Upon completion of this module, you should be able to use OBP commands to do the following:
1,gather general information about the system
2,define the meaning of the non-volatile read access memory(NVRAM) variables
3,display and capture the names of the devices in the system device tree, and display their attributes
4,test devices using the device path, node name, and device alias
5,generate and test a PROM device alias
6,alter and display NVRAM settings, and reset to the defaults
7,use the eeprom command to examine and define NVRAM
The OBP consists of two chips on each system board:
the boot PROM itself
a non-volatile random access memory(NVRAM)
The OBP has the following features:
the ability to read plug-in device drivers and diagnostics from probed devices.
A FORTH code interpreter to facilitate writing and downloading drivers, diagnostics, and parameters
a device tree with a data structure hierarchy, similar to UNIX, for locating device addresses
diagnostic and informational commands, and system configuration parameters(PROM variables)
a restricted monitor
system initialization
power-on self tests(POSTs)
You can use the printenv command at the monitor prompt to see the various NVRAM parameters and default values
The superuser can display and change PROM variable settings using the eeprom command
# /usr/sbin/eeprom diag-switch?=true
The default boot sequence:
ok boot->execute primary boot-OBP->load bootblk program->load and start secondary boot(/platform/'uname -m'/ufsboot)->load and start kernel(/platform/'uname -m'/kernel/unix)->kernel reads /etc/system->kernel initialized->kernel starts the init process->read /etc/default/init and /etc/inittab->execute rc scripts
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