minix/man/man8/installboot.8

.TH INSTALLBOOT 8
.SH NAME
installboot \- make a device bootable
.SH SYNOPSIS
.B installboot \-i(mage)
.I image
.RI [ label :] kernel
.IR "mm fs" " ... " init
.br
.B installboot \-(e)x(tract)
.I image
.br
.B installboot \-d(evice)
.I device bootblock boot
.RI [[ label :] image
\&...]
.br
.B installboot \-b(oot)
.I device bootblock boot
.RI [ label :] image
\&...
.br
.B installboot \-m(aster)
.I device masterboot
.RI [ keys " [" logical ]]
.SH DESCRIPTION
.de SP
.if t .sp 0.4
.if n .sp
..
.B Installboot
may be used to make a device bootable by constructing a kernel image and
installing bootstrap code into the boot block of a MINIX 3 file system.  To
understand how this can be done one first has to know what happens when a
PC is booted.
.PP
When the power is turned on the typical PC will try to read the first sector
from the first floppy disk or from the first hard disk into memory and execute
it.  The code obtained from the hard disk (from the so-called master boot
sector) will immediately replace itself by the code found in the first sector
of the active partition.  Thus the PC is now executing the bootstrap code found
in the first sector of /dev/fd0, /dev/c0d0p0, /dev/c0d0p1, /dev/c0d0p2, or
/dev/c0d0p3 (assuming the boot disk is attached to controller 0.)
The bootstrap will locate the operating system on the device it itself was
loaded from, load it, and execute it.
.PP
To make a MINIX 3 file system
.B /dev/fd0
mounted on
.B /mnt
bootable, enter the following:
.SP
.RS
.ft B
cp /usr/mdec/boot /mnt/boot
.SP
installboot \-i /mnt/minix kernel mm fs init
.SP
installboot \-d /dev/fd0 /usr/mdec/bootblock boot
.ft P
.RE
.PP
The "boot" program in the example is named the "Boot Monitor".  It is loaded
by the bootblock code placed in the boot sector of /dev/fd0 and it will take
care of loading the kernel image "minix" from the root directory of the
file system.  See
.BR monitor (8)
for a description of the Boot Monitor.  Note that
.B boot
is a name in the file system on
.B /dev/fd0
in this example, the same file as
.BR /mnt/boot .
Making
.B /mnt/minix
is normally not necessary, there is usually a kernel image in the
.B tools
directory.
.SH OPTIONS
.B \-i(mage)
.I image
.RI [ label :] kernel
.IR "mm fs" " ... " init
.RS
The
.B \-image
option (or the
.B \-i
shorthand) combines the executable files needed to run MINIX 3 in one file.
Only the names and a few zero bytes are inserted into the image.  The name
is for identification and the zeros are used to pad separate pieces to
sector boundaries for fast loading.
.SP
An executable may be prefixed by a label.  The Monitor may be instructed to
load processes by label.  So more than one kernel process may be included in
the image, each with a different winchester driver for instance.  So if you
have compiled two different kernels with an AT or XT driver then
.SP
.RS
.BI "installboot \-i" " image AT:at_kernel XT:xt_kernel mm fs init"
.RE
.SP
will make an image with two different labeled kernels and one
unlabeled set of the other binaries.
.RE
.PP
.B \-(e)x(tract)
.I image
.RS
Extract the binaries from
.I image
under the names stored in the image.  (The name includes the optional label.)
.RE
.PP
.B \-d(evice)
.I device bootblock boot
.RI [[ label :] image
\&...]
.RS
Installs
.I bootblock
in the boot sector of
.I device
together with the disk addresses to
.IR boot .
These disk addresses are needed to load
.I boot
from the file system at boot time.  The argument
.I boot
is first searched in the file system on
.IR device .
If it is not found then it is read as a normal file and added at the end of
the file system.  The file system should be smaller than the device it is on
to allow this.  Any extra images are also added to the end as described
under
.BR \-boot .
(Make sure you understand all this.)
.SP
The device need not be mounted when
.B installboot
is run, nor does it matter if it is.
.SP
.B Installboot
needs to be run again if
.I boot
is rewritten, because it will then occupy a new place on the disk.
.SP
Old boot parameters are kept if there are no images added.
.RE
.PP
.B \-b(oot)
.I device bootblock boot
.RI [ label :] image
\&...
.RS
This option fills a blank floppy in
.I device
with boot code and kernel images.  This "boot disk" does not have a root
file system, only the Boot Monitor and MINIX 3 kernels.  The boot parameters
sector is filled with code that enables menu options for selecting an
image.  After loading an image, the Monitor will ask you to insert a root
file system diskette before starting MINIX 3.
.SP
The labels used on the images should match those on the executables used
inside the image.  You can put a comma separated list of labels on an image
for each label used within the image.  For the image created earlier one
would create a boot floppy like this:
.SP
.RS
.nf
.BI "installboot \-b /dev/fd0 bootblock boot" " AT,XT:image"
.fi
.RE
.SP
If a label-list is omitted on an image, then that image will be selected by
default.  (Like in the normal one image, no labels case.)
.SP
Note that
.B \-device
and
.B \-boot
together allow you to make a boot floppy with or without a root file system.
With the boot code in the file system, attached to the end of it, or after
the boot block.  And with one or more kernel images in the file system or
at the end of the device.  Somewhat confusing.
.RE
.PP
.B \-m(aster)
.I device masterboot
.RI [ keys " [" logical ]]
.RS
This option installs the
.I masterboot
program into the boot sector of the given device.  If another device is
given instead of
.I masterboot
then its bootstrap code is copied to
.IR device .
