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215 lines
6.1 KiB
Groff
215 lines
6.1 KiB
Groff
.\" Copyright (c) 1999 Robert Nordier
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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.\" OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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.\" OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 13, 2009
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.Dt BOOT0CFG 8
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.Os
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.Sh NAME
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.Nm boot0cfg
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.Nd boot manager installation/configuration utility
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.Sh SYNOPSIS
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.Nm
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.Op Fl Bv
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.Op Fl b Ar boot0
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.Op Fl d Ar drive
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.Op Fl e Ar bell character
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.Op Fl f Ar file
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.Op Fl i Ar volume-id
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.Op Fl m Ar mask
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.Op Fl o Ar options
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.Op Fl s Ar slice
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.Op Fl t Ar ticks
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.Ar disk
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.Sh DESCRIPTION
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The
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.Fx
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.Sq boot0
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boot manager permits the operator to select from which disk and
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slice an i386 machine (PC) is booted.
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.Pp
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Note that what are referred to here as
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.Dq slices
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are typically called
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.Dq partitions
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in
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.No non- Ns Bx
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documentation relating to the PC.
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Typically, only non-removable disks are sliced.
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.Pp
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The
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.Nm
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utility optionally installs the
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.Sq boot0
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boot manager on the specified
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.Ar disk ;
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and allows various operational parameters to be configured.
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.Pp
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On PCs, a boot manager typically occupies sector 0 of a disk, which is
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known as the Master Boot Record (MBR).
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The MBR contains both code (to which control is passed by the PC BIOS)
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and data (an embedded table of defined slices).
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.Pp
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The options are:
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.Bl -tag -width indent
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.It Fl B
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Install the
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.Sq boot0
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boot manager.
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This option causes MBR code to be replaced, without
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affecting the embedded slice table.
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.It Fl b Ar boot0
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Specify which
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.Sq boot0
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image to use.
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The default is
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.Pa /boot/boot0
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which will use the video card as output, alternatively
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.Pa /boot/boot0sio
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can be used for output to the COM1 port.
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(Be aware that nothing will be output to the COM1 port unless the
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modem signals DSR and CTS are active.)
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.It Fl d Ar drive
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Specify the drive number used by the PC BIOS in referencing the drive
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which contains the specified
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.Ar disk .
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Typically this will be 0x80 for the first hard drive, 0x81 for the
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second hard drive, and so on; however any integer between 0 and 0xff
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is acceptable here.
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.It Fl e Ar bell character
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Set the character to be printed in case of input error.
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.It Fl f Ar file
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Specify that a backup copy of the preexisting MBR should be written to
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.Ar file .
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This file is created if it does not exist, and replaced if it does.
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.It Fl i Ar volume-id
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Specifies a volume-id (in the form XXXX-XXXX) to be saved at location
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0x1b8 in the MBR. This information is sometimes used by NT, XP and Vista
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to identify the disk drive. The option is only compatible with version 2.00
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of the 512-byte boot block.
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.It Fl m Ar mask
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Specify slices to be enabled/disabled, where
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.Ar mask
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is an integer between 0 (no slices enabled) and 0xf (all four slices
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enabled).
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.It Fl o Ar options
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A comma-separated string of any of the following options may be
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specified (with
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.Dq no
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prepended as necessary):
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.Bl -tag -width indent
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.It packet
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Use the disk packet (BIOS INT 0x13 extensions) interface,
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as opposed to the legacy (CHS) interface, when doing disk I/O.
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This allows booting above cylinder 1023, but requires specific
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BIOS support.
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The default is
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.Sq packet .
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.It setdrv
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Forces the drive containing the disk to be referenced using drive
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number definable by means of the -d option.
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The default is
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.Sq nosetdrv .
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.It update
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Allow the MBR to be updated by the boot manager.
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(The MBR may be updated to flag slices as
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.Sq active ,
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and to save slice selection information.)
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This is the default; a
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.Sq noupdate
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option causes the MBR to be treated as read-only.
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.El
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.It Fl s Ar slice
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Set the default boot selection to
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.Ar slice .
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Values between 1 and 4 refer to slices; a value of 5 refers to the
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option of booting from a second disk.
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.It Fl t Ar ticks
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Set the timeout value to
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.Ar ticks .
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(There are approximately 18.2 ticks per second.)
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.It Fl v
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Verbose: display information about the slices defined, etc.
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.El
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.Sh NOTE
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Protection mechanisms in the
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.Xr geom 4
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subsystem might prevent
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.Nm
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from being able to update the MBR on a mounted disk.
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Instructions for temporarily disabling these protection mechanisms
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can be found in the
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.Xr geom 4
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manpage. Specifically, do a
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.Pp
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.Dl sysctl kern.geom.debugflags=0x10
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.Pp
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to allow writing to the MBR, and restore it to 0 afterwards.
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.Pp
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.Sh FILES
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.Bl -tag -width /boot/boot0sio -compact
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.It Pa /boot/boot0
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The default
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.Sq boot0
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image
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.It Pa /boot/boot0sio
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Image for serial consoles (COM1,9600,8,N,1,MODEM)
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.El
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.Sh EXIT STATUS
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.Ex -std
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.Sh EXAMPLES
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To boot slice 2 on the next boot:
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.Pp
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.Dl "boot0cfg -s 2 ad0"
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.Pp
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To enable just slices 1 and 2 in the menu:
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.Pp
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.Dl "boot0cfg -m 0x3 ad0"
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.Pp
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To go back to non-interactive booting, use
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.Xr fdisk 8
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to install the default MBR:
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.Pp
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.Dl "fdisk -B ad0"
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.Pp
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.Sh SEE ALSO
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.Xr geom 4 ,
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.Xr boot 8 ,
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.Xr fdisk 8
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.Sh AUTHORS
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.An Robert Nordier Aq rnordier@FreeBSD.org .
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.Sh BUGS
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Use of the
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.Sq packet
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option may cause
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.Sq boot0
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to fail, depending on the nature of BIOS support.
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.Pp
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Use of the
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.Sq setdrv
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option with an incorrect -d operand may cause the boot0 code
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to write the MBR to the wrong disk, thus trashing its previous
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content. Be careful.
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