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Introduction to WMI for KMDF Drivers

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[Applies to KMDF only]

Kernel-Mode Driver Framework supports drivers that provide information to Windows Management Instrumentation (WMI). Such drivers are called WMI data providers because they provide data to WMI clients, which are applications that have registered to receive information from WMI.

WMI data providers support WMI data blocks, which can represent one or more of the following:

  • Data items, which contain device-specific data that a driver sends to, or receives from, a WMI client.

  • Methods (functions) that the driver executes on behalf of a WMI client.

  • Events that the driver sends to WMI clients that have registered to receive notification of device-specific events.

WMI data blocks are specified as WMI classes in .mof files. Each WMI data block is identified by a GUID.

All drivers must support any standard WMI data blocks that WMI defines for their device class. These WMI data blocks are defined in Wmicore.mof.

Your driver can also support WMI data blocks that you define in a .mof file. To learn how to define and publish customized WMI data blocks, see the following sections:

Framework WMI Objects and Callback Functions

The framework defines two objects that drivers can use to implement WMI data providers. The WMI provider object represents the schema for WMI data blocks that the driver provides. The WMI instance object represents an instance of a data block that is associated with a particular provider. Drivers communicate with WMI clients by implementing the following event callback functions that these two objects define:

EvtWmiProviderFunctionControl
Enables and disables the driver's support for collecting WMI data and sending WMI events.

EvtWmiInstanceQueryInstance
Delivers a WMI provider's instance data to a WMI client.

EvtWmiInstanceSetInstance and EvtWmiInstanceSetItem
Set information in a driver's data block to client-supplied values.

EvtWmiInstanceExecuteMethod
Executes a driver-supplied method, at the request of a client.

Sample Drivers that Implement WMI

The FIREFLY, PCIDRV, and Toaster sample drivers are WMI data providers.