The master bootstrap on a hard disk boots the active partition on that disk
at boot time.  The MS-DOS fdisk command normally puts a master bootstrap on
the hard disk.  MINIX 3 has two bootstraps that can be used as a master
bootstrap,
.B masterboot
and
.BR jumpboot.
.SP
.B Masterboot
is a fairly normal master bootstrap that works as follows:
.RS
.SP
If installed on a hard disk then it will load the bootstrap of the active
partition and run it.
.B Masterboot
can be put in the first sector of a hard disk to boot the active partition,
or in the first sector of a MINIX 3 partition to boot the active subpartition.
.SP
If installed on a MINIX 3 floppy then it will try to boot the next floppy or
the first hard disk.  Ideal for floppies with just data on it, they will no
longer obstruct the boot process if left in the drive.  Also a very useful
trick to boot from floppy drive 1.
.RE
.SP
The other bootstrap named
.B jumpboot
is used for the weird cases:
.SP
.RS
If your default operating system is installed on another disk then
.B jumpboot
can be installed on the first disk and instructed to boot the disk,
partition or subpartition that must be booted by default.
.SP
If one of your operating systems insists on being active when booted then use
.B jumpboot
to ignore the active flag and boot your preferred O.S. instead.  The Boot
Monitor's "\fBboot\ \(**\fP" trick to activate the partition to boot is
useful here.
.SP
To boot a logical partition within an extended partition.  Note that you can
put
.B jumpboot
in the first sector of the extended partition in this case, with the
extended partition marked active.
.SP
If you hold down the ALT key while
.B jumpboot
is being executed, then you can type the disk, partition or subpartition
you want to boot as one to three digits followed by typing ENTER.
.RE
.SP
.B Jumpboot
can be programmed to boot a certain partition with the
.I keys
argument and optionally also the
.I logical
argument.
.I Keys
are one to three digits naming the disk, partition or subpartition.  If the
device to boot is
.BR /dev/c0d1p3s0 ,
then
.I keys
is
.BR 130 .
These are the same three digits you can type manually if you hold down ALT
at boot.  To program
.B jumpboot
to boot a logical partition within an extended partition, let
.I keys
be just a disk number, and specify
.I logical
as the name of the logical partition on that disk that is to be booted.
(Actually
.I logical
can be any device name, but this form should be avoided because it offers
less checking to see if the device is still there after a disk
rearrangement.)
.SP
A backup copy of the current master bootstrap (including the partition
table) can be made with:
.RS
.SP
dd if=\fIdevice\fP of=\fIbackup-file\fP count=1
.SP
.RE
A simple 'cp \fIbackup-file\fP \fIdevice\fP' will put it back.  You can
also use
.B fdisk /mbr
under MS-DOS 5.0 (or newer) to restore the master bootstrap.
.RE
.RE
.SH FILES
.TP 25
.B /usr/mdec/bootblock
MINIX 3 bootstrap for the Minix root device.  To be placed in the boot sector.
.TP
.B /usr/mdec/boot
MINIX 3 Boot Monitor.  Can usually be found in the root directory of a bootable
device.
.TP
.B /usr/mdec/masterboot
Master bootstrap.  Can be placed in the first sector of a disk to select the
active partition.  In a MINIX 3 primary partition it selects the active
subpartition.
.TP
.B /usr/mdec/jumpboot
Special "boot this" bootstrap.
.SH "SEE ALSO"
.BR part (8),
.BR monitor (8).
.SH DIAGNOSTICS
.I File
is not an executable
.RS
What you think is boot code or part of the kernel isn't.
.RE
.SP
.I Program
will crash, text/data segment larger then 64K
.RS
One of the 16-bit programs added to an image has a text or data segment
that is larger than 64K.  You probably enabled too many drivers, or
configured too many buffers.
.RE
.SP
.I File
can't be attached to
.I device
.RS
You are trying to put the boot monitor or an image after a file system, but
there is no or not enough space.  Did you specify the full path of the
monitor instead of just "boot"?
.RE
.SP
.I Device
is not a MINIX 3 file system
.RS
You are using
.B \-device
on a device that doesn't contain a file system.  Maybe you specified the
wrong device, maybe you should make a file system, or maybe you should use
.BR \-boot .
.RE
.SP
.I Device
contains a file system
.RS
You are about to destroy a file system with
.BR \-boot .
Maybe you meant to use
.BR \-device ?
You have 10 seconds to make up your mind...
.RE
.SP
.I File
is too big
.RS
Several types of messages like these will tell you that
.I file
can't be installed in a boot sector, or that there is no room to add some
parameters, etc.  Is
.I file
really a bootstrap?
.RE
.SS "Bootstrap errors"
Read error
.RS
A read error trying to get the next bit of boot code.  You may even get the
BIOS error code in hex.  Either the device has a bad block, or jumpboot is
told to read a nonexistent disk.
.RE
.SP
No active partition
.RS
None of the partitions in a partition table is marked active.
.RE
.SP
Not bootable
.RS
Partition does not exist (jumpboot), or it's bootstrap isn't executable.
.RE
.SH NOTES
The MINIX 3 bootstraps can boot beyond the 8G disk size limit if the BIOS
supports the IBM/MS INT 13 Extensions.  Alas only Minix-vmd can make use of
this, standard MINIX 3 has a 4G disk size limit.
.SH BUGS
It has four more options than the SunOS installboot program it is modeled
after.
.PP
The bootblock code has been crunched to such ugliness that you can use it
to scare little kids out of your garden.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
.\"
.\" $PchId: installboot.8,v 1.7 2000/08/13 22:09:31 philip Exp $