power.conf(4) File Formats power.conf(4)
power.conf - Power Management configuration information file
The power.conf file is used by the Power Management configuration program pmconfig(1M), to initialize the settings for Power Management. If
you make changes to this file, you must run pmconfig(1M) manually for the changes to take effect.
The dtpower(1M) GUI allows the configuration of a subset of parameters allowed by this file. For ease-of-use, it is recommended that you
use dtpower(1M) to configure the parameters. See the Examples section for information on disabling Power Management.
Power Management addresses two specific management scenarios: management of individual devices and management of the whole system. An indi-
vidual device is power managed if the device supports multiple power levels and if the device driver uses Power Management interfaces pro-
vided by the kernel to save device power when the device is idle.
All entries in the power.conf file are processed in the order that they occur in the file.
Automatic Device Power Management
Devices with drivers that use the automatic device Power Management interfaces are automatically power managed if the autopm entry is
enabled. The autopm entry is described near the end of this section. The pm-components property describes the Power Management model of a
device driver to the Power Management framework. See pm-components(9P) for more information.
When a component has been idle at a given power level for its threshold time, the power level of the component is 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 thresh-
old. 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:
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 are left at full power.
The system-threshold entry is applicable to CPU Power Management only when CPU Power Management has been configured to operate in poll-
mode, which is expressed through the cpupm keyword.
If a system has power manageable CPUs, these can be managed independently of the system idleness threshold by using one of the following
where threshold is the value of the CPU 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 CPUs are left at full power.
The cpu-threshold keyword is used only when CPU Power Management has been configured to operate in poll-mode, which is expressed through
the cpupm keyword.
If no cpu-threshold entry is specified, then the system idleness threshold is used.
To override the default device component thresholds assigned by the Power Management framework, a device-thresholds entry can be used. A
device-thresholds entry sets thresholds for a specific automatically power-managed device or disables automatic Power Management for the
A device-thresholds entry has the form:
device-thresholds phys_path (threshold ...) ...
device-thresholds phys_path threshold
device-thresholds hys_path always-on
where phys_path specifies the physical path (libdevinfo(3LIB)) 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 is 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, and the like. 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
is printed and the entry is 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 Suspendin 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 is 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 can be among a device's components, the device can actually be powered down sooner than the specified threshold, but does 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 Windows sys-
tems directly control frame buffers. The entries in the power.conf file are effective only when X Windows is not running.
Dependencies among devices can also be defined. A device depends upon another if none of its components might have their power levels
reduced unless all components of the other device are powered off. A dependency can 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 is 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 ensures that every device that exports the boolean property named removable-media is kept up when the con-
sole framebuffer is up. See removable-media(9P).
# 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
An autopm entry can be used to enable or disable automatic device Power Management on a system-wide basis. The format of the autopm entry
Acceptable behavior values are described as follows:
default The behavior of the system depends upon its model. Desktop models that fall under the United States Environmental Protection
Agency's Energy Star Memorandum of Understanding #3 have automatic device Power Management enabled, and all others do not. See
the Notes section of this manual page for more information.
enable Automatic device Power Management is started when this entry is encountered.
disable Automatic device Power Management is stopped when this entry is encountered.
A cpupm entry can be used to enable or disable Power Management of CPUs on a system-wide basis, independent of autopm. The format of the
cpupm entry is:
Acceptable behavior values and their meanings are :
enable CPU Power Management is started when this entry is encountered.
Where the behavior is enable, an optional mode argument can be specified:
cpupm enable mode
Acceptable mode values and their meanings are:
event-mode CPU power state transitions is driven by thread scheduler/dispatcher events. The cpu-threshold, and system-thresh-
old keywords are not used for CPUs in this mode.
poll-mode The Power Management framework polls the idleness of the system's CPUs, and manages their power once idle for the
period of time specified by either the system-threshold or cpu-threshold.
disable CPU Power Management is stopped when this entry is encountered.
If supported by the platform, a cpu_deep_idle entry can be used to enable or disable automatic use of power saving cpu idle states. The
format of the cpu_deep_idle entry is:
Acceptable values for behavior are:
default Advanced cpu idle power saving features are enabled on hardware which supports it. On X86 systems this can translate to the use
of ACPI C-States beyond C1.
enable Enables the system to automatically use idle cpu power saving features.
disable The system does not automatically use idle cpu power saving features. This option can be used when maximum performance is
required at the expense of power.
absent It the cpu_deep_idle keyword is absent from power.conf the behavior is the same as the default case.
Once every device is at its lowest possible power state, additional power savings can be obtained by putting the system into a sleep state
(if the platform hardware is capable of doing so).
Because of reliability problems encountered in BIOS implementations of X86 systems not produced by Sun Microsystems, by default, only X86
workstation products produced by Sun are considered to support S3 (suspend to RAM). To override this default, an S3-support entry (of the
format S3-support behavior) can be used to indicate if the system supports S3.
