NAME
boot
, boot.conf
— alpha-specific
bootstrap
DESCRIPTION
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:
- Loading kernels from hard disk.
- Loading kernels compressed by gzip(1).
- Providing an interactive command line.
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). Each time a kernel
load fails, the timeout is increased by one second. The sequence of
boot
operations is as follows:
- 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 commandsboot
accepts at the interactive prompt. Though default settings usually suffice, they can be changed here. - 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 theboot>
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
boot_file,
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.
COMMANDS
The following commands are accepted at the
boot
prompt:
boot
[image] [-cdns
]- Boots the specified kernel image with any options given. If
image is omitted, values from the
boot
variables will be used.-c
- Causes the kernel to go into boot_config(8) before performing autoconf(4) procedures.
-d
- Causes the kernel to drop into ddb(4) at the earliest convenient point.
-n
- Causes the kernel to ask for the
root
device to use. -s
- Causes the kernel to boot single-user.
echo
[args]- Displays args on the console device.
help
- Prints a list of available commands.
hexdump
addr size- Show size bytes of memory at address addr.
ls
[directory]- Prints contents of the specified directory in long format including: attributes and file type, owner, group, size, filename.
reboot
- Reboots the machine by initiating a warm boot procedure.
set
[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
- Debug flag if
boot
was compiled with DEBUG defined. image
- File name containing the kernel image.
timeout
- Number of seconds boot will wait for human intervention before booting the default kernel image.
FILES
- /usr/mdec/boot
- system bootstrap
- /etc/boot.conf
- system bootstrap's startup file
- /bsd
- kernel image
- /bsd.rd
- kernel image for installation/recovery
EXAMPLES
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
SEE ALSO
gzip(1), autoconf(4), ddb(4), boot_alpha(8), boot_config(8), fdisk(8), reboot(8)
HISTORY
This program was written by Michael Shalayeff for OpenBSD 2.1 on the i386 platform, and was later ported to the alpha platform.