NetBSD/sbin/reboot/reboot_i386.8

.\" Copyright (c) 1991 The Regents of the University of California.
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.\" This code is derived from software written and contributed
.\" to Berkeley by William Jolitz.
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.\"     from: @(#)reboot_i386.8	1.2 (Berkeley) 4/25/91
.\"	$Id: reboot_i386.8,v 1.7 1994/02/14 21:34:43 cgd Exp $
.\"
.Dd April 25, 1991
.Dt REBOOT 8
.Os
.Sh NAME
.Nm reboot
.Nd
.Tn NetBSD
bootstrapping procedures
.Sh SYNOPSIS
.Nm reboot
.Op Fl n
.Op Fl q
.Sh DESCRIPTION
The
.Tn NetBSD
kernel, an ordinary executable file,
is placed into memory by bootstrap at location absolute zero, and
entered at the executable's entry point
.Pq Va a_entry .
Upon startup, the system reorganizes memory to suit the needs of
the hardware configuration found, thus it is not designed to
be restartable without being reloaded on reboot.
Each time it is to be bootstrapped, it must be reloaded, usually from
a disk file.
.Pp
.Sy Rebooting a running system .
When a
.Tn NetBSD
kernel is running and a reboot is desired,
.Xr shutdown 8
is normally used.
If there are no users then
.Nm reboot
can be used.
Reboot causes the disks to be synced and allows the system
to perform other shutdown activities such as resynchronizing
hardware time-of-day clocks.
A multi-user reboot (as described below) is then initiated.
This causes a system to be
booted and an automatic disk check to be performed.  If all this succeeds
without incident, the system is then brought up for many users.
.Pp
Options to reboot are:
.Bl -tag -width indent
.It Fl n
option avoids the sync.  It can be used if a disk or the processor
is on fire. 
.It Fl q
reboots quickly and ungracefully, without shutting down running
processes first.
.El
.Pp
.Nm Reboot
normally logs the reboot using
.Xr syslog 8
and places a shutdown record in the login accounting file
.Pa /var/log/wtmp .
These actions are inhibited if the
.Fl n
or
.Fl q
options are present.
.Pp
.Sy Power fail and crash recovery.
Normally, the system will reboot itself at power-up or after crashes.
An automatic consistency check of the file systems will be performed
as described in
.Xr fsck 8 .
and unless this fails, the system will resume multi-user operations.
.Pp
.Sy Cold  starts .
The 386
.Tn "PC AT"
clones attempt to boot the floppy disk drive A (otherwise
known as drive 0) first, and failing that, attempt to boot the hard disk
C (otherwise known as hard disk controller 1, drive 0).
The automatic boot will attempt to load
.Pa netbsd
from partition A of
either the floppy or the hard disk. This boot may be aborted by typing
any character on the keyboard repeatedly (four or five times at least)
during the operating system load phase, after which the bootstrap will
prompt for the file that you wish to load instead.
.Pp
One exception to this is the
.Ql d
key, which will not abort the load but
instead silently force the
.Dv DEBUG
boot flags. The boot flags for an autoboot
are 0, and 3 for the successive boot after an aborted autoboot sequence.
No other provision is made for setting boot flags (yet).
A specific device or bootstrap file may be used; for example,
.Pp
The file specifications used for the boostrap
when loaded with the
.Dq askme
flag
(e.g. an aborted autoboot)
are of the form:
.Pp
.Dl device unit partition:
.Pp
where
.Ar device
is the type of the device, assumed to be on the ISA bus, to be searched,
.Ar unit
is the unit number of the disk or tape,
and
.Ar partition
is the disk partition or tape file number.
Normal line editing characters can be used when typing the file specification.
The following list of supported devices may vary from installation to
installation:
.Bd -unfilled -offset indent
wd	ST506, IDE, ESDI, RLL disks on a WD100[2367] or lookalike
	controller
fd	5 1/4" or 3 1/2" High density floppies
.Ed
.Pp
For example,
to boot from a file system which starts at cylinder 0
of unit 0 of an IDE disk, type
.Dq Li wd(0,a)/netbsd
to the boot prompt;
.Dq Li fd(0,a)/netbsd
would specify a 3 1/2" floppy drive 0 .
.Sh FILES
.Bl -tag -width /netbsd -compact
.It Pa /netbsd
system code
.\".It Pa /boot
.\"system bootstrap
.El
.Sh SEE ALSO
.Xr crash 8 ,
.Xr disklabel 8 ,
.Xr fsck 8 ,
.Xr halt 8 ,
.Xr init 8 ,
.Xr rc 8 ,
.Xr shutdown 8 ,
.Xr syslogd 8