POWER_REQUEST_TYPE - NtDoc
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// ntpoapi.h
typedef enum _POWER_REQUEST_TYPE {
PowerRequestDisplayRequired,
PowerRequestSystemRequired,
PowerRequestAwayModeRequired,
PowerRequestExecutionRequired
} POWER_REQUEST_TYPE, *PPOWER_REQUEST_TYPE;
View the official Windows Driver Kit DDI reference// wdm.h
typedef enum _POWER_REQUEST_TYPE {
PowerRequestDisplayRequired,
PowerRequestSystemRequired,
PowerRequestAwayModeRequired,
PowerRequestExecutionRequired
} POWER_REQUEST_TYPE, *PPOWER_REQUEST_TYPE;
View the official Windows Driver Kit DDI referenceNo description available.
The POWER_REQUEST_TYPE enumeration indicates the power request type.
PowerRequestDisplayRequiredNot used by drivers. For more information, see Remarks.
PowerRequestSystemRequiredPrevents the computer from automatically entering sleep mode after a period of user inactivity.
PowerRequestAwayModeRequiredNot used by drivers. For more information, see Remarks.
PowerRequestExecutionRequiredNot used by drivers. For more information, see Remarks.
This enumeration is used by the kernel-mode PoClearPowerRequest and PoSetPowerRequest routines. Drivers that call these routines must specify the PowerRequestSystemRequired enumeration value.
The other three enumeration values—PowerRequestDisplayRequired, PowerRequestAwayModeRequired, and PowerRequestExecutionRequired—are not used by drivers. Applications specify these power request types in calls to the PowerSetRequest and PowerClearRequest functions.
A PowerRequestDisplayRequired power request has the following effects:
While a PowerRequestAwayModeRequired power request is in effect, if the user tries to put the computer into sleep mode (for example, by clicking Start and then clicking Sleep), the power manager turns off audio and video so that the computer appears to be in sleep mode, but the computer continues to run.
While a PowerRequestExecutionRequired power request is in effect, the calling process continues to run instead of being suspended or terminated by process lifetime management (PLM) mechanisms. When and how long the process is allowed to run depends on the operating system and power policy settings. This type of power request is supported starting with Windows 8.
The POWER_REQUEST_TYPE enumeration indicates the power request type.
PowerRequestDisplayRequiredNot used by drivers. For more information, see Remarks.
PowerRequestSystemRequiredPrevents the computer from automatically entering sleep mode after a period of user inactivity.
PowerRequestAwayModeRequiredNot used by drivers. For more information, see Remarks.
PowerRequestExecutionRequiredNot used by drivers. For more information, see Remarks.
This enumeration is used by the kernel-mode PoClearPowerRequest and PoSetPowerRequest routines. Drivers that call these routines must specify the PowerRequestSystemRequired enumeration value.
The other three enumeration values—PowerRequestDisplayRequired, PowerRequestAwayModeRequired, and PowerRequestExecutionRequired—are not used by drivers. Applications specify these power request types in calls to the PowerSetRequest and PowerClearRequest functions.
A PowerRequestDisplayRequired power request has the following effects:
After a period of user inactivity, the session display stays on and will not automatically turn off.
A screensaver will not automatically start after a period of user inactivity.
The session will not be automatically locked after a period of user inactivity. If the session is already locked when the driver sends the power request, the session remains locked.
A PowerRequestSystemRequired must be taken in addition to a PowerRequestDisplayRequired to ensure the display stays on and the system does not enter sleep for the duration of the request.
While a PowerRequestAwayModeRequired power request is in effect, if the user tries to put the computer into sleep mode (for example, by clicking Start and then clicking Sleep), the power manager turns off audio and video so that the computer appears to be in sleep mode, but the computer continues to run. This is only applicable on Traditional Sleep (S3) systems.
While a PowerRequestExecutionRequired power request is in effect, the calling process continues to run instead of being suspended or terminated by process lifetime management (PLM) mechanisms. When and how long the process is allowed to run depends on the operating system and power policy settings. This type of power request is supported starting with Windows 8.
On Modern Standby systems on DC power, power requests are terminated after 5 minutes.
Except for PowerRequestAwayModeRequired on Traditional Sleep (S3) systems, power requests are terminated upon user-initiated system sleep entry (power button, lid close or selecting Sleep from the Start menu).