system boot program
The boot program loads and executes
the system kernel and other stand-alone programs.
Stand-alone programs execute before the operating
system is up and running, so they cannot depend
on operating system services.
In normal operation, kernels are the only
stand-alone programs ever used.
During installation of the operating system,
the boot program is placed on the hard disk
starting at logical block 0 of the active partition.
for a description of the partition table and active partitions.
The system BIOS invokes a boot
program each time the computer is reset or powered up.
The BIOS loads the first bootable image it finds on any of
the devices it searches.
Many BIOS user-interface programs allow you to specify the
list of devices to search and the order of search.
The list may include the removable media drives (floppy disk,
CD-ROM), and the hard drive.
(See your hardware documentation for instructions on doing this.)
A boot initiated from removable media has two stages:
The boot block in sector 0 of the filesystem loads boot.
boot loads and executes the kernel.
A boot initiated from the hard disk has three stages:
The system firmware loads the masterboot from absolute sector 0
on the hard disk.
The masterboot then loads the partition boot
program from the active partition.
The remainder of boot is loaded
from /stand, a bfs filesystem.
When first invoked,
displays a message indicating that it is starting the operating system
and then displays the system logo.
At this point you can
press any key to interrupt boot and
initiate the Boot Command Processor (BCP).
[boot] indicates that you
are in the BCP.
In this interactive mode you can make entries in the following syntax:
which is the same syntax as that used in the
You can change the values of parameters on the existing parameter/value
list, add new ones to the list, or remove system parameters.
for a complete list of valid parameters.)
The parameters you add, change, or remove interactively
apply only to the kernel that you are
in the process of booting, except in the following circumstance:
If you are installing for the first time (Initial System
Load), parameters added using the BCP will be automatically added
Following all other uses of the BCP you must also edit
the /stand/boot file and add, change, or
remove them there for the effect to be permanent.
The Boot Command Processor commands
can be abbreviated to a unique substring, and
is used as an argument to show, however, it
The following commands are available:
If the TIMEOUT parameter is non-zero (default is 0) and
you have not typed anything,
boot times out and resumes loading the default program.
? or help
Displays this list of commands.
Loads and runs specified program; default is BOOTPROG.
can be prefixed
to override the default device.
Standard values for device take the following forms:
specifies the floppy disk, drive number unit
specifies the hard disk, drive number unit (starting at zero),
partition number partition, and slice number slice.
partition can also be specified as an operating system
type name (
If partition is not defined, it defaults to
slice specifies the slice number for the root filesystem, allowing
the possibility of backup roots.
If device is specified without filename,
boot performs a ``raw boot'' of the specified device.
For example,to boot
DOS or Windows from the first
hard drive, use:
Lists all files in /stand directory; default device is
Displays the logo image until a key is pressed.
Turns off display of the logo image for the duration of this boot session.
show [-a | param]
Shows boot parameter values:
Shows all boot parameters, even messages.
Shows only boot parameters and messages starting with param.
Sets the value of a boot parameter.
Appends the value to a boot parameter, inserting a comma.
For example, you can use the BOOTPROG parameter to change
the name of the kernel file to boot from the /stand directory.
As delivered, the default is unix.
If you change the value of BOOTPROG to unix.old or unix.good, for example,
the boot program will load that alternate kernel from the boot filesystem.
If you specify a file that does not exist
or cannot be loaded for some reason, you will be warned and will re-enter
programs have different error messages.
The masterboot program displays an error message and
locks the system.
is a list of the most common
messages and their meanings:
Error loading operating system
Disk I/O error occurred when trying to read in the partition boot
of the active operating system.
Missing operating system
The sector loaded from the active partition is not marked as a valid
partition boot block.
(The last two bytes of the 512-byte sector must be ``0x55, 0xAA''.)
Cannot determine disk geometry
The masterboot was unable to determine the logical
geometry (cylinders, heads, etc.) of the disk.
No active partition
No partition in the partition table is marked active.
program cannot be used to load programs that have
not been linked for standalone execution.
To create stand-alone programs, use the
option of the system linker
and special stand-alone libraries.
Although stand-alone programs can operate in real or protected mode,
they must not be large or huge model programs.
Programs in real mode can use the input/output
routines of the computer's startup ROM.
© 2005 The SCO Group, Inc. All rights reserved.
SCO OpenServer Release 6.0.0 - 02 June 2005