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OpenBoot PROM (OBP) Reference


1. About this Document

This document provides a list of useful OBP commands that can be helpful when booting, configuring and performing diagnostics upon Sun SPARC hardware and clones.

Note that not all commands are available on all PROM versions. In particular, sun4c systems have a different input mode, and some JavaStation models are missing a lot of OBP functionality.

OBP is somewhat inconsistent when it comes to command names. Sometimes hyphens are used to seperate words, sometimes they are not. Some commands which display information start with or contain a dot (this is a FORTH convention).

The terms "OBP", "OpenBoot PROM" and "PROM" are used interchangably in this document.

2. Entering OBP

Systems with Sun Keyboards 

On regular Sun systems (and clones which use Sun keyboards), press Stop+A when the system boots to enter OBP. The Stop key is the top left key on the extra block of keys on the left hand side of the keyboards (on really old systems it might be marked L1).

The Stop+N keyboard combination at boot will reset many systems to the default PROM settings. Stop+D will enable diagnostics on some boards.

Over Serial Console 

To enter OBP over serial console, send a break. In minicom, do this by pressing ctrl+A F. In xc, use ctrl+A B.

Systems with Non-Sun (PC Style) Keyboards 

On systems with PC-style keyboards (such as JavaStations and some Ultra clones), ctrl+break or alt+ctrl+break is generally used.

Note that on the JavaStation JK, ctrl+break will restart the box rather than enter PROM. To get at OBP, you will need to set jumper J1300 pins 7-8 on the mainboard.

3. Basic System Commands

Halting and Restarting 

The power-off command will halt the box and turn off power. This command is sometimes screwy on Ultra5/10 systems.

The reset command will perform a soft reset. If diagnostics are enabled, they will not be rerun. In some documents, this command is refered to as reset-all.

The boot command boots the system. A parameter may be provided to override the default boot device -- this can be a full device name or a device alias such as disk, cdrom or net. Any additional arguments are passed to the bootloader or operating system.

PROM and System Information 

The .version command will show the OBP version.

Code Listing 3.1: .version output

{0} ok .version
Release 3.7 Version 0 created 1997/01/09 13:06
OBP 3.7.0 1997/01/09 13:06
POST 3.2.1 1996/12/20 03:01

The banner command will show the system information banner.

Code Listing 3.2: banner output

{0} ok banner
Sun Ultra 2 UPA/SBus (2 X UltraSPARC-II 296MHz), No Keyboard
OpenBoot 3.7, 704 MB memory installed, Serial #9705521.
Ethernet address 8:0:20:94:18:31, Host ID: 80941831

The .speed command will show bus speeds.

Code Listing 3.3: .speed output

{0} ok .speed
CPU  Speed : 296.00 MHz
UPA  Speed : 098.66 MHz
SBus Speed : 025.00 MHz

Device Information 

The show-devs command will give a list of devices available to the system.

The probe-scsi command will show internal SCSI devices available to the system. The probe-scsi-all command will show both internal and external devices on every SCSI interface. After running either of these commands, you must issue a reset-all before trying to boot an operating system.

Code Listing 3.4: probe-scsi-all output

{0} ok probe-scsi-all
This command may hang the system if a Stop-A or halt command
has been executed.  Please type reset-all to reset the system
before executing this command.
Do you wish to continue? (y/n) y
/[email protected],0/SUNW,[email protected],8800000
Target 1
  Unit 0   Disk     SEAGATE ST34371W SUN4.2G74629710B00491
                    Copyright (c) 1997 Seagate
                    All rights reserved

The probe-ide command is also available on IDE-based systems.

Code Listing 3.5: probe-ide output

ok probe-ide
  Device 0  ( Primary Master )
          ATA Model: ST320420A

  Device 1  ( Primary Slave )
          ATA Model: Maxtor 6E040L0

  Device 2  ( Secondary Master )
         Not Present

  Device 3  ( Secondary Slave )
         Not Present

4. Environment Variables and Device Aliases

Getting and Setting Environment Variables 

Use printenv to get a list of environment variables. To see the value of a specific variable, use printenv fnord.

To set a variable, use setenv myvar the new value.

To restore a variable's default value, use set-default blah. To revert all variables to default, use set-defaults.

Note that boolean variables usually end in a ?, and that they are seperate from variables of the same name without the question mark. The values true and false are used for booleans.

