Handling WMI Requests

All drivers must set a dispatch table entry point for a DispatchSystemControl routine to handle WMI requests. If a driver registers as a WMI data provider, it must handle all WMI requests. Otherwise, the driver must forward all WMI requests to the next lower driver.

All WMI IRPs have the major code IRP_MJ_SYSTEM_CONTROL and a one of the following minor codes:

• IRP_MN_REGINFO, IRP_MN_REGINFO_EX—Queries or updates a driver's registration information after the driver has called IoWMIRegistrationControl.

• IRP_MN_QUERY_ALL_DATA, IRP_MN_QUERY_SINGLE_INSTANCE—Queries for all instances or a single instance of a given data block.

• IRP_MN_CHANGE_SINGLE_ITEM, IRP_MN_CHANGE_SINGLE_INSTANCE—Requests the driver to change a single item or multiple items in an instance of a data block.

• IRP_MN_ENABLE_COLLECTION, IRP_MN_DISABLE_COLLECTION—Requests the driver to start accumulating data for a block that the driver registered as expensive to collect, or to stop accumulating data for such a block.

• IRP_MN_ENABLE_EVENTS, IRP_MN_DISABLE_EVENTS—Requests the driver to start sending notification of a given event if the event occurs while it is enabled, or to stop sending notification of such an event.

• IRP_MN_EXECUTE_METHOD—Requests the driver to execute a method associated with a data block.

The WMI kernel-mode component sends WMI IRPs any time following a driver's successful registration as a WMI data provider, typically when a user-mode data consumer has requested WMI information for a driver's device. If a driver registers as a WMI data provider by calling IoWMIRegistrationControl, it must handle each subsequent WMI request in one of the following ways:

• Call the kernel-mode WMI library routine WmiSystemControl. A driver can call WmiSystemControl to handle requests concerning only blocks that do not use dynamic instance names, and that base static instance names on a single base name string or the device instance ID of a PDO. For more information, see Calling WmiSystemControl to Handle WMI IRPs.

• In its DispatchSystemControl routine, process and complete any such request tagged with the pointer to its device object that the driver passed in its call to IoWMIRegistrationControl, and forward other IRP_MJ_SYSTEM_CONTROL requests to the next lower driver. For more information, see Processing WMI IRPs in a DispatchSystemControl Routine.

For a list of the WMI minor IRPs, see WMI Minor IRPs.