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IRIX Advanced Site and Server Administration Guide

Chapter 4
The Command (PROM) Monitor

This chapter describes the Command (PROM) Monitor, which controls the boot environment for all IRIS workstations or servers. With the Command Monitor, you can boot and operate the CPU under controlled conditions, run the CPU in Command Monitor mode, and load programs (for example, the operating system kernel, /unix).

PROM stands for Programmable Read-Only Memory. PROM chips are placed in your computer at the factory with software programmed into
them that allows the CPU to boot and allows you to perform system administration and software installations. The PROMs are not part of your disk or your operating system; they are the lowest level of access available for your system. You cannot erase them or bypass them.

Note that there are numerous minor differences between machines, and you should refer to your owner's guide for information specific to your machine.

This chapter contains information on the following topics:

How to Enter the Command (PROM) Monitor

To get into the Command Monitor on most machines, follow these steps:

    Reboot the system with the reboot(1M) command, or if it is already switched off, turn it on.

    You see the following prompt:

    Starting up the system....
    To perform system maintenance instead, press <Esc>

    Press the <Esc> key. You see the following menu:

    System Maintenance Menu
    1   Start System
    2   Install System Software
    3   Run Diagnostics
    4   Recover System
    5   Enter Command Monitor

    Enter the numeral 5, and press <Return>. You see the Command Monitor prompt:


    You have entered the Command Monitor.

Summary of Command Monitor Commands

Table 4-1 summarizes the Command Monitor commands and gives each command's syntax.

Table 4-1 : Command Monitor Command Summary

Command Description Syntax
auto Boots default operating system (no arguments) auto
boot Boots with arguments boot [-ffile][-n][args]

checksum RANGE
disable Disables console; console can be gfx(0), tty(0), or tty(1) disableconsole_device

dump [-(b|h|w)] [- (o|d|u|x|c|B)] RANGE

eaddr [xx:xx:xx:xx:xx:xx]
enable Enables console; console can be gfx(0), tty(0), or tty(1) enable console_device
exit leave Command Monitor exit

fill [-(b|h|w)] [-v val] RANGE

g [-(b|h|w)] ADDRESS
go Transfers program execution to <pc>or to entry point of last booted program if <pc> omitted go [ INITIAL_PC]
help or ? Prints a Command Monitor command summary help [command]
? [command]
hinv (inventory) Prints an inventory of hardware on the system hinv
init Initializes the Command Monitor init

mcopy [-(b|h|w)] FROMRANGE TO

mcmp [-(b|h|w)] FROMRANGE TO

mfind [-(b|h|w)] [-n] RANGE VALUE
passwd Sets PROM password passwd

p [-(b|h|w)] ADDRESS VALUE
printenv Displays the current environment variables printenv [env_var_list]
resetenv Resets all environment variables to default resetenv
setenv Sets environment variables setenvenv_varstring
unsetenv Unsets an environment variable unsetenvenv_var
version Displays Command Monitor version version

Getting Help in the Command Monitor

The question mark (?) command displays a short description of a specified command. If you do not specify a command, the ? command displays a summary of all Command Monitor commands. To get help, type either help or a question mark (?).

help [command] 
? [command] 

Using Command Monitor Commands

The following sections cover these subjects:

Using the Command Line Editor in the Command Monitor

You can edit on the command line by using the commands shown in
Table 4-2.

Table 4-2 : Command Monitor Command Line Editor

Command Description
<ctrl-h>, <del>, Deletes previous character or <backspace>
<ctrl-u> Deletes entire line; question mark (?) prompts for corrected line
<ctrl-c> If a command is executing, kills current command

Syntax of Command Monitor Commands

The Command Monitor command syntax is designed to resemble the syntax of commands used with the IRIX operating system. This chapter uses IRIX notation for command descriptions:

Syntax of Command Monitor File Names

When you specify file names for Command Monitor commands, use this syntax:


If you do not specify cntrlr, unit, and partition, they default to zero. The notation shows that you can specify only a cntrlr, a cntrlr and unit, or all three variables. The commas are significant as place markers. For example, the root partition (partition 0) on a single SCSI disk system is shown as:



The /usr partition (partition 3) on the same disk would be written as:


The Command Monitor defines the devices shown in Table 4-3.

