Device Power Management entries are now obsolete and support for them will be removed in a future release. If a device supports original Power Management interfaces, it needs to be explicitly configured for Power Management using an entry of the form shown below. A device will not be power managed if there is no entry for the device. Be sure you fully understand the Power Management framework before you attempt to modify device Power Management entries.

Device Power Management entries consist of line-by-line listings of the devices to be configured. Each line is of the form:

device_name threshold...dependent_upon...

The fields must be in the order shown above. Each line must contain a device_name field and a threshold field; it may also contain a dependent_upon field. Fields and sub-fields are separated by white space (tabs or spaces). A line may be more than 80 characters. If a newline character is preceded by a backslash (\) it will be treated as white space. Comment lines must begin with a hash character (#).

The device_name field specifies the device to be configured. device_name is either a pathname specifying the device special file or a relative pathname containing the name of the device special file. (For the latter format, you can avoid using the full pathname by omitting the pathname component that specifies the parent devices. This includes the leading '/'.) Using the relative pathname format, the first device found with a full pathname containing device_name as its tail is matched. In either case, the leading /devices component of the pathname does not need to be specified.

The threshold field is used to configure the power manageable components of a device. These components represent entities within a device that may be power-managed separately. This field may contain as many integer values as the device has components. Each threshold time specifies the idle time in seconds before the respective component may be powered down. If there are fewer component threshold times than device components, the remaining components are not power managed. Use a value of -1 to explicitly disable power-down for a component. At least one component threshold must be specified per device (in the file).

The dependent_upon field contains a list of devices that must be idle and powered-down before the dependent device in device_name field can be powered down. A device must previously have been configured before it can be used in dependent_upon list. This field should only list logical dependents for this device. A logical dependent is a device that is not physically connected to the power managed device (for example, the display and the keyboard). Physical dependents are automatically considered and do not need to be included.

A device Power Management entry is only effective if there is no user process controlling the device directly. For example, X Window systems directly control framebuffers and entries in this file are effective only when X Windows are not running.

Devices whose drivers use the new automatic device Power Management interfaces (as evident by existence of pm-components(9P) property) are automatically power managed if enabled by the autopm entry described below.

When a component has been idle at a given power level for its threshold time, the power level of the component will be reduced to the next lower power level of that component (if any). For devices which implement multiple components, each component is power-managed independently.

Default thresholds for components of automatically power managed devices are computed by the Power Management framework based on the system idleness threshold. By default, all components of the device are powered off if they have all been idle for the system's idleness threshold. The default system idleness threshold is determined by the applicable United States Environmental Protection Agency's (EPA) Energy Star Memorandum of Understanding. See the NOTES section of this manual page for more information.

To set the system idleness threshold, use one of the following entries:

system-threshold     threshold 

system-threshold    always-on

where threshold is the value of the system idleness threshold in hours, minutes or seconds as indicated by a trailing h, m or s (defaulting to seconds if only a number is given). If always-on is specified, then by default, all devices will be left at full power.

To override the default device component thresholds assigned by the Power Management framework, a device-thresholds entry may be used. A device-thresholds entry sets thresholds for a specific automatically power-managed device or disables automatic Power Management for the specific device.

A device-thresholds entry has the form:

device-thresholds          phys_path     (threshold ...) ...

or

device-thresholds         phys_path       threshold

or

device-thresholds        phys_path        always-on

where phys_path specifies the physical path (libdevinfo(3)) of a specific device. For example, /pci@8,600000/scsi@4/ssd@w210000203700c3ee,0 specifies the physical path of a disk. A symbolic link into the /devices tree (for example /dev/dsk/c1t1d0s0) is also accepted. The thresholds apply (or keeping the device always on applies) to the specific device only.

In the first form above, each threshold value represents the number of hours, minutes or seconds (depending on a trailing h, m or s with a default to seconds) to spend idle at the corresponding power level before power will be reduced to the next lower level of that component. Parentheses are used to group thresholds per component, with the first (leftmost) group being applied to component 0, the next to component 1, etc. Within a group, the last (rightmost) number represents the time to be idle in the highest power level of the component before going to the next-to-highest level, while the first (leftmost) number represents the time to be idle in the next-to-lowest power level before going to the lowest power level.

If the number of groups does not match the number of components exported by the device (by means of pm-components(9P) property), or the number of thresholds in a group is not one less than the number of power levels the corresponding component supports, then an error message will be printed and the entry will be ignored.

For example, assume a device called xfb exports the components Frame Buffer and Monitor. Component Frame Buffer has two power levels: Off and On. Component Monitor has four power levels: Off, Suspend, Standby, and On.

The following device-thresholds entry:

device-thresholds    /pci@f0000/xfb@0    (0) (3m 5m 15m)       

would set the threshold time for the Monitor component of the specific xfb card to go from On to Standby in 15 minutes, the threshold for Monitor to go from Standby to Suspend in 5 minutes, and the threshold for Monitor to go from Suspend to Off in 3 minutes. The threshold for Frame Buffer to go from On to Off will be 0 seconds.

In the second form above, where a single threshold value is specified without parentheses, the threshold value represents a maximum overall time within which the entire device should be powered down if it is idle. Because the system does not know about any internal dependencies there may be among a device's components, the device may actually be powered down sooner than the specified threshold, but will not take longer than the specified threshold, provided that all device components are idle.

In the third form above, all components of the device are left at full power.

Device Power Management entries are only effective if there is no user process controlling the device directly. For example, X Window systems directly control frame buffers and the entries in this file are effective only when X Windows are not running.

