All PnP drivers must handle this IRP.



Major Code


When Sent

The PnP manager sends this IRP after it has assigned hardware resources, if any, to the device. The device may have been recently enumerated and is being started for the first time, or the device may be restarting after being stopped for resource rebalancing.

Sometimes the PnP manager sends an IRP_MN_START_DEVICE to a device that is already started, supplying a different set of resources than the device is currently using. A driver initiates this action by calling IoInvalidateDeviceState and responding to the subsequent IRP_MN_QUERY_PNP_DEVICE_STATE request with the PNP_RESOURCE_REQUIREMENTS_CHANGED flag set. A bus driver might use this mechanism, for example, to open a new aperture on a PCI-to-PCI bridge.

The PnP manager sends this IRP at IRQL PASSIVE_LEVEL in the context of a system thread.

Input Parameters

The Parameters.StartDevice.AllocatedResources member of the IO_STACK_LOCATION structure points to a CM_RESOURCE_LIST describing the hardware resources that the PnP manager assigned to the device. This list contains the resources in raw form. Use the raw resources to program the device.

Parameters.StartDevice.AllocatedResourcesTranslated points to a CM_RESOURCE_LIST describing the hardware resources that the PnP manager assigned to the device. This list contains the resources in translated form. Use the translated resources to connect the interrupt vector, map I/O space, and map memory.

Output Parameters


I/O Status Block

A driver sets Irp->IoStatus.Status to STATUS_SUCCESS or to an appropriate error status such as STATUS_UNSUCCESSFUL or STATUS_INSUFFICIENT_RESOURCES.

If a driver requires some time to run its start operations for a device, it can mark the IRP pending and return STATUS_PENDING.


This IRP must be handled first by the parent bus driver for a device and then by each higher driver in the device stack.

In response to this IRP, drivers start a device for the first time or restart a device that was stopped. The exact operations required to start a device vary from device to device, but can include powering on the device, performing device-specific initialization, and connecting the interrupt.

A driver can typically handle this IRP in the same way whether it is starting a device for the first time or restarting a device after an IRP_MN_STOP_DEVICE, except if a driver needs to restore device state on a restart after a stop.

On Windows Vista and later operating systems, we recommend that drivers always pend the IRP_MN_START_DEVICE IRP and complete its processing later. This order enables the system to process device restarts asynchronously. (On operating systems before Windows Vista, drivers can return STATUS_PENDING from their dispatch routines, but the PnP manager does not overlap the device restart with any other operation.)

For more information about handling a start IRP, see Starting a Device.

Sending This IRP

Reserved for system use. Drivers must not send this IRP.



Wdm.h (include Wdm.h, Ntddk.h, or Ntifs.h)

See also