Table 4-3 : Device Names for Command Monitor Commands

Device Name Description
dkip the ESDI disk controller (ips in IRIX)
dksc the SCSI disk controller (dks in IRIX)
tpsc the SCSI tape controller (tps in IRIX)
xyl the SMD disk controller (xyl in IRIX)
ipi the IPI disk controller (ipi in IRIX)
tty CPU board duart
tty(0) the local console
tty(1) the remote console
gfx the graphics console
console the ``pseudo console'' which may be one of gfx(0), tty(0), or tty(1). See "Enabling a Console in the Command Monitor"
bootp Ethernet controller using bootp and TFTP protocols
tpqic the quarter-inch QIC02 tape drive

The PROM device notation is different from IRIX device notation. Certain environment variables (such as root and swap) are passed to higher level programs, and often require IRIX notation for the /dev device name. For example, in PROM notation, an ESDI disk partition most commonly used for swap is written:


In IRIX notation, the same disk is:


Running the Command Monitor

This section describes the commands that you use to run the Command Monitor. The Command Monitor accepts the commands listed in Table 4-1, "Command Monitor Command Summary,".

Enabling a Console in the Command Monitor

The Command Monitor can support a local console and a remote console (alone or simultaneously) through a serial port. The enable command enables a device that you want to use as a console. The Command Monitor accepts commands from the enabled console and displays output to that console.

enable console_device 

console_device can be gfx(0) for the graphics console, tty(0) for a terminal on port 1, or tty(1) for a terminal on port 2. The disable command works exactly the same way, disabling the specified console device.

Reinitializing the Processor from the Command Monitor

The init command reinitializes the processor from PROM memory, and returns you to the monitor program.

Setting a PROM Password

Your system may have a facility that allows you to require a password from users who attempt to gain access to the Command Monitor.

To determine if your system supports PROM passwords, select option 5 from the System Maintenance Menu to enter the Command Monitor. You see the Command Monitor prompt:

Command Monitor. Type "exit" to return to the menu.

Enter the command:


The system prints a list of available commands for the Command Monitor. If the passwd command is among those listed, your system supports the PROM password. If it is not listed, your system hardware does not support passwording. If you would like to upgrade your system to support passwording, please contact your sales representative.

If your system supports PROM passwording, issue the passwd command:


You see the prompt:

Enter new password:

Enter the password you want for your machine and press <Return>. You see the prompt:

Confirm new password:

Enter the password again, exactly as you typed it before. If you typed the password the same as the first time, you next see the Command Monitor prompt again. If you made a mistake, the system prints an error message and you must begin again. If you see no error message, your password is now set. Whenever you access the Command Monitor, you will be required to enter this password.

It is very important that you choose and enter your password carefully, because if it is entered incorrectly or forgotten, you may have to remove a jumper on the CPU board of your system. This procedure is different for each system type, and is described in your owner's guide. Some systems, though, allow you to reset the PROM password from IRIX by logging in as root and issuing the following command:

nvram passwd_key ""

The quotation marks with no characters or space between them are essential to remove the PROM password. You must be root to perform this operation.

Copying Hard Disks From the Command Monitor

You can copy a hard disk onto another hard disk easily through the Command Monitor. You may want to do this to create a backup disk in case of failure, or perhaps you have a specific software setup that you wish to copy for a new system. In order for this procedure to work correctly, and for the new disk to be useful, the disks must be of identical size and manufacture. Also, the system that is to receive the new disk must use the same CPU and graphics board set that the existing system uses, because the kernel is custom configured for CPU and graphics type, and the kernel will be copied exactly to the new disk.

Follow these steps:

    Bring your system down and install the new disk in the space provided for an additional disk. Select a SCSI device number that is not currently in use for the new disk. For this example, we will use device 2 on SCSI controller 0 (the integral SCSI controller) for the new disk, and device 1 on SCSI controller 0 for the disk to be copied.

    Boot the system to the System Maintenance Menu.

