NAME
boot
-
system bootstrapping procedures
DESCRIPTION
This document provides information on using common features in the
NetBSD
boot loader.
Additional information may be found in
architecture-specific
boot(8)
manual pages.
In the native
NetBSD
boot protocol, options are passed from the boot loader
to the kernel via flag bits in the
boothowto
variable, which is interpreted by the kernel in much the same way
as the
howto
argument passed to the
reboot(2)
system call.
Interactive mode
In interactive mode, the boot loader will present a prompt, allowing
input of these commands:
- Xo boot
-
[device]:
[filename]
[-1234abcdmqsvxz]
The default
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.
device
is of the form
[N[x]]
where
xd
is the device from which to boot,
N
is the unit number, and
x
is the partition letter.
The following list of supported devices may vary from installation to
installation:
- hd
-
Hard disks.
- fd
-
Floppy drives.
The default
filename
is
netbsd
;
if the boot loader fails to successfully
open that image, it then tries
netbsd.gz
(expected to be a kernel image compressed by gzip), followed by
netbsd.old
,
netbsd.old.gz
,
onetbsd
,
and finally
onetbsd.gz
.
Alternate system images can be loaded by just specifying the name of the image.
Options are:
- -1
-
Sets the machine-dependent flag
RB_MD1
in
boothowto.
- -2
-
Sets the machine-dependent flag
RB_MD2
in
boothowto.
- -3
-
Sets the machine-dependent flag
RB_MD3
in
boothowto.
- -4
-
Sets the machine-dependent flag
RB_MD4
in
boothowto.
- -a
-
Sets the
RB_ASKNAME
flag in
boothowto.
This causes the kernel to prompt for the root file system device,
the system crash dump device, and the path to
init(8).
- -b
-
Sets the
RB_HALT
flag in
boothowto.
This causes subsequent reboot attempts to halt instead of rebooting.
- -c
-
Sets the
RB_USERCONF
flag in
boothowto.
This causes the kernel to enter the
userconf(4)
device configuration manager as soon as possible during the boot.
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.
- -d
-
Sets the
RB_KDB
flag in
boothowto.
Requests the kernel to enter debug mode, in which it
waits for a connection from a kernel debugger; see
ddb(4).
- -m
-
Sets the
RB_MINIROOT
flag in
boothowto.
Informs the kernel that a mini-root file system is present in memory.
- -q
-
Sets the
AB_QUIET
flag in
boothowto.
Boot the system in quiet mode.
- -s
-
Sets the
RB_SINGLE
flag in
boothowto.
Boot the system in single-user mode.
- -v
-
Sets the
AB_VERBOSE
flag in
boothowto.
Boot the system in verbose mode.
- -x
-
Sets the
AB_DEBUG
flag in
boothowto.
Boot the system with debug messages enabled.
- -z
-
Sets the
AB_SILENT
flag in
boothowto.
Boot the system in silent mode.
- consdev dev
-
Immediately switch the console to the specified device
dev
and reprint the banner.
dev
must be one of
pc, com0, com1, com2,
com3, com0kbd, com1kbd, com2kbd,
com3kbd,
or
auto.
See
Console Selection Policy
in
boot_console(8).
- dev[ device]
-
Set the default drive and partition for subsequent filesystem
operations.
Without an argument, print the current setting.
device
is of the form specified in
boot.
- help
-
Print an overview about commands and arguments.
- ls[
path
] -
Print a directory listing of
path
,
containing inode number, filename, and file type.
path
can contain a device specification.
- quit
-
Reboot the system.
In an emergency, the bootstrap methods described in the
NetBSD
installation notes for the specific architecture
can be used.
FILES
/boot
-
boot program code loaded by the primary bootstrap
/netbsd
-
system code
/netbsd.gz
-
gzip-compressed system code
/usr/mdec/boot
-
master copy of the boot program (copy to /boot)
/usr/mdec/bootxx_fstype
-
primary bootstrap for filesystem type fstype, copied to the start of
the
NetBSD
partition by
installboot(8).
SEE ALSO
Architecture-specific
boot(8)
manual pages,
ddb(4),
userconf(4),
halt(8),
installboot(8),
reboot(8),
rescue(8),
shutdown(8)
BUGS
The kernel file name must be specified before, not after, the boot options.
Any
filename
specified after the boot options, e.g.:
-
boot -d netbsd.test
is ignored, and the default kernel is booted.