FreeBSD Developers' Handbook
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9.2 Overview

A computer running FreeBSD can boot by several methods, although the most common method, booting from a harddisk where the OS is installed, will be discussed here. The boot process is divided into several steps:

BIOS POST
boot0 stage
boot2 stage
loader stage
kernel initialization

The boot0 and boot2 stages are also referred to as bootstrap stages 1 and 2 in boot(8) as the first steps in FreeBSD's 3-stage bootstrapping procedure. Various information is printed on the screen at each stage, so you may visually recognize them using the table that follows. Please note that the actual data may differ from machine to machine:

may vary	BIOS (firmware) messages
F1 FreeBSD F2 BSD F5 Disk 2	`boot0`
>>FreeBSD/i386 BOOT Default: 1:ad(1,a)/boot/loader boot:	`boot2`^a
BTX loader 1.0 BTX version is 1.01 BIOS drive A: is disk0 BIOS drive C: is disk1 BIOS 639kB/64512kB available memory FreeBSD/i386 bootstrap loader, Revision 0.8 Console internal video/keyboard (jkh@bento.freebsd.org, Mon Nov 20 11:41:23 GMT 2000) /kernel text=0x1234 data=0x2345 syms=[0x4+0x3456] Hit [Enter] to boot immediately, or any other key for command prompt Booting [kernel] in 9 seconds..._	loader
Copyright (c) 1992-2002 The FreeBSD Project. Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994 The Regents of the University of California. All rights reserved. FreeBSD 4.6-RC #0: Sat May 4 22:49:02 GMT 2002 devnull@kukas:/usr/obj/usr/src/sys/DEVNULL Timecounter "i8254" frequency 1193182 Hz	kernel
Notes: a. This prompt will appear if the user presses a key just after selecting an OS to boot at the `boot0` stage.

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