To perform effective device power management, system software monitors the different components of the device and determines when they are not in use. Since only device drivers are able to determine when a device is idle, and only device drivers are able to reduce power consumption of a device, the Power Management framework exports interfaces to enable communication between the system software and the device driver.
The Solaris Power Management framework provides the following:
A device-independent model for power-manageable devices
System software to implement a power management policy (which is controlled by a user-modifiable configuration file)
A set of DDI interfaces for the device driver to notify the framework of the parts of a device that can be power managed, and when those parts are idle or busy