Useful Environment Variables 

Some useful environment variables:

Variable Meaning
ttya-mode Sets the baud rate and related settings used by the serial console. By default 9600,8,n,1,- is used, meaning 9600 baud, 8 bits, no parity, one stop bit, no flow control.
auto-boot? By default OBP will automatically boot upon startup. Set this to false if you'd rather send the boot command manually.
boot-device When auto-booting, and when boot is issued with no arguments, this variable is used to determine the boot device. More than one value can be provided (space seperated), in which case each is tried in turn. Each value can be a full device path or a device alias.
diag-device As boot-device, but used when diag-switch? is enabled.
local-mac-address? If set, network interfaces will use their own MAC rather than the system-wide MAC. This is consistent with how PCs behave, and in violation of the Ethernet specification.
diag-switch? If set, additional diagnostic checks will be run at power on. Note that this can take a very long time on SMP and / or HyperSparc systems. In addition, the diag-device variable will also be used to determine the boot device rather than boot-device. Some systems have a mainboard jumper or a switch on the front of the machine which forces this setting on.

Getting and Setting Device Aliases 

Device aliases can be used to simplify the arguments to many commands. Instead of typing boot /sbus/SUNW,[email protected],8c00000, for example, one could use boot net. A number of device aliases are defined by default on every system.

To view all device aliases, use the devalias command. To view a specific alias, use devalias whatever. To set a device alias, use devalias whatever newvalue.

Changing Monitor Resolutions 

The output-device variable can be used to control which framebuffer is used, and at what resolution it is run, for PROM console. For example, to use the Creator card on an Ultra 1C or 2 at a resolution of [email protected]:

Code Listing 4.1: Changing Monitor Settings

{0} ok devalias screen /SUNW,ffb
{0} ok setenv output-device screen:r1024x768x76

Changes will not take effect until after a reset. Not all resolutions and refresh are available on all cards.

5. Diagnostics

Entering Diagnostic Mode 

Before running any diagnostics, it is best to enable diag-switch? and do a full power off / on cycle (hard power off). Additional diagnostic information will be provided over the serial console when the machine boots.

Basic Tests 

If the power on self test (POST) succeeds, additional tests can be performed using the test, test-all, watch-net and watch-clock commands.

The test somedevice command will perform checks upon the specified device (this can be a full device path or a device alias).

Code Listing 5.1: Example Tests

{0} ok test scsi
        CE DMA fill from address fff8e000 for 80 bytes   succeeded.
         Dma register test -- succeeded.
         Esp register test -- succeeded.
         Dma read test -- succeeded.
         Dma write test -- succeeded.
{0} ok test /sbus/SUNW,hme
Internal loopback test -- succeeded.
Transceiver check  -- Using Onboard Transceiver - Link Up.
{0} ok test ttya
 !"#$%&'()*+,-./0123456789:;<=>[email protected][\]^_`abcdefghijklmn

The test-all command will perform checks upon every device capable of self tests.

The watch-net command can be used to watch for broadcast packets being sent over the network.

The watch-clock command can be used to verify that the internal clock is working. It should count from 0 to 59 in a loop with an interval of one second.

Extended Diagnostics Using obdiag 

Note: The obdiag routines are only available on the Ultra 5/10 and later.

To enable extended diagnostics mode, run the following:

Code Listing 5.2: Entering obdiag

ok setenv mfg-mode on
mfg-mode =            on
ok setenv diag-switch? true
diag-switch? =        true
ok setenv auto-boot? false
auto-boot? =          false
ok reset-all
ok obdiag

This should display a menu. First, select 16 to enable verbose messages.

Code Listing 5.3: obdiag menu

          OBDiag Menu

  0 ..... PCI/Cheerio
  1 ..... EBUS DMA/TCR Registers
  2 ..... Ethernet
  3 ..... Keyboard
  4 ..... Mouse
  5 ..... Floppy
  6 ..... Parallel Port
  7 ..... Serial Port A
  8 ..... Serial Port B
  9 ..... NVRAM
 10 ..... Audio
 11 ..... EIDE
 12 ..... Video
 13 ..... All Above
 14 ..... Quit
 15 ..... Display this Menu
 16 ..... Toggle script-debug
 17 ..... Enable External Loopback Tests
 18 ..... Disable External Loopback Tests

 Enter (0-13 tests, 14 -Quit, 15 -Menu) ===> 16
 Enter (0-13 tests, 14 -Quit, 15 -Menu) ===>

Individual tests can then be run by selecting the relevant number. Note that some tests (for example, serial ports) assume that an external loopback connector is attached. The Ethernet test assumes that a cable is attached and connected to a switch.

To exit, use 14.

6. References

The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license.
Updated August 27th, 2004
Ciaran McCreesh

Summary:  The OpenBoot PROM (OBP) Reference provides a list of useful OBP commands that can help when booting, configuring and performing diagnostics upon Sun SPARC hardware and clones.
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Copyright 2001-2004 Gentoo Foundation, Inc. Questions, Comments, Corrections? Email [email protected].