.\"	$NetBSD: boot.8,v 1.16 2017/02/18 21:47:11 wiz Exp $
.\"
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.\"     @(#)boot_i386.8	8.2 (Berkeley) 4/19/94
.\"
.Dd August 16, 2014
.Dt BOOT 8
.Os
.Sh NAME
.Nm boot
.Nd
system bootstrapping procedures
.Sh DESCRIPTION
This document provides information on using common features in the
.Nx
boot loader.
Additional information may be found in
architecture-specific
.Xr boot 8
manual pages.
.Ss Boot Protocol
In the native
.Nx
boot protocol, options are passed from the boot loader
to the kernel via flag bits in the
.Va boothowto
variable (see
.Xr boothowto 9 ) .
Some boot loaders may also support other boot protocols.
.Ss Menu
Some boot loaders may present a menu, which may be configured via
.Xr boot.cfg 5 .
.Ss Interactive mode
In interactive mode, the boot loader will present a prompt, allowing
input of these commands:
.\" NOTE: much of this text is duplicated in architecture-specific
.\" man pages (man8/man8.*/*boot*.8);
.\" please try to keep all relevant files synchronized.
.Bl -tag -width 04n -offset 04n
.It Ic boot Oo Va device : Oc Ns Oo Va filename Oc Oo Fl 1234abcdmqsvxz Oc
The default
.Va device
will be set to the disk that the boot loader was
loaded from.
To boot from an alternate disk, the full name of the device should
be given at the prompt.
.Va device
is of the form
.Xo Va xd
.Op Va N Ns Op Va x
.Xc
where
.Va xd
is the device from which to boot,
.Va N
is the unit number, and
.Va x
is the partition letter.
.Pp
The following list of supported devices may vary from installation to
installation:
.Pp
.Bl -hang -compact
.It hd
Hard disks.
.It fd
Floppy drives.
.El
.Pp
The default
.Va filename
is
.Pa netbsd ;
if the boot loader fails to successfully
open that image, it then tries
.Pa netbsd.gz
(expected to be a kernel image compressed by gzip), followed by
.Pa netbsd.old ,
.Pa netbsd.old.gz ,
.Pa onetbsd ,
and finally
.Pa onetbsd.gz .
Alternate system images can be loaded by just specifying the name of the image.
.Pp
Options are:
.Bl -tag -width xxx
.It Fl 1
Sets the machine-dependent flag
.Sy RB_MD1
in
.Va boothowto .
.It Fl 2
Sets the machine-dependent flag
.Sy RB_MD2
in
.Va boothowto .
.It Fl 3
Sets the machine-dependent flag
.Sy RB_MD3
in
.Va boothowto .
.It Fl 4
Sets the machine-dependent flag
.Sy RB_MD4
in
.Va boothowto .
.It Fl a
Sets the
.Sy RB_ASKNAME
flag in
.Va boothowto .
This causes the kernel to prompt for the root file system device,
the system crash dump device, and the path to
.Xr init 8 .
.It Fl b
Sets the
.Sy RB_HALT
flag in
.Va boothowto .
This causes subsequent reboot attempts to halt instead of rebooting.
.It Fl c
Sets the
.Sy RB_USERCONF
flag in
.Va boothowto .
This causes the kernel to enter the
.Xr userconf 4
device configuration manager as soon as possible during the boot.
.Xr userconf 4
allows devices to be enabled or disabled, and allows device locators
(such as hardware addresses or bus numbers)
to be modified before the kernel attempts to attach the devices.
.It Fl d
Sets the
.Sy RB_KDB
flag in
.Va boothowto .
Requests the kernel to enter debug mode, in which it
waits for a connection from a kernel debugger; see
.Xr ddb 4 .
.It Fl m
Sets the
.Sy RB_MINIROOT
flag in
.Va boothowto .
Informs the kernel that a mini-root file system is present in memory.
.It Fl q
Sets the
.Sy AB_QUIET
flag in
.Va boothowto .
Boot the system in quiet mode.
.It Fl s
Sets the
.Sy RB_SINGLE
flag in
.Va boothowto .
Boot the system in single-user mode.
.It Fl v
Sets the
.Sy AB_VERBOSE
flag in
.Va boothowto .
Boot the system in verbose mode.
.It Fl x
Sets the
.Sy AB_DEBUG
flag in
.Va boothowto .
Boot the system with debug messages enabled.
.It Fl z
Sets the
.Sy AB_SILENT
flag in
.Va boothowto .
Boot the system in silent mode.
.El
.It Ic consdev Va dev
Immediately switch the console to the specified device
.Va dev
and reprint the banner.
.Va dev
must be one of
.\" .Bl -item -width com[0123]kbd -offset indent -compact
.Ar pc , com0 , com1 , com2 ,
.Ar com3 , com0kbd , com1kbd , com2kbd ,
.Ar com3kbd ,
or
.Ar auto .
See
.Sx Console Selection Policy
in
.Xr x86/boot_console 8 .
.It Ic dev Op Va device
Set the default drive and partition for subsequent filesystem
operations.
Without an argument, print the current setting.
.Va device
is of the form specified in
.Cm boot .
.It Ic help
Print an overview about commands and arguments.
.\" .It Ic load Va module Op Va arguments
.\" [x86 only]
.It Ic ls Op Pa path
Print a directory listing of
.Pa path ,
containing inode number, filename, and file type.
.Pa path
can contain a device specification.
.\" .It Ic multiboot Va kernel Op Va arguments
.\" [x86 only]
.It Ic quit
Reboot the system.
.\" .It Ic userconf Va command
.\" [x86only]
.El
.Pp
In an emergency, the bootstrap methods described in the
.Nx
installation notes for the specific architecture
can be used.
.Sh FILES
.Bl -tag -width /usr/mdec/bootxx_fstype -compact
.It Pa /boot
boot program code loaded by the primary bootstrap
.\" .It Pa /boot.cfg
.\" optional configuration file
.\" [x86 only]
.It Pa /netbsd
system code
.It Pa /netbsd.gz
gzip-compressed system code
.It Pa /usr/mdec/boot
master copy of the boot program (copy to /boot)
.It Pa /usr/mdec/bootxx_fstype
primary bootstrap for filesystem type fstype, copied to the start of
the
.Nx
partition by
.Xr installboot 8 .
.El
.Sh SEE ALSO
Architecture-specific
.Xr boot 8
manual pages (such as
.Xr emips/boot 8 ,
.Xr sparc64/boot 8 ,
.Xr x86/boot 8 ) ,
.Xr ddb 4 ,
.Xr userconf 4 ,
.\" .Xr boot.cfg 5 [x86 only] ,
.Xr halt 8 ,
.Xr installboot 8 ,
.Xr reboot 8 ,
.Xr rescue 8 ,
.Xr shutdown 8 ,
.Xr boothowto 9
.Sh BUGS
The kernel file name must be specified before, not after, the boot options.
Any
.Ar filename
specified after the boot options, e.g.:
.Pp
.Bd -unfilled -offset indent -compact
.Cm boot -d netbsd.test
.Ed
.Pp
is ignored, and the default kernel is booted.