manually from the installer's shell
+utility:
+
+dd if=/dev/zero of=%s bs=512 count=1
+}
diff --git a/distrib/utils/sysinst/arch/shark/msg.md.es b/distrib/utils/sysinst/arch/shark/msg.md.es
index 7f35b303e995..c676efc65ece 100644
--- a/distrib/utils/sysinst/arch/shark/msg.md.es
+++ b/distrib/utils/sysinst/arch/shark/msg.md.es
@@ -1,4 +1,4 @@
-/*	$NetBSD: msg.md.es,v 1.2 2005/08/26 16:32:33 xtraeme Exp $	*/
+/*	$NetBSD: msg.md.es,v 1.3 2007/03/12 11:19:37 jmmv Exp $	*/
 
 /*
  * Copyright 1997 Piermont Information Systems Inc.
@@ -80,3 +80,26 @@ Compensaci
 
 message set_kernel_1
 {Núcleo (GENERIC)}
+
+message setbootdevice
+{Para conseguir que el sistema arranque automaticamente desde el sistema
+de ficheros del disco, necesita configura manualmente OpenFirmware para
+indicarle desde dónde debe cargar el núcleo del sistema.
+
+OpenFirmware puede cargar un núcleo a.out de NetBSD (perdone, pero ELF no está soportado) directamente desde una partición FFS del disco local.  Así que, para
+configurarlo para que arranque desde disco deberá ejecutar manualmente el
+siguiente comando desde la interfaz de OpenFirmware:
+
+setenv boot-device disk:\\netbsd.aout
+
+Sólo tiene que ejecutar esto una vez y sólamente si la propiedad
+'boot-device' no contenía el valor mostrado arriba.
+}
+
+message badclearmbr
+{Ha ocurrido un error al intentar borrar el primer sector del disco.  Si el
+firmware no puede verlo, pruebe a ejecutar el siguiente comando manualmente
+desde la linea de comandos de la utilidad de instalación:
+
+dd if=/dev/zero of=%s bs=512 count=1
+}
diff --git a/distrib/utils/sysinst/arch/shark/msg.md.fr b/distrib/utils/sysinst/arch/shark/msg.md.fr
index acffafb8a00e..d7a11807d553 100644
--- a/distrib/utils/sysinst/arch/shark/msg.md.fr
+++ b/distrib/utils/sysinst/arch/shark/msg.md.fr
@@ -1,4 +1,4 @@
-/*	$NetBSD: msg.md.fr,v 1.6 2003/06/12 11:20:13 dsl Exp $	*/
+/*	$NetBSD: msg.md.fr,v 1.7 2007/03/12 11:19:37 jmmv Exp $	*/
 
 /*
  * Copyright 1997 Piermont Information Systems Inc.
@@ -82,3 +82,26 @@ message arm32fspart
 message set_kernel_1
 {Kernel (GENERIC)}
 
+message setbootdevice
+{In order to make your system boot automatically from the on-disk file
+system, you need to manually configure OpenFirmware to tell it where to
+load the kernel from.
+
+OpenFirmware can load a NetBSD a.out kernel (sorry, ELF is not supported)
+straight from a FFS partition on the local hard disk.  So, to configure it
+to boot the just-installed kernel, run the following command from
+OpenFirmware's shell:
+
+setenv boot-device disk:\\netbsd.aout
+
+You only need to run this once and only if the 'boot-device' property did
+not already contain the value shown above.
+}
+
+message badclearmbr
+{Failed to clear the disk's first sector.  If OpenFirmware cannot see the
+disk, try to run the following command manually from the installer's shell
+utility:
+
+dd if=/dev/zero of=%s bs=512 count=1
+}
diff --git a/distrib/utils/sysinst/arch/shark/msg.md.pl b/distrib/utils/sysinst/arch/shark/msg.md.pl
index 09497e2aa00c..fca5e14d8caa 100644
--- a/distrib/utils/sysinst/arch/shark/msg.md.pl
+++ b/distrib/utils/sysinst/arch/shark/msg.md.pl
@@ -1,4 +1,4 @@
-/*	$NetBSD: msg.md.pl,v 1.5 2003/06/12 11:20:13 dsl Exp $	*/
+/*	$NetBSD: msg.md.pl,v 1.6 2007/03/12 11:19:38 jmmv Exp $	*/
 /* Based on english version: */
 /*	NetBSD: msg.md.en,v 1.2 2002/04/02 17:02:54 thorpej Exp */
 
@@ -80,3 +80,26 @@ message arm32fspart
 message set_kernel_1
 {Kernel (GENERIC)}
 
+message setbootdevice
+{In order to make your system boot automatically from the on-disk file
+system, you need to manually configure OpenFirmware to tell it where to
+load the kernel from.
+
+OpenFirmware can load a NetBSD a.out kernel (sorry, ELF is not supported)
+straight from a FFS partition on the local hard disk.  So, to configure it
+to boot the just-installed kernel, run the following command from
+OpenFirmware's shell:
+
+setenv boot-device disk:\\netbsd.aout
+
+You only need to run this once and only if the 'boot-device' property did
+not already contain the value shown above.
+}
+
+message badclearmbr
+{Failed to clear the disk's first sector.  If OpenFirmware cannot see the
+disk, try to run the following command manually from the installer's shell
+utility:
+
+dd if=/dev/zero of=%s bs=512 count=1
+}