Sun Microsystems Netra T2000 - Watchdog Timer Application Mode; Understanding the Watchdog Timer Application Mode

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APPENDIX
A
Watchdog Timer Application Mode
This appendix gives information on the watchdog timer application mode on the
server. It provides the following sections to help you understand how to configure
and use the watchdog timer and to program Alarm3:
■ “Understanding the Watchdog Timer Application Mode” on page 85
■ “Watchdog Timer Limitations” on page 86
■ “Using the ntwdt Driver” on page 88
■ “Understanding the User API” on page 88
■ “Using the Watchdog Timer” on page 89
■ “Programming Alarm3” on page 92
■ “Watchdog Timer Error Messages” on page 94
Note – Once the application watchdog timer is in use, it is necessary to reboot the
Solaris operating system in order to return to the default (non-programmable)
watchdog timer and default LED behavior (no Alarm3).
Understanding the Watchdog Timer
Application Mode
The watchdog mechanism detects a system hang, or an application hang or crash,
should they occur. The watchdog is a timer that is continually reset by a user
application as long as the operating system and user application are running.
When the application is rearming the application watchdog, an expiration can be
caused by:
■ Crash of the rearming application
■ Hang or crash of the rearming thread in the application
■ System hang