The main purpose of this program is to load the system kernel.
As described in
this program is loaded by the firmware and provides a convenient way to load
the kernel. This program acts as an enhanced boot monitor for macppc systems,
providing a common interface for the kernel to start from.
Basic operations include:
- Loading kernels from hard disk.
- Loading kernels compressed by
- 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
command). Each time a kernel load
fails, the timeout is increased by one second. The sequence of
operations is as follows:
- If the file /etc/boot.conf exists on
the filesystem in slice ‘a’ on the first disk drive (wd0),
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.
- The header line
is displayed to the active console, where
x.xx is the version number of the
>> OpenBSD/macppc BOOT
boot program, followed by the
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
attempts to load the kernel
. 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 
- Boots the kernel image specified by image
with any options given. Image specification consists of a pair
either or both can be omitted (`:' is not needed if both are omitted), in
which case values from
will be used.
The only bootable devices, at the moment, are IDE devices connected to the
internal controller; they are detected as ‘wd’ devices.
Therefore, to boot kernel /bsd from
slice ‘a’ on the first hard drive, specify “boot
- Causes the kernel to ask for the
root device to use.
- Causes the kernel to go into
- Causes the kernel to drop into
ddb(4) at the
earliest convenient point.
- Causes the kernel to boot single-user.
- echo [
- Displays args on the console device.
- Prints a list of available commands.
- ls [
- 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.
- set 
- 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:
- Address at which to load the kernel.
- Debug flag if
boot was compiled
with DEBUG defined.
- Boot device name (e.g.,
- Options to pass to the loaded kernel.
- File name containing the kernel image.
- Number of seconds boot will wait for human intervention before booting
the default kernel image.
- Displays system time and date.
- system bootstrap
- system bootstrap's startup file
- kernel image
- kernel image for installation/recovery
Boot the default kernel:
Remove the 5 second pause at boot-time permanently, causing
to load the kernel immediately without
# echo "boot" >
Boot the kernel named /bsd
from the second
hard disk in “User Kernel Configuration” mode (see
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
boot> boot wd1a:/bsd
This program was written by Michael Shalayeff for OpenBSD
on the i386 platform, and was later ported to the macppc