Post And Openboot - Sun Microsystems Enterprise 3500 System Reference Manual

or use the log option:
% /usr/platform/sun4u/sbin/prtdiag -l
9.5.3

POST and OpenBoot

POST and OpenBoot work together in the system to test and manage system
hardware.
POST resides in the OpenBoot PROM on each CPU/Memory+ board and I/O+
board. When the system is turned on, or if a system reset is issued, POST detects and
tests buses, power supplies, boards, CPUs, DIMMs, and many board functions.
POST controls the status LEDs on the system front panel and all boards. POST
displays diagnostic and error messages on a console terminal, if available.
Only POST can configure the system hardware, and only POST can enable
hot-pluggable boards. If a new PCM is added to the card cage after the system has
booted, the new PCM will not work until the system is rebooted, at which time
POST reconfigures the system, using the PCMs that are found in the system at that
time.
OpenBoot provides basic environmental monitoring, including detection of
overheating conditions and out-of-tolerance voltages. For example, if an overheated
board is found, OpenBoot issues a warning message. If the temperature passes the
danger level, POST puts the overheated board(s) in low-power mode.
OpenBoot also provides a set of commands and diagnostics at the ok prompt. For
example, you can use OpenBoot to set NVRAM variables that reserve a board or a
set of DIMMs for hot-sparing.
The following OpenBoot commands may be useful for diagnosing problems:
9.5.3.1 show-devs Command
Use the show-devs command to list the devices that are included in the system
configuration.
9.5.3.2 printenv Command
Use the printenv command to display the system configuration variables stored in
the system NVRAM. The display includes the current values for these variables, as
well as the default values.
9-10 Sun Enterprise 3500 System Reference Manual • August 2001