System power management involves saving the state of the system prior to powering the system down. Thus, the system can be returned to the same state immediately when the system is turned back on.
To shut down an entire system with return to the state prior to the shutdown, take the following steps:
Stop kernel threads and user processes. Restart these threads and processes later.
Save the hardware state of all devices on the system to disk. Restore the state later.
The System Power Management framework in the Oracle Solaris OS provides the following features for system power management:
A platform-independent model of system idleness.
A set of interfaces for the device driver to override the method for determining which drivers have hardware state.
A set of interfaces to enable the framework to call into the driver to save and restore the device state.
A mechanism for notifying processes that a resume operation has occurred.