Dependencies among devices may also be defined. A device depends upon another if none of its components may have their power levels reduced unless all components of the other device are powered off. A dependency may be indicated by an entry of the form:

device-dependency   dependent_phys_path phys_path [ phys_path ... ] 

where dependent_phys_path is the path name (as above) of the device that is kept up by the others, and the phys_path entries specify the devices that keep it up. A symbolic link into the /devices tree (such as /dev/fb) is also accepted. This entry is needed only for logical dependents for the device. A logical dependent is a device that is not physically connected to the power managed device (for example, the display and the keyboard). Physical dependents are automatically considered and need not be included.

In addition to listing dependents by physical path, an arbitrary group of devices can be made dependent upon another device by specifying a property dependency using the following syntax:

device-dependency-property property phys_path [phys_path ...]

where each device that exports the property property will be kept up by the devices named by phys_path(s). A symbolic link into the /devices tree (such as /dev/fb) is accepted as well as a pathname for phys_path.

For example, the following entry:

# This entry keeps removable media from being powered down unless the
# console framebuffer and monitor are powered down
# (See removable-media(9P))
#
device-dependency-property removable-media /dev/fb

ensures that every device that exports the boolean property named removable-media will be kept up when the console framebuffer is up. (See removable-media(9P).)

An autopm entry may be used to enable or disable automatic device Power Management on a system-wide basis. The format of the autopm entry is:

autopmvbehavior

Acceptable behavior values and their meanings are:

default

The behavior of the system will depend upon its model. Desktop models that fall under the United States Environmental Protection Agency's Energy Star Memorandum of Understanding #3 will have automatic device Power Management enabled, and all others will not. See the NOTES section of this manual page for more information.

enable

Automatic device Power Management will be started when this entry is encountered.

disable

Automatic device Power Management will be stopped when this entry is encountered.

The system Power Management entries control power management of the entire system using the suspend-resume feature. When the system is suspended, the complete current state is saved on the disk before power is removed. On reboot, the system automatically starts a resume operation and the system is restored to the state it was in prior to suspend.

The system can be configured to do an automatic shutdown ( autoshutdown) using the suspend-resume feature by an entry of the following form:

autoshutdown idle_time start_time finish_time behavior

idle_time specifies the time in minutes that system must have been idle before it will be automatically shutdown. System idleness is determined by the inactivity of the system and can be configured as discussed below.

start_time and finish_time (each in hh:mm) specify the time period during which the system may be automatically shutdown. These times are measured from the start of the day (12:00 a.m.). If the finish_time is less than or equal to the start_time, the period span from midnight to the finish_time and from the start_time to the following midnight. To specify continuous operation, the finish_timemay be set equal to the start_time.

Acceptable behavior values and their meanings are:

shutdown

The system will be shut down automatically when it has been idle for the number of minutes specified in the idle_time value and the time of day falls between the start_time and finish_time values.

noshutdown

The system is never shut down automatically.

autowakeup

If the hardware has the capability to do autowakeup, the system is shut down as if the value were shutdown and the system will be restarted automatically the next time the time of day equals finish_time.

default

The behavior of the system will depend upon its model. Desktop models that fall under the United States Enviromental Protection Agency's Energy Star Memorandum of Understanding #2 will have automatic shutdown enabled (as if behavior field were set to shutdown), and all others will not. See NOTES.

unconfigured

The system will not be shut down automatically. If the system has just been installed or upgraded, the value of this field will be changed upon the next reboot.

You can use the following format to configure the system's notion of idleness:

idleness_parameter value

Where idleness_parameter can be:

ttychars

If the idleness_parameter is ttychars, the value field will be interpreted as the maximum number of tty characters that can pass through the ldterm module while still allowing the system to be considered idle. This value defaults to 0 if no entry is provided.

loadaverage

If the idleness_parameter is loadaverage, the (floating point) value field will be interpreted as the maximum load average that can be seen while still allowing the system to be considered idle. This value defaults to 0.04 if no entry is provided.

diskreads

If the idleness_parameter is diskreads, the value field will be interpreted as the maximum number of disk reads that can be perform by the system while still allowing the system to be considered idle. This value defaults to 0 if no entry is provided.

nfsreqs

If the idleness_parameter is nfsreqs, the value field will be interpreted as the maximum number of NFS requests that can be sent or received by the system while still allowing the system to be considered idle. Null requests, access requests, and getattr requests are excluded from this count. This value defaults to 0 if no entry is provided.

idlecheck

If the idleness_parameter is idlecheck, the value must be pathname of a program to be executed to determine if the system is idle. If autoshutdown is enabled and the console keyboard, mouse, tty, CPU (as indicated by load average), network (as measured by NFS requests) and disk (as measured by read activity) have been idle for the amount of time specified in the autoshutdown entry specified above, and the time of day falls between the start and finish times, then this program will be executed to check for other idleness criteria. The value of the idle time specified in the above autoshutdown entry will be passed to the program in the environment variable PM_IDLETIME. The process must terminate with an exit code that represents the number of minutes that the process considers the system to have been idle.

There is no default idlecheck entry.

When the system is suspended, the current system state is saved on the disk in a statefile. An entry of following form can be used to change the location of statefile:

statefile pathname  

where pathname identifies a block special file,for example, /dev/dsk/c1t0d0s2, or is the absolute pathname of a local ufs file. If the pathname specifies a block special file, it can be a symbolic link as long as it does not have a file system mounted on it. If pathname specifies a local ufs file, it cannot be a symbolic link. If the file does not exist, it will be created during the suspend operation. All the directory components of the path must already exist.

The actual size of statefile depends on a variety of factors, including the size of system memory, the number of loadable drivers/modules in use, the number and type of processes running, and the amount of user memory that has been locked down. It is recommended that statefile be placed on a file system with at least 10 Mbytes of free space. In case there is no statefile entry at boot time, an appropriate new entry is automatically created by the system.

prtconf -pv | grep -i energystar