PoSetSystemState function (wdm.h)

Article
02/22/2024

Drivers call the PoSetSystemState routine to indicate that the system is active.

Syntax

void PoSetSystemState(
  [in] EXECUTION_STATE Flags
);

Parameters

[in] Flags

Indicates the system activity, as specified by a bitwise OR of one or more of the following values:

ES_SYSTEM_REQUIRED

The system is not idle, regardless of apparent load.

ES_DISPLAY_REQUIRED

Use of the display is required.

ES_USER_PRESENT

A user is present.

Return value

None

Remarks

A driver calls PoSetSystemState to set flags indicating that system activity is occurring. Unlike PoRegisterSystemState, this routine does not allow the driver to set a persistent busy state.

The Flags parameter specifies the type of activity occurring. Drivers can specify any combination of the flags.

Drivers can set the system busy state to request that the system avoid leaving of the working state while driver activity is occurring. Note, however, that under some circumstances (such as a critically low battery) the power manager may override this request and put the system to sleep anyway.

Requirements

Requirement	Value
Minimum supported client	Available starting with Windows 2000.
Target Platform	Universal
Header	wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	<=DISPATCH_LEVEL