The OpenBoot Environment
Execute basic boot PROM commands for a SPARC system.
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 system's PROM chip.
Sun UltraSPARC systems use a programmable boot PROM that allows new boot program data to be loaded into the PROM by "flashing" the PROM with software. This type of PROM is called a flash PROM (FPROM).
The NVRAM chip stores user-definable system parameters, also referred to as NVRAM variables or EEPROM parameters. The parameters allow administrators to control variables such as the default boot device and boot command. The NVRAM also contains writeable 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. On older systems, a single lithium battery backup provides backup for the NVRAM and clock. Newer systems contain a non-removable Serial Electronically Erasable Programmable Read-Only Memory (SEEPROM) chip that does not require a battery. Other newer systems may contain a removable system configuration card to hold the system configuration information. 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 but is available only on high-end Sun servers (SunFire and higher). Depending on the age of your system, you could have PROM version 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 and Enterprise 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.
To determine the version of the OpenBoot PROM, type
prtconf -v .
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 basic input/output system (BIOS), the firmware interface on a PC. Therefore, many features provided by OpenBoot are not available on Intel systems.
Entry-Level to High-End Systems
Sun's midrange, midframe, and high-end servers, such as the Enterprise and Sun Fire, can be configured with multiple CPU/memory and I/O boards.
The following are some things you should be aware of on multiple-CPU systems:
Accessing the OpenBoot Environment
System Control Switch
On those servers with a power button and system control switch located on the system's front panel, the ability to turn the system on or off is controlled by the key position on the system control switch.
The four-position system control switch (key) located on the system's front panel controls the power-on modes of the system and prevents unauthorized users from powering off the system or reprogramming system firmware. Table 3.1 describes the function of each system control switch setting:
Alternative Methods for Stopping a System An alternative 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 alternative sequence, you must first modify the /etc/default/kbd file by removing the # from the entry:
Remember to uncomment the line by removing the "#".
Then you save the changes and, as root, type
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).
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. When you access the ok prompt from a running system, you are suspending the operating environment software and placing the system under firmware control. Any processes that were running under the operating environment software are also suspended, and the state of such software may not be recoverable.
The diagnostics and commands that you run from the ok prompt have the potential to affect the state of the system. Don't assume that you will be able to resume execution of the operating environment software from the point at which it was suspended. Although the go command will resume execution in most circumstances, as a rule, each time you drop the system down to the ok prompt, you should expect to have to reboot it to get back to the normal operating state.
OpenBoot Firmware Tasks
Specifically, the following tasks are necessary to initialize the operating system kernel: