OpenBSD manual page server

Manual Page Search Parameters
BOOT(8) System Manager's Manual (alpha) BOOT(8)

boot, boot.conf — alpha-specific bootstrap

The main purpose of this program is to load the system kernel.

As described in boot_alpha(8), this program is loaded by the SRM firmware and provides a convenient way to load the kernel. This program acts as an enhanced boot monitor for alpha systems, providing a common interface for the kernel to start from.

Basic operations include:

The sequence of its operation is as follows: initialization, parsing the configuration file, then an interactive command line. While at the command line you have 5 seconds to type any commands, if needed. If time expires, the kernel will be loaded according to the current variable settings (see the set command). If the kernel load fails, a second attempt is made with the timeout increased by one second. The sequence of boot operations is as follows:

  1. If the file /etc/boot.conf exists on the filesystem in slice ‘a’ on the disk boot was loaded from, open and parse it. Lines beginning with the ‘#’ character, as well as whitespace at the beginning of lines, are ignored. The file may contain any commands boot accepts at the interactive prompt. Though default settings usually suffice, they can be changed here.
  2. The header line

    >> OpenBSD/alpha BOOT [x.xx]

    is displayed to the active console, where x.xx is the version number of the boot program, followed by the

    boot>

    prompt, which means you are in interactive mode and may enter commands. If you do not, boot will proceed to load the kernel with the current parameters after the timeout period has expired.

By default, boot attempts to load the kernel executable specified in the SRM environment variable , defaulting to /bsd if not set. If it fails to find the kernel and no alternative kernel image has been specified, the system will be unable to boot.

The following commands are accepted at the boot prompt:

[image] [-cdns]
Boots the specified kernel image with any options given. If image is omitted, values from the boot variables will be used.
Causes the kernel to go into boot_config(8) before performing autoconf(4) procedures.
Causes the kernel to drop into ddb(4) at the earliest convenient point.
Causes the kernel to ask for the root device to use.
Causes the kernel to boot single-user.
[args]
Displays args on the console device.
Prints a list of available commands.
addr size
Show size bytes of memory at address addr.
[directory]
Prints contents of the specified directory in long format including: attributes and file type, owner, group, size, filename.
Reboots the machine by initiating a warm boot procedure.
[varname [value]]
If invoked without arguments, prints a list of variables and their values. If only varname is specified, displays contents of that variable. If varname and value are both specified, sets that variable to the given value. Variables include:

Debug flag if boot was compiled with DEBUG defined.
File name containing the kernel image.
Number of seconds boot will wait for human intervention before booting the default kernel image.

/usr/mdec/boot
system bootstrap
/etc/boot.conf
system bootstrap's startup file
/bsd
kernel image
/bsd.rd
kernel image for installation/recovery

Boot the default kernel:

boot> boot

Remove the 5 second pause at boot-time permanently, causing boot to load the kernel immediately without prompting:

# echo "boot" > /etc/boot.conf

Boot the kernel named /obsd in “User Kernel Configuration” mode (see boot_config(8)). This mechanism allows for the explicit enabling and disabling of devices during the current boot sequence, as well as the modification of device parameters. Once booted, such changes can be made permanent by using config(8)'s -e option.

boot> boot /obsd -c

gzip(1), autoconf(4), ddb(4), boot_alpha(8), boot_config(8), fdisk(8), reboot(8)

This program was written by Michael Shalayeff for OpenBSD 2.1 on the i386 platform, and was later ported to the alpha platform.

November 5, 2024 OpenBSD-current