    Select option 5 from the System Maintenance Menu. You will see the Command Monitor prompt:


    Give the command to load the sash:


    From the sash prompt, give the command:

    cp -b 128k dksc(0,1,10) dksc(0,2,10) 

You see a ``read error'' message when the copy is complete. This is the normal message that tells you that the copying software has read the entire disk. If you see a ``write error'' message, there was an error copying the disk and you will probably have to start over or install the disk by more conventional means.

The Command Monitor Environment

The Command Monitor maintains an environment, which is a list of variable names and corresponding values (the values are actually text strings). These environment variables contain information that the Command Monitor either uses itself or passes to booted programs. The system stores some environment variables - those that are important and unlikely to change frequently - in non-volatile RAM (nvram). If you turn off power to the machine or press the Reset button, the system remembers these variables. When you change the setting of these variables using the setenv command, the PROM code automatically stores the new values in non-volatile RAM.

You can also use the /etc/nvram command to set or print the values of non-volatile RAM variables on your system. For complete information on the nvram command, see the nvram(1M) reference page.

Table 4-4, "Variables Stored in Non-volatile RAM," shows a list of the environment variables that the system stores in non-volatile RAM.

Several environment variables also exist that affect IRIX's operation. These are not stored in non-volatile RAM, but they do affect the operation of the PROM and of IRIX.

See Table 4-5, "Environment Variables That Affect the IRIX Operating System,". Table 4-4 lists non-volatile RAM variables.

Table 4-4 : Variables Stored in Non-volatile RAM

Variable Description
netaddr Specifies the local network address for booting across the Ethernet. See the bootp protocol.

dbaud Specifies the diagnostics console baud rate. You can change it by setting this variable (acceptable rates include 75, 110, 134, 150, 300, 600, 1200, 2400, 4800, 9600, and 19200), or by pressing the <Break> key. IRIS uses the dbaud rate for the diagnostics console during the entire system start-up. Pressing the <Break> key changes the baud rate only temporarily; the baud rate reverts to the value specified in dbaud or rbaud when you press the reset switch or issue an init command.
rbaud Specifies the remote console baud rate. The list of acceptable baud rates is the same as for dbaud, above.
bootfile Specifies the name of the file to use for autobooting, normally a stand-alone shell (sash).
bootmode Specifies the type of boot. The options have these meanings:
c - performs a complete cold autoboot, using the file pointed to by the bootfile variable to boot the kernel; boots sash, then boots kernel; runs power-on diagnostics.
m - (default) goes straight to the Command Monitor; clears memory; runs power-on diagnostics.
d - go straight to the Command Monitor; do not clear memory; do not run power- on diagnostics (on IRIS-4D 100, 200 and 300 series systems, this has the same effect as bootmode m).
console Specifies which console to use. The options have these meanings:
G - graphics console with the Silicon Graphics, Inc., logo in the upper left corner
g - (default) graphics console without the Silicon Graphics logo
root Specifies (in IRIX notation, such as ips0d0s0) the disk that contains the root (/ ) file system.
keybd Specifies the type of keyboard used. The default is ``df''; it should not be more than two characters. This variable provides a hook to override the normal system mechanism for determining the kind of keyboard installed in the system.

Table 4-5 lists Command Monitor environment variables that directly affect the operating system. Note that these variables are not stored in non-volatile RAM and are discarded if the machine is powered down.

Table 4-5 : Environment Variables That Affect the IRIX Operating System

Variable Description
showconfig Prints extra information as IRIX boots. If set through setenv, its value must be istrue.
initstate Passed to IRIX, where it overrides the initdefault line in /etc/inittab. Permitted values are s and the numbers 0-6. See init(1M).
swap Specifies in IRIX notation the swap partition to use. If not set, it defaults to the partition configured into the operating system, which is normally partition 1 on the drive specified by the root environment variable.
path Specifies a list of device prefixes that tell the Command Monitor where to look for a file, if no device is specified.
verbose Tells the system to display detailed error messages.

When you boot a program from the Command Monitor, it passes the current settings of all the environment variables to the booted program.

