The PnP manager uses this IRP to get a device's resource requirements list.
Bus drivers must handle this request for their child devices that require hardware resources. Bus filter drivers can handle this request. Function and filter drivers do not handle this IRP.
The PnP manager sends this IRP when a device is enumerated, prior to allocating resources to a device, and when a driver reports that its device's resource requirements have changed.
The PnP manager sends this IRP at IRQL PASSIVE_LEVEL in an arbitrary thread context.
Returned in the I/O status block.
I/O Status Block
A driver that handles this IRP sets Irp->IoStatus.Status to STATUS_SUCCESS or an appropriate error status.
On success, a driver sets Irp->IoStatus.Information to a pointer to an IO_RESOURCE_REQUIREMENTS_LIST that contains the requested information. On an error, the driver sets Irp->IoStatus.Information to zero.
If a bus driver returns a resource requirements list in response to this IRP, it allocates an IO_RESOURCE_REQUIREMENTS_LIST from paged memory. The PnP manager frees the buffer when it is no longer needed.
If a device requires no hardware resources, the device's bus driver completes the IRP (IoCompleteRequest) without modifying Irp->IoStatus.Status or Irp->IoStatus.Information.
If a bus filter driver handles this IRP, it modifies the resource requirements list created by the bus driver. A bus filter driver modifies the list on the IRP's way back up the device stack. A bus filter driver must preserve the order of resources in the resource requirements list and must not alter resource tags that it does not handle. If a bus filter driver changes the size of the resource requirements list, the driver must allocate a new structure from paged memory and free the previous structure. If a bus filter driver adds a new resource requirement to the list and the resource is assigned to the device, the driver must filter the new resource out of the IRP_MN_START_DEVICE IRP so it is not passed to the bus driver.
Function and non-bus filter drivers do not handle this IRP; they pass it to the next lower driver with no changes to Irp->IoStatus.
Sending This IRP
Reserved for system use. Drivers must not send this IRP.