1.\" Copyright (c) 1991 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" This code is derived from software written and contributed 5.\" to Berkeley by William Jolitz. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)reboot_i386.8 1.2 (Berkeley) 4/25/91 36.\" 37.Dd April 25, 1991 38.Dt REBOOT 8 39.Os 40.Sh NAME 41.Nm reboot 42.Nd 43.Tn UNIX 44bootstrapping procedures 45.Sh SYNOPSIS 46.Nm reboot 47.Op Fl n 48.Op Fl q 49.Sh DESCRIPTION 50.Tn UNIX , 51an ordinary executable file, 52is placed into memory by bootstrap at location absolute zero, and 53entered at the executable's entry point 54.Pq Va a_entry . 55Upon startup, the system reorganizes memory to suit the needs of 56the hardware configuration found, thus it is not designed to 57be restartable without being reloaded on reboot. 58Each time it is to be bootstrapped, it must be reloaded, usually from 59a disk file. 60.Pp 61.Sy Rebooting a running system . 62When a 63.Tn UNIX 64is running and a reboot is desired, 65.Xr shutdown 8 66is normally used. 67If there are no users then 68.Nm reboot 69can be used. 70Reboot causes the disks to be synced and allows the system 71to perform other shutdown activities such as resynchronizing 72hardware time-of-day clocks. 73A multi-user reboot (as described below) is then initiated. 74This causes a system to be 75booted and an automatic disk check to be performed. If all this succeeds 76without incident, the system is then brought up for many users. 77.Pp 78Options to reboot are: 79.Bl -tag -width indent 80.It Fl n 81option avoids the sync. It can be used if a disk or the processor 82is on fire. 83.It Fl q 84reboots quickly and ungracefully, without shutting down running 85processes first. 86.El 87.Pp 88.Nm Reboot 89normally logs the reboot using 90.Xr syslog 8 91and places a shutdown record in the login accounting file 92.Pa /var/log/wtmp . 93These actions are inhibited if the 94.Fl n 95or 96.Fl q 97options are present. 98.Pp 99.Sy Power fail and crash recovery. 100Normally, the system will reboot itself at power-up or after crashes. 101An automatic consistency check of the file systems will be performed 102as described in 103.Xr fsck 8 . 104and unless this fails, the system will resume multi-user operations. 105.Pp 106.Sy Cold starts . 107The 386 108.Tn "PC AT" 109clones attempt to boot the floppy disk drive A (otherwise 110known as drive 0) first, and failing that, attempt to boot the hard disk 111C (otherwise known as hard disk controller 1, drive 0). 112The automatic boot will attempt to load 113.Pa vmunix 114from partition A of 115either the floppy or the hard disk. This boot may be aborted by typing 116any character on the keyboard repeatedly (four or five times at least) 117during the operating system load phase, after which the bootstrap will 118prompt for the file that you wish to load instead. 119.Pp 120One exception to this is the 121.Ql d 122key, which will not abort the load but 123instead silently force the 124.Dv DEBUG 125boot flags. The boot flags for an autoboot 126are 0, and 3 for the successive boot after an aborted autoboot sequence. 127No other provison is made for setting boot flags (yet). 128A specific device or bootstrap file may be used; for example, 129.Pp 130The file specifications used for the boostrap 131when loaded with the 132.Dq askme 133flag 134(e.g. an aborted autoboot) 135are of the form: 136.Pp 137.Dl device unit partition: 138.Pp 139where 140.Ar device 141is the type of the device, assumed to be on the ISA bus, to be searched, 142.Ar unit 143is the unit number of the disk or tape, 144and 145.Ar partition 146is the disk partition or tape file number. 147Normal line editing characters can be used when typing the file specification. 148The following list of supported devices may vary from installation to 149installation: 150.Bd -unfilled -offset indent 151wd ST506, IDE, ESDI, RLL disks on a WD100[2367] or lookalike 152 controller 153fd 5 1/4" or 3 1/2" High density floppies 154.Ed 155.Pp 156For example, 157to boot from a file system which starts at cylinder 0 158of unit 0 of an IDE disk, type 159.Dq Li wd0a:vmunix 160to the boot prompt; 161.Dq Li fd0a:vmunix 162would specify a 3 1/2" floppy drive 0 . 163.Pp 164In an emergency, the bootstrap methods described in the paper 165.%T "Installing and Operating 4.3 BSD-Reno UNIX on the AT/386" 166can be used 167to boot from a distribution tape. 168.Sh FILES 169.Bl -tag -width /vmunixxx -compact 170.It Pa /vmunix 171system code 172.It Pa /boot 173system bootstrap 174.El 175.Sh SEE ALSO 176.Xr crash 8 , 177.Xr disklabel 8 , 178.Xr fsck 8 , 179.Xr halt 8 , 180.Xr init 8 , 181.Xr rc 8 , 182.Xr shutdown 8 , 183.Xr syslogd 8 184.Sh BUGS 185The disklabel format used by this version of 186.Bx 187is quite 188different from that of other architectures. 189