Home > Articles > Operating Systems, Server > Solaris

This chapter is from the book

The OpenBoot Environment

  • Identify the system's boot PROM version.

The hardware-level user interface that you see before the operating system starts is called the OpenBoot PROM (OBP). OpenBoot is based on an interactive command interpreter that gives you access to an extensive set of functions for hardware and software development, fault isolation, and debugging. The OBP firmware is stored in the socketed startup PROM. The OpenBoot PROM consists of two 8KB chips on the system board: the startup PROM itself, which contains extensive firmware that allows access to user-written startup drivers and extended diagnostics, and a nonvolatile random-access memory (NVRAM) chip.

The NVRAM chip has user-definable system parameters and writable areas for user-controlled diagnostics, macros, and device aliases. NVRAM is where the system identification information is stored, such as the host ID, Ethernet address, and time-of-day (TOD) clock. A single lithium battery backup provides backup for the NVRAM and clock. Many software packages use the host ID for licensing purposes; therefore, it is important that the NVRAM chip can be removed and placed into any replacement system board. Because NVRAM contains unique identification information for the machine, Sun sometimes refers to it as the identification programmable read-only memory (ID PROM).

OpenBoot is currently at version 5. Depending on the age of your system, you could have PROM version 1, 2, 3, 4, or 5 installed. The original boot PROM firmware, version 1, was first introduced on the Sun SPARCstation 1. The first version of the OpenBoot PROM was version 2, and it first appeared on the SPARCstation 2 system. OpenBoot versions 3 and 4 are the versions that are currently available on the Ultra series systems. Version 5 is available on the Sun Enterprise 3500, 4500, 5500, and 6500 servers. Versions 3, 4 and 5 of the OpenBoot architecture provide a significant increase in functionality over the boot PROMs in earlier Sun systems. One notable feature of the OpenBoot firmware is a programmable user interface based on the interactive programming language Forth. In Forth, sequences of user commands can be combined to form complete programs. This capability provides a powerful tool for debugging hardware and software. Another benefit of versions 3, 4, and 5 is the Flash update feature. You can update the version 3, 4, and 5 firmware without replacing the PROM chip, but you will not be tested on updating the firmware on the exam.


No OpenBoot Environment on the Intel Platform The Intel environment has no OpenBoot PROM or NVRAM. On Intel systems, before the kernel is started, the system is controlled by the ROM basic input/output system (BIOS), the firmware interface on a PC.

Entry-Level to High-End Systems

Every Sun workstation and server except the midrange, midframe, and high-end servers has only one system board and holds only one boot PROM and NVRAM chip. The following are examples of systems that are capable of using only one system board:

  • SPARCstation 4, 5, 10, and 20

  • Sun Blade 100 and 1000

  • Ultra 1, 2, 5, 10, 30, 60, 80, 220, 250, 240, 420, and 450

  • Netra X1, T1, T1400, and T1405

  • Sun Fire V120, V480, and V880

Sun's midrange, midframe, and high-end servers can be configured with multiple CPU/memory and I/O boards. The following are examples of these systems:

  • Midrange—Enterprise 3000, 3500, 4000, 4500, 5000, 5500, 6000, and 6500

  • Midframe—Sun Fire 3800, 4800, 4810, and 6800

  • High-end—Enterprise 10000, Sun Fire 12000, and Sun Fire 15000

All other systems can be configured with multiple system boards and have special boot PROM and NVRAM arrangements. The following are some things you should be aware of on multiple-CPU systems:

  • A multiple-CPU system has a clock board to oversee the backplane communications.

  • The host ID and Ethernet address are on the clock board and are automatically downloaded to the NVRAM on all CPU boards when the POST is complete.

  • PROM contents on each CPU are compared and verified via checksums.

  • The CPU that is located in the lowermost card cage slot is the master CPU board.

  • Each CPU runs its own individual POST.

  • If these systems are configured with redundant CPU/memory and I/O boards, they can run in a degraded yet stable mode, even when some components have failed.

Accessing the OpenBoot Environment

You can get to the OpenBoot environment by using any of the following methods:

  • Halting the operating system.

  • Pressing the Stop and A keys simultaneously (Stop+A). On terminals that are connected to the serial port and do not have a Stop key, you press the Break key.

  • When the system is initially powered on. If your system is not configured to start up automatically, it stops at the user interface. If automatic startup is configured, you can make the system stop at the user interface by pressing Stop+A after the display console banner is displayed but before the system begins starting the operating system.

  • When the system hardware detects an error from which it cannot recover. (This is known as a watchdog reset.)


Alternate Methods for Stopping a System An alternate sequence that can be used to stop the system is Enter+~+Ctrl+B, which is equivalent to Stop+A. There must be an interval of more than 0.5 seconds between characters, and the entire string must be entered in less than 5 seconds. You can use this method only with serial devices acting as consoles and not for systems with keyboards of their own. To enable this alternate sequence, you must first modify the /etc/default/kbd file by removing the # from the entry:


Then you save the changes and, as root, type:

kbd -i

to put the changes into effect.

On a server with a physical keyswitch, the alternative BREAK does not work when the key is set to the Secure position.

If your console is connected to the serial port via a modem, you can send a break (Stop+A or L1+A) through the tip window by typing ~# (tilde and then the pound sign).

OpenBoot Firmware Tasks

The primary tasks of the OpenBoot firmware are as follows:

  • Test and initialize the system hardware.

  • Determine the hardware configuration.

  • Start the operating system from either a mass storage device or a network.

  • Provide interactive debugging facilities for testing hardware and software.

  • Allow modification and management of system startup configuration, such as NVRAM parameters.

Specifically, the following tasks are necessary to initialize the operating system kernel:

  1. OpenBoot displays system identification information and then runs self-test diagnostics to verify the system's hardware and memory. These checks are known as a POST.

  2. OpenBoot loads the primary startup program, bootblk, from the default startup device.

  3. The bootblk program finds and executes the secondary startup program, ufsboot, and loads it into memory. The ufsboot program loads the operating system kernel.


Using Stop+A Sparingly Forcing a system into the OpenBoot PROM by using Stop+A or Break abruptly breaks execution of the operating system. You should use these methods only as a last resort to restart the system.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020