Displaying the Current Environment Variables

The printenv command displays the Command Monitor's current environment variables.

printenv [env_var_list] 

To change (reset) the variables, see the next section.

Changing Environment Variables

The setenv command changes the values of existing environment variables or creates new environment variables.

setenv env_var string 

env_var is the variable you're setting, and string is the value you assign to that variable. To see the current monitor settings, use printenv.

When you use setenv to change the value of one of the stored environment variables in Table 4-4, the system automatically saves the new value in non-volatile RAM. You do not need to re-enter the change the next time the machine is turned off and then on again.

Setting the Keyboard Variable

If the keybd variable is set to anything but the default df, the appropriate keyboard translation table is loaded from the volume header of the hard disk. If the table is missing or unable to load, then the default table stored in the PROMs is used. The keybd variable can be set to any value, but the keyboard translation table should be loaded from the volume header on the hard disk. This variable overrides the normal system mechanism for determining the kind of keyboard installed in the system. You should not change this variable unless you are performing keyboard diagnostics. Table 4-6 lists keybd variables suggested for international keyboards:

Table 4-6 : keybd Variables for International Keyboards

Variable Description
be Belgian
da Danish
de German
df the default
fr French
it Italian
no Norwegian
sf Swiss-French
sd Swiss-German
es Spanish
sv Swedish
uk United Kingdom
us United States (available on all models)

Removing Environment Variables

The unsetenv command removes the definition of an environment variable.

unsetenv env_var 

env_var is the variable whose definition you are removing (see setenv, above). Note that variables stored in non-volatile RAM cannot be unset.

Booting a Program from the Command Monitor

This section describes each Command Monitor boot command and shows you how to use it. When you reboot or press the Reset button, you start up the Command Monitor. Do not press the Reset button under normal circumstances, that is, when the workstation is running IRIX.

Booting a Default File

The auto command reboots the operating system. It uses the default boot file as though you were powering up the CPU. At the Command Monitor prompt (>>), type:


The PROM's environment variable bootfile specifies the default boot file. In addition, you must set the environment variable root to the disk partition that IRIX uses as its root file system. The auto command assumes that the desired image of IRIX resides on the partition specified by root of the drive specified in the environment variable bootfile.

The bootfile name can contain no more than 14 characters. To select a different boot file, see "Changing Environment Variables".

Booting a Specific Program

The boot command starts the system when you want to use a specific boot program and give optional arguments to that program. The syntax of the boot command is:

boot[-f program][-n][args] 

-f specifies the program you want to boot. The program name must contain fewer than 20 characters. If you do not specify this option, the environment variable bootfile specifies the default program. boot normally loads sash.

When you specify a program, you can include a device specification. If you don't, the Command Monitor uses the device specifications in the environment variable path. The Command Monitor tries in turn each device that you specify in path, until it finds the program you request, or until it has tried all the devices listed in path.

For example, to boot the disk formatter/exerciser program (fx) from the cartridge tape drive, use this command:

boot -f tpsc(,7,)fx 

Without any arguments, boot loads the program specified in bootfile.

Booting the Standalone Shell

The Command Monitor has been designed to keep it independent of operating systems and as small as possible. Therefore, the Command Monitor cannot directly boot files residing in IRIX or other operating system file trees. However, the Command Monitor does provide a two-level boot mechanism that lets it load an intermediary program that does understand file systems; this program can then find and load the desired boot file. The program is called the standalone shell, and is referred to as sash. sash is a reconfigured and expanded version of the Command Monitor program, and includes the modules needed to handle operating system file structures. It also has enhanced knowledge about devices.

After the system software is installed, a copy of sash is located in the volume header of the first disk. The header contains a very simple file structure that the Command Monitor understands. You can also boot sash from tape or across the network if need be. To boot sash from your disk, shut down the system, and when you see the message:

Starting up the system...
To perform system maintenance instead, press Esc

Press the escape key. You may have to enter your system's Command Monitor password, if your system has one. Next, you see a menu similar to the following:

System Maintenance Menu
   (1) Start System
   (2) Install System Software
   (3) Run Diagnostics
   (4) Recover System
   (5) Enter Command Monitor

Select option 5, ``Enter Command Monitor'' from the System Maintenance Menu. You see the following message and prompt:

Command Monitor. Type "exit" to return to the menu.

