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Ask Al – How can I reset the NVRAM parameters to their default settings?

October 6th, 2011

I have a Sun Blade with a USB keyboard and mouse. The administrator modified some of the NVRAM variables in Solaris using the eeprom command. After a reboot we no longer see video and the keyboard no longer works. I believe it has to do with the NVRAM variables. In the past I was able to reset the NVRAM variables by holding down the {stop}-{n} keys and powering on the system. However, this does not work now. How can I reset the NVRAM parameters to their default settings?

Newer Sun systems tend to have USB keyboards and mice. These USB devices are not initialized until the end of the POST process. If the keyboard is not initialized, the {stop}-{n} keys are ineffective. Use the following procedure to reset the NVRAM variables to their default settings for all systems that use a USB keyboard, RSC, LOM, or ALOM.

Stop-N Sequence
The Stop-N sequence (Bypass) is used to bypass problems that may be encountered on a system with wrongly configured NVRAM variables. This NVRAM reset procedure may be used on any systems that do not have a Mini-Din style keyboard attached.

The system must be at a powered off state before it can be implemented. The step by step procedure below goes through the process of implementing Stop-N sequence.


1. Power on the system.
2. While POST is running, both the System Status Fault and OK-to-Remove LEDs (if applicable) will simultaneously blink together.
3. When ONLY the System Status Fault LED begins to RAPIDLY blink, press the Power Button twice, with a one second delay between each press.

Note: Depending of the system, the system configuration and POST level, it could take up to 30 minutes until the System Fault LED rapidly blinks.

4. Once engaged into this mode, a printout notifies that NVRAM values have been set to their default values (see example below).

Setting NVRAM parameters to default values. Probing I/O buses
Sun Fire V890, No Keyboard
Copyright 1998-2004 Sun Microsystems, Inc. All rights reserved.
OpenBoot x.x, xxxx MB memory installed, Serial #xxxxxxxx.
Ethernet address x:x:x:x:x:x, Host ID: xxxxxxxx.
System is operating in Safe Mode and initialized with factory
default configuration. No actual NVRAM configuration variables
have been changed; values may be displayed with ‘printenv’ and set
with ‘setenv’. System will resume normal initialization and
configuration after the next hardware or software reset.

5. When the system reaches the OpenBoot PROM “ok” prompt, every NVRAM variable is set back to its misconstrued state.
6. To display all NVRAM variable values, use the printenv Command at the “ok” prompt.
7. NVRAM variables can be changed by implementing the setenv Command at the “ok” prompt per specific variables. To permanently set all variables back to their default values, implement the set-defaults Command at the “ok” prompt.

Alternative Method 1

Because it could take up to 30 minutes for the System Status Fault LED to rapidly blink, an alternative method for resetting the NVRAM variables to their default values is described below:

Note: This method will not decrease the time required to reset the variables. It eradicates the need to watch the LEDs and press the power button.

• If the Keyswitch is in the “Diagnostics” position, all NVRAM variables are temporally set to their defaults values (except diag-level which is set to max). After running the extended POST the system goes to the OpenBoot PROM “ok” prompt. Variables may be displayed using the printenv Command and defined using the setenv Command. To permanently reset all variables to the default settings, issue the set-defaults Command.

Note: This method only works if the system firmware is 4.15.x or newer.

Alternative Method 2

• Remote System Control: At the Remote System Control “rsc>” prompt, issue the bootmode nvram_reset Command. This has a similar function as the Stop-N keystroke sequence.

Do you have a question you’d like to have answered? Email Allen at askal@stsolutions.com

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