Using The Ntwdt Driver - Sun Oracle Netra T5440 Administration Manual

system IO and disables all interrupts during a memory-delete of permanent
memory. As a result, system controller firmware and Solaris software can not
communicate during the DR operation. Note that this limitation affects neither
the dynamic addition of memory nor the deletion of a board not containing
permanent memory. In those cases, the watchdog timer's application mode can
run concurrently with the DR implementation.
You can execute the following command to locate the system boards that contain
kernel (permanent) memory:
# cfgadm -lav | grep -i permanent
If the Solaris Operating System hangs under the following conditions, the system
■
controller firmware cannot detect the Solaris software hang:
Watchdog timer's application mode is set.
■
Watchdog timer is not enabled.
■
No rearming is done by the user.
■
The watchdog timer provides partial boot monitoring. You can use the
■
application watchdog to monitor a domain reboot.
However, domain booting is not monitored for:
Bootup after a cold poweron.
■
Recovery of a hung or failed domain.
■
In the case of a recovery of a hung or failed domain, a boot failure is not detected
and no recovery attempts are made.
The watchdog timer's application mode provides no monitoring for application
■
startup. In application mode, if the application fails to start up, the failure is not
detected and no recovery is provided.

Using the ntwdt Driver

To enable and control the watchdog's application mode, you must program the
watchdog system using the LOMIOCDOGxxx IOCTLs, described in
the User API" on page
If the ntwdt driver, as opposed to the system controller, initiates a reset of the
Solaris OS on application watchdog expiration, the value of the following property
in the ntwdt driver's configuration file (ntwdt.conf) is used:
ntwdt-boottimeout="600";
In case of a panic, or an expiration of the application watchdog, the ntwdt driver
reprograms the watchdog time-out to the value specified in the property.
78.
Appendix A
"Understanding
Watchdog Timer Application Mode 77