PoSetSystemWake function (wdm.h)

The PoSetSystemWake routine marks the specified IRP as one that contributed to waking the system from a sleep state.

Syntax

void PoSetSystemWake(
  [in, out] PIRP Irp
);

Parameters

[in, out] Irp

A pointer to the wait/wake IRP.

Return value

None

Remarks

Drivers call PoSetSystemWake to mark an IRP_MN_WAIT_WAKE IRP as contributing to waking the system from a sleep state. By default, wait/wake IRPs are considered to be device wake-up IRPs. It is the responsibility of the terminal device in a wait/wake chain to determine if it woke the system and to call PoSetSystemWake for the terminal wait/wake IRP. When a driver calls PoSetSystemWake on an IRP, it is marked as having contributed to waking the system from a sleep state. Only one driver in a stack needs to call this routine, and it should normally be the bus driver in a driver stack.

All other drivers in a wait/wake chain can call PoGetSystemWake for their own wait/wake IRPs at completion to determine if they should call PoSetSystemWake on any child wait/wake IRPs that they are about to complete. This ensures that system wake information properly progresses throughout the wait/wake chain.

After a wait/wake IRP completes, the power manager checks if the IRP is marked as a system wake IRP. If the IRP is marked as a system wake IRP, the power manager adds the IRP to an internal list of the devices that woke the system. However, the power manager only keeps track of the most specific devices that work the system. For example, if device A is added as a device that woke the system, and then device B—a child of device A—is also added, the power manager only retains device B in the list because device B is the most specific. If the power manager cannot determine the most specific device that woke the system, the power manager might keep track of more than one device that reported it woke the system.

The power manager logs an Event Tracing for Windows (ETW) event (viewable in the global system channel) that includes information about which devices woke the system.

Requirements

See also

PoGetSystemWake