boot_macppc - macppc system bootstrapping procedures
System startup
When powered on, after a panic, or if the system is rebooted
via
reboot(8) or shutdown(8), the Open Firmware will proceed to
its initialization,
and will boot an operating system if the auto-boot?
variable is
set to ``true'', or will wait for interactive commands otherwise.
Boot process description [Toc] [Back]
The Apple Open Firmware will normally load the kernel from
the device and
filename as instructed by the boot-device and boot-file
variables. If
the boot-file variable is empty, the OpenBSD bootloader will
look for a
kernel named bsd, unless a different filename has been specified in the
boot command. To reset this variable to its default, empty,
value, type
the following:
ok set-default boot-device
The OpenBSD bootstrap program is named ``ofwboot''. It can
be installed
either in a HFS partition or in a MSDOS partition on the
disk. If MBR
partitioning is chosen for the disk, the bootstrap program
will be installed
automatically during the OpenBSD installation procedure. For HFS
shared disks, the ofwboot file must be installed manually.
The ofwboot
program can be loaded from any Open Firmware recognized disk
or network
device.
Boot process options [Toc] [Back]
If invoked manually without parameters, or if the specified
kernel could
not be loaded, the OpenBSD bootloader will let the user enter a boot device,
kernel filename and boot options.
If the special line exit is entered, the bootloader will attempt to
restart the machine.
The file specification used is of the form:
promdev:partition/filename options
where: ``promdev'' is an optional Open Firmware device name
(such as
``hd'' or ``ide'') and ``partition'' is an optional disk
partition number.
Normal line editing characters can be used when typing
the file
specification.
The following options are recognized:
-a Prompt for the root filesystem and swap devices
after the devices
have been configured.
-c Enter the ``User Kernel Config'' mode upon
startup (see
boot_config(8)).
-d Enter the debugger, ddb(4), as soon as the kernel console has
been initialized.
-s Boot the system single-user. The system will be
booted multi-user
unless this option is specified.
Abnormal system termination [Toc] [Back]
In case of system crashes, the kernel will usually enter the
kernel debugger,
ddb(4), unless it is not present in the kernel, or
it is disabled
via the ddb.panic sysctl. Upon leaving ddb, or if ddb was
not entered,
the kernel will halt the system if it was still in device
configuration
phase, or attempt a dump to the configured dump device, if
possible. The
crash dump will then be recovered by savecore(8) during the
next multiuser
boot cycle. It is also possible to force other behaviours from ddb.
Accessing the PROM [Toc] [Back]
The prom can only be accessed during system reset, or at
power-up. To
enter Open Firmware, press and hold ``Cntrl'' ``Cmd'' ``o''
``f'' as the
machine resets until it enters the Open Firmware debugger.
On an Xserve using serial console the System Identifier button is used to
enter Open Firmware instead of the keyboard. To enter Open
Firmware,
hold down the System Identifier button while pressing the
Power button.
When the upper LED bank begins lighting up in sequence, repeatedly press
the System Identifier button until the seventh LED from the
right is
highlighted in the lower bank. Now hold the System Identifier button for
two seconds, until all the top row LEDs light up.
/bsd default system kernel
/usr/mdec/ofwboot system bootstrap (usually installed on a
stand-alone
FAT partition or an Apple HFS partition,
to be readable
by Open Firmware)
ddb(4), boot_config(8), halt(8), init(8), installboot(8),
reboot(8),
savecore(8), shutdown(8)
OpenBSD 3.6 September 22, 2002
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