Acceptable behavior values are:
enable The system supports entry into S3 state. If the BIOS of a system enabled using an S3-support enable entry does not support entry
into S3, the attempt fails and the system returns to normal operation. If support for S3 in the BIOS of a system enabled via an
S3-support entry contains bugs, the system can be unable to enter S3 or resume successfully, so use this entry with caution.
disable The system does not support entry into S3 state.
Automatic Entry Into S3
If supported by your platform, an autoS3 entry can be used to enable or disable automatic entry into the S3 state. When in the S3 state,
the power button, keyboard and mouse activity or network traffic (depending upon the capabilities of the platform hardware) can wake the
system, returning it to the state it was in upon entry to the S3 state. If the platform doesn't support S3, the entry has no effect.
The format of the autoS3 entry is autoS3 behavior.
Acceptable behavior values are:
default System behavior depends upon model. Sun X86 desktop and workstation models that fall under the United States Environmental Pro-
tection Agency's Energy Star Memorandum of Understanding #3 have automatic entry into the S3 state enabled. Non-Sun systems do
not. See NOTES for more information.
enable Enables the system to automatically enter the S3 state if autopm is enabled and every device is at its lowest power state.
disable The system does not automatically enter the S3 state.
System Power Management
The system Power Management entries control Power Management of the entire system using the suspend-resume feature. When the system is sus-
pended, the complete current state is saved on the disk before power is removed. On reboot, the system automatically starts a resume opera-
tion 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 is 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 can 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_time can be set equal to
Acceptable behavior values are described as follows:
shutdown The system is 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
is restarted automatically the next time the time of day equals finish_time.
default The behavior of the system depends upon its model. Desktop models that fall under the United States Enviromental Protection
Agency's Energy Star Memorandum of Understanding #2 have automatic shutdown enabled, as if behavior field were set to shut-
down, and all others do not. See Notes.
unconfigured The system does not be shut down automatically. If the system has just been installed or upgraded, the value of this field
is changed upon the next reboot.
You can use the following format to configure the system's notion of idleness:
Where idleness_parameter can be:
ttychars If the idleness_parameter is ttychars, the value field is 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
loadaverage If the idleness_parameter is loadaverage, the (floating point) value field is 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 is interpreted as the maximum number of disk reads that can be per-
form 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 is 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 mea-
sured 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 is exe-
cuted to check for other idleness criteria. The value of the idle time specified in the above autoshutdown entry is 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:
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 is 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.
Example 1 Disabling Automatic Device Power Management
To disable automatic device Power Management, change the following line in the /etc/power.conf file
Then run pmconfig or reboot. See pmconfig(1M) for more information.
You can also use dtpower to disable automatic device Power Management. See dtpower(1M) for more information.
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|Availability |SUNWpmr |
|Interface stability |Committed |
pmconfig(1M), powerd(1M), sys-unconfig(1M), uadmin(2), libdevinfo(3LIB), attributes(5), cpr(7), ldterm(7M), pm(7D), pm-components(9P),
Writing Device Drivers
Solaris Common Desktop Environment: User's Guide
SPARC desktop models first shipped after October 1, 1995 and before July 1, 1999 comply with the United States Enviromental Protection
Agency's Energy Star Memorandum of Understanding #2 guidelines and have autoshutdownenabled by default after 30 minutes of system idleness.
This is achieved by default keyword of autoshutdown entry behave as shutdown for these machines. The user is prompted to confirm this
default behavior at system installation reboot, or during the first reboot after the system is unconfigured by sys-unconfig(1M).
SPARC desktop models first shipped after July 1, 1999 comply with the United States Enviromental Protection Agency's Energy Star Memorandum
of Understanding #3 guidelines and have autoshutdowndisabled by default, with autopm enabled after 30 minutes of idleness. This is achieved
by interpreting default keyword of autopm entry behavior as enabled for these machines. User is not prompted to confirm this default behav-
To determine the version of the EPA's Energy Star Memorandum applicable to your machine, use:
prtconf -pv | grep -i energystar
Absence of a property indicates no Energy Star guidelines are applicable to your machine.
System Power Management ( suspend-resume) is currently supported only on a limited set of hardware platforms. Please see the book Solaris
Common Desktop Environment: User's Guide for a complete list of platforms that support system Power Management. See uname(2) to programati-
cally determine if the machine supports suspend-resume.
Sun X86 desktop models first shipped after July 1, 1999 fall within United States Enviromental Protection Agency's Energy Star Memorandum
of Understanding #3 guidelines and have autopm and autoS3 enabled by default, with entry into S3 after 30 minutes of idleness. This is
achieved by interpreting the default keyword of the autopm and autoS3 behaviors as enabled for these machines. You are not prompted to con-
firm the default behavior. On all other X86 systems, the autopm and autoS3 default keywords are interpreted as disable.
SunOS 5.11 27 Feb 2009 power.conf(4)