path: root/sys/arch/i386/stand/boot/boot.8

.\"	$OpenBSD: boot.8,v 1.4 1997/09/06 00:37:34 deraadt Exp $
.\"
.\" Copyright (c) 1997 Michael Shalayeff
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\"    notice, this list of conditions and the following disclaimer in the
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.\"    must display the following acknowledgement:
.\"	This product includes software developed by Michael Shalayeff.
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.Dd September 1, 1997
.Dt BOOT 8 i386
.Os
.Sh NAME
.Nm boot
.Nd
secondary system bootstrap program
.Sh DESCRIPTION
The main purpose of this program is to load the system kernel, dealing with
all the bugs and bottlenecks of the PC BIOS ``architecture'' and philosophy.
.Pp
As described in
.Xr boot_i386 8
this program is loaded by the
.Xr biosboot 8
primary bootstrap loader and will give you a convinient way to load the kernel.
This program acts as an enhanced boot monitor or ROM for PC systems, providing
a buffer or common interface for the kernel to start from.
.Pp
Basic operations include:
.Bl -bullet -compact
.It
Detecting and switching between multiple console types.
.It
Loading kernels from any device supported by your system BIOS.
.It
Loading kernels compressed by
.Xr gzip 1
program or
.Xr zlib 3
routines.
.It
Passing system parameters queried from the BIOS to the kernel.
.It
Providing an interactive command line.
.El
.Pp
The sequences of its operation consist of initialization
followed by an interactive command line. While at the command
line you have a timeout of 5 seconds (initially, then increasing
by one second on every subsequent kernel load failure)
to type any commands, if needed. Upon timeout expiration, the
kernel will be loaded according to the current variables
settings (See the
.Nm set
command for details).
The sequence of
.Nm
operations is as follows:
.Bl -enum
.It
Setup protected mode involving IDT setup for processor exceptions to
be caught and reported, and setup a simple real-mode BIOS interface.
.It
Probe for console devices, which includes the PC VGA+Keyboard console
and up to four serial consoles connected to the serial ports.
Corresponding messages report about the found devices to the default
console device, which is pc0, if present.
.It
Probe for memory. Conventional memory is probed by quering the BIOS.
Extended memory is probed by running through the memory probing
for present pages, which eliminates the BIOS restriction of 64M of memory.
All the memory found is reported to the default console device.
.It
Probe for APM support in the BIOS. Message printed if support is present.
.It
Open, and if successfull process
.Pa /etc/boot.conf
file on the same filesystem
.Nm
was loaded from. This file may contain any commands
.Nm
accepts at the interactive prompt.
Usually they are commands that change boot parameters according to your
environment, although default values are usable in most cases.
.It
The header line
.Pp
.Dl OpenBSD BOOT [x.xx]
.Pp
is displayed to the active console, where
.Ar x.xx
is a version number of the
.Nm
program, followed by the
.Pp
.Dl boot>
.Pp
prompt, which means you are in the interactive mode and may enter
commands. If you do not,
.Nm
will proceed loading kernel with the current parameters after the
timeout period has expired.
.El
.Sh COMMANDS
The following commands are accepted at the
.Nm
prompt:
.Bl -tag -width machine_diskinfo_boot_
.It boot Op Ar image Op Fl abcds
Boots kernel image specified by the
.Ar image
with options if any. Image specification consists of a pair
.Nm device : Nm filename ,
either of each maybe omitted (':' is not needed if both)
in which case values from
.Nm
variables will be used.
.It echo
Prints it's arguments.
.It help
Prints a list of available commands and machine dependant
commands, if any.
.It machine Op Ar subcommand
Issues machine-dependant commands. These are defined for i386 architecture:
.Bl -tag -width diskinfo_
.It diskinfo
Prints list of hard disks installed on your system including:
BIOS device number, and the BIOS geometry.
.El
.It ls Op Ar directory
Prints contents of the specified
.Ar directory
in long format including: attributes and file type, owner, group,
size, filename.
.It regs
Prints contents of processor registers, if defind for this architecture.
.It reboot
Reboots machine by initiating a warm boot procedure.
.It set Op varname Op value
If invoked without arguments will print a list of variables with values.
If
.Ar varname
and
.Ar value
present will set variable with that name to the given value.
Variables include:
.Pp
.Bl -tag -compact -width boothow
.It addr
Address at wich to load the kernel.
.It howto
Options to pass to the loaded kernel.
.It debug
Debug flag if
.Nm
was compiled with DEBUG defined.
.It device
Boot device name (ie fd0a, sd0a).
.It tty
Active console device name.
.It image
File name containing the kernel image.
.El
.It time
Displays system time and date.
.El
.Sh FILES
.Bl -tag -width /usr/mdec/biosbootxx -compact
.It Pa /usr/mdec/biosboot
primary bootstrap
.It Pa /boot
system bootstrap
.It Pa /etc/boot.conf
system bootstrap's startup file
.It Pa /bsd
system code
.El
.Sh SEE ALSO
.Xr boot_i386 8 ,
.Xr fdisk 8 ,
.Xr installboot 8 ,
.Xr boot 8 ,
.Xr gzip 1 ,
.%B http://quest.jpl.nasa.gov/zlib/ .
.Sh BUGS
Well, nobody is perfect.
.Sh HISTORY
This program was written by Michael Shalayeff for
.Ox 2.1 .