Handling IRP_MN_REGINFO and IRP_MN_REGINFO_EX to Register Blocks

On Windows 98 and Windows 2000, the system sends the IRP_MN_REGINFO request to a driver to allow a driver to register its WMI classes. On Windows XP and later, the system sends the IRP_MN_REGINFO_EX request instead. Most drivers can handle these requests by using WmiSystemControl to provide a callback routine. See Using the WMI Library to Register Blocks for details.

A driver must handle IRP_MN_REGINFO or IRP_MN_REGINFO_EX requests to register blocks that use dynamic instance names or that use a list of driver-defined static instance names; it cannot call WmiSystemControl to register such blocks. A driver can optionally handle this request to register blocks that use static instance names based on the PDO or a driver-defined base name string.

In this case, the driver:

  1. Fills in a WMIREGINFO structure at Parameters.WMI.Buffer that specifies:

    • The number of bytes of all registration data supplied by the driver, including data supplied on behalf of another driver.

    • The driver's registry path.

    • The name of the driver's MOF resource.

    • The number of blocks to register.

    • An array of WMIREGGUID structures, one for each block.

  2. For each block, the driver fills in a WMIREGGUID structure that specifies:

    • The GUID that represents the block.

    • Flags that provide information about instance names and other characteristics of the block, such as whether the block is expensive to collect. For more information, see WMI Registration Flags.

    If the block is being registered with static instance names, the driver sets one of the following members to specify static instance name data for the block:

    • If the driver sets Flags with WMIREG_FLAG_INSTANCE_LIST, it sets InstanceNameList to an offset to a list of static instance name strings. WMI specifies instances in subsequent requests by index into this list.

    • If the driver sets Flags with WMIREG_FLAG_INSTANCE_BASENAME, it sets BaseNameOffset to an offset to a base name string. WMI uses this string to generate static instance names for the block.

    • If the driver sets Flags with WMIREG_FLAG_INSTANCE_PDO, it sets Pdo to the PDO passed to the driver's AddDevice routine. WMI uses the device instance path of the PDO to generate static instance names for the block. When handling an IRP_MN_REGINFO_EX request, drivers must call the ObReferenceObject routine on the physical device object passed in Pdo. (The system will automatically call ObDereferenceObject to dereference the object; the driver must not do so.)

    The driver writes instance name strings or a base name string at the offset indicated by InstanceNameList or BaseName, respectively.

  3. If the driver is registering blocks on behalf of another driver (as a class driver might on behalf of a miniclass driver), the driver fills in another WMIREGINFO structure and list of WMIREGGUID structures with registration information for the other driver's blocks, and sets NextWmiRegInfo in the first WMIREGINFO to the offset in bytes from the beginning of the first WMIREGINFO to the beginning of the second WMIREGINFO structure.

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