1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software written and contributed 5.\" to Berkeley by William Jolitz. 6.\" 7.\" %sccs.include.redist.roff% 8.\" 9.\" @(#)boot_i386.8 8.2 (Berkeley) 04/19/94 10.\" 11.Dd 12.Dt BOOT 8 i386 13.Os 14.Sh NAME 15.Nm boot 16.Nd 17system bootstrapping procedures 18.Sh DESCRIPTION 19.Sy Power fail and crash recovery. 20Normally, the system will reboot itself at power-up or after crashes. 21An automatic consistency check of the file systems will be performed, 22and unless this fails, the system will resume multi-user operations. 23.Pp 24.Sy Cold starts. 25The 386 26.Tn "PC AT" 27clones attempt to boot the floppy disk drive A (otherwise known as drive 280) first, and failing that, attempt to boot the hard disk C (otherwise 29known as hard disk controller 1, drive 0). 30The automatic boot will attempt to load 31.Pa vmunix 32from partition A of either the floppy or the hard disk. 33This boot may be aborted by typing any character on the keyboard repeatedly 34(four or five times at least) during the operating system load phase, after 35which the bootstrap will prompt for the file that you wish to load instead. 36.Pp 37One exception to this is the 38.Ql d 39key, which will not abort the load but instead silently force the 40.Dv DEBUG 41boot flags. 42The boot flags for an autoboot are 0, and 3 for the successive boot after 43an aborted autoboot sequence. 44No other provison is made for setting boot flags (yet). 45A specific device or bootstrap file may be used; for example, 46.Pp 47The file specifications used for the boostrap 48when loaded with the 49.Dq askme 50flag 51(e.g. an aborted autoboot) 52are of the form: 53.Pp 54.Dl device unit partition: 55.Pp 56where 57.Ar device 58is the type of the device, assumed to be on the ISA bus, to be searched, 59.Ar unit 60is the unit number of the disk or tape, 61and 62.Ar partition 63is the disk partition or tape file number. 64Normal line editing characters can be used when typing the file specification. 65The following list of supported devices may vary from installation to 66installation: 67.Bd -unfilled -offset indent 68wd ST506, IDE, ESDI, RLL disks on a WD100[2367] or lookalike 69 controller 70fd 5 1/4" or 3 1/2" High density floppies 71.Ed 72.Pp 73For example, 74to boot from a file system which starts at cylinder 0 75of unit 0 of an IDE disk, type 76.Dq Li wd0a:vmunix 77to the boot prompt; 78.Dq Li fd0a:vmunix 79would specify a 3 1/2" floppy drive 0 . 80.Pp 81In an emergency, the bootstrap methods described in the paper 82.%T "Installing and Operating 4.3 BSD-Reno UNIX on the AT/386" 83can be used 84to boot from a distribution tape. 85.Sh FILES 86.Bl -tag -width /vmunixxx -compact 87.It Pa /vmunix 88system code 89.It Pa /boot 90system bootstrap 91.El 92.Sh SEE ALSO 93.Xr halt 8 , 94.Xr reboot 8 , 95.Xr shutdown 8 96.Sh BUGS 97The disklabel format used by this version of 98.Bx 99is quite 100different from that of other architectures. 101