To boot the standalone shell (sash), enter the command:

boot -f sash 

sash operates in interactive command mode. You see the sash prompt:


To use the multi-level boot feature, set the PROM environment variable bootfile to refer to a specific copy of sash. In normal configurations, setting bootfile to dkip(0,0,8)sash tells the Command Monitor to load sash from the ESDI disk controller 0, disk unit 0, partition 8 (the volume header). Use this syntax:

setenv bootfile "dkip(0,0,8)sash"  for ESDI drives 
setenv bootfile "dksc(0,1,8)sash"  for SCSI drives 
setenv bootfile "xyl(0,0,8)sash"   for SMD drives 
setenv bootfile "ipi(0,0,8)sash"   for IPI drives 

Then issue a boot command, as in this example for an ESDI drive:

boot dkip()unix initstate=s 

The following actions take place:

Do not issue the auto command from sash with the bootfile set as shown above. If you do, the system tries to boot sash over itself and will exit with an error.

To be able to use the auto command from sash, set bootfile to refer to the kernel, for example, dkip()unix. Even better, return to the PROM level to use the auto command.

Booting across the Network

At the heart of the operation of diskless workstations is the bootp protocol. bootp is a DARPA standard protocol supported on all IRIS workstations. One of the devices that the Command Monitor can use for booting is the Ethernet network. Silicon Graphics provides a TCP/IP boot protocol that lets you boot files that reside on another host in the network, if the other host supports the booting protocol. The network booting protocol is the bootp protocol. It is a datagram protocol that uses the User Datagram Protocol (UDP) of TCP/IP to transfer files across the Ethernet network.

To boot across the network, you must first determine the Internet address of the machine you want to boot. The Internet address is a number assigned by the network administrator of the network to which the system is attached. The format of the number is four decimal numbers between 0 and 255, separated by periods; for example: 

Use the setenv command to set the netaddr environment variable to this address; for example:

setenv netaddr 

Booting across the Network with bootp

Once you have set the netaddr environment variable, you can use bootp to refer to a remote file by using a file name of the form:

bootp()[hostname:] path 

To configure the gateway to permit cross-network forwarding, follow these steps:

    Log in as root or become the superuser by issuing the su command.

    Edit the file /etc/inetd.conf on the gateway machine. This file configures the bootp server, which is started by the inetd(1M) daemon.

    Change the bootp description so that inetd invokes bootp with the -f flag. Find this line:

    bootp  dgram  udp  wait  root  /usr/etc/bootp  bootp

    Add the -f flag to the final bootp on the line:

    bootp  dgram  udp  wait  root  /usr/etc/bootp  bootp  -f 

    Change the tftp configuration line in one of the following ways:

    Remove the -s flag from the argument list for tftpd:

    tftp   dgram  udp   wait  guest   /usr/etc/tftpd  tftpd -s 

    This allows tftpd access to all publicly readable directories. If you are concerned about a possible security compromise, you can instead explicitly list the directories to which tftpd needs access. In this case, you need to add /usr/etc:

    tftp dgram udp wait guest /usr/etc/tftpd tftpd -s /usr/etc

    See tftpd(1M) and tftp(1C) for more information.

    Signal inetd to re-read its configuration file.

    killall -1 inetd 

Booting from a Resource List

To tell the Command Monitor to load standalone commands from various resources (such as disks or other devices), set the path environment variable. (See "Changing Environment Variables".) Set the path variable as follows:

setenv path "device_name alternate_path" 

For example, issue the following commands in order:

setenv path "dkip(0,0,8) bootp()/altdir/altbootfile" 

This causes the Command Monitor to boot the file dkip(0,0,8)altbootfile. If that file fails, the Command Monitor boots bootp()/altdir/altbootfile. If that file also fails, the Command Monitor prints the message ``command not found''. Note that pathnames are separated with spaces. If the device specification is contained within a command or by bootfile, the Command Monitor ignores path. Only bootp or volume headers are understood by the PROM.

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