.\"	$OpenBSD: installboot.8,v 1.28 2007/05/31 19:20:03 jmc Exp $
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.\" Copyright (c) 1997 Michael Shalayeff
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.Dd $Mdocdate: May 31 2007 $
.Dt INSTALLBOOT 8 i386
.Os
.Sh NAME
.Nm installboot
.Nd installs a bootstrap on an FFS disk or partition
.Sh SYNOPSIS
.Nm installboot
.Op Fl nv
.Ar boot
.Ar biosboot
.Ar disk
.Sh DESCRIPTION
.Nm
is used to install a
.Dq first-stage
boot program into the boot area of an FFS disk partition.
It inserts the block number and offset of the inode of
the second-stage boot program
.Xr boot 8
so that the
.Xr biosboot 8
program can load it.
Various filesystem parameters are also patched into the boot block.
.Pp
The options are as follows:
.Bl -tag -width flag_opt
.It Fl n
Do not actually write anything on the disk.
.It Fl v
Be verbose, printing out the data that are stored in
.Ar biosboot
along with lots of other information.
.El
.Pp
The arguments are:
.Bl -tag -width biosboot
.It Ar boot
The name of the second-stage boot program in the mounted file system
where the first-stage boot program is to be installed.
This should be a full pathname.
.It Ar biosboot
The name of the prototype file for the first stage boot program,
usually
.Pa /usr/mdec/biosboot .
.It Ar disk
The name of the disk containing the partition in which the second-stage
boot program resides and the first-stage boot program is to be installed.
This can either be specified in short form (e.g.,
.Sq sd0
or
.Sq wd0 ) ,
or as the explicit device node, such as
.Pa /dev/rsd0c
or
.Pa /dev/rwd0c .
.Pp
Note that you must be in single-user mode or have your kernel in
insecure mode (see the
.Xr sysctl 8
.Va kern.securelevel
variable or
.Pa /etc/rc.securelevel )
to enable access to the raw partition of a mounted disk.
.Pp
The
.Sq c
partition is always used to represent the
.Dq entire
disk on i386.
.El
.Sh EXAMPLES
The typical use is
.Bd -literal -offset indent
# cp /usr/mdec/boot /boot
# /usr/mdec/installboot -n -v /boot /usr/mdec/biosboot sd0
.Ed
.Pp
And if the information supplied looks right, run the above without the
.Fl n
flag.
If you are upgrading an old system, you may need to perform
some additional steps first.
For example:
.Bd -literal -offset indent
boot the floppy.fs filesystem floppy
# fsck /dev/rsd0a
# mount /dev/sd0a /mnt
# cp /usr/mdec/boot /mnt/boot
# /usr/mdec/installboot -v /mnt/boot /usr/mdec/biosboot sd0
.Ed
.Sh SEE ALSO
.Xr biosboot 8 ,
.Xr boot 8 ,
.Xr disklabel 8 ,
.Xr fdisk 8 ,
.Xr init 8
.Sh CAVEATS
The disklabel
.Va d_type
field must be set to a value other than
.Dq unknown .
.Pp
.Pa /boot
must be on the drive/partition specified by
.Pa disk ;
you cannot perform cross-device
.Nm Ns s .