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DriverEntry routine

DriverEntry is the first routine called after a driver is loaded, and is responsible for initializing the driver.

Syntax


DRIVER_INITIALIZE DriverEntry;

NTSTATUS DriverEntry(
  _In_  struct _DRIVER_OBJECT *DriverObject,
  _In_  PUNICODE_STRING RegistryPath
)
{ ... }

Parameters

DriverObject [in]

A pointer to a DRIVER_OBJECT structure. This is the driver's driver object.

RegistryPath [in]

A pointer to a counted Unicode string specifying the path to the driver's registry key.

Return value

If the routine succeeds, it must return STATUS_SUCCESS. Otherwise, it must return one of the error status values defined in Ntstatus.h.

Remarks

The DriverObject parameter supplies the DriverEntry routine with a pointer to the driver's driver object, which is allocated by the I/O manager. The DriverEntry routine must fill in the driver object with entry points for the driver's standard routines.

The DriverObject pointer gives the driver access to DriverObject->HardwareDatabase, which points to a counted Unicode string that specifies a path to the registry's \Registry\Machine\Hardware tree.

The registry path string pointed to by RegistryPath is of the form \Registry\Machine\System\CurrentControlSet\Services\DriverName. A driver can use this path to store driver-specific information; see Registry Keys for Drivers. The DriverEntry routine should save a copy of the Unicode string, not the pointer, since the I/O manager frees the RegistryPath buffer after DriverEntry returns.

For more information about implementing a DriverEntry routine, see Writing a DriverEntry Routine.

While it is possible to name this routine something other than DriverEntry, doing so is not recommended. The DDK-supplied build tools automatically inform the linker that the driver's entry point is called DriverEntry, so giving the routine another name requires you to modify the build tools. For more information about build tools, see Building a Driver.

Examples

To define a DriverEntry callback routine, you must first provide a function declaration that identifies the type of callback routine you're defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it's a requirement for writing drivers for the Windows operating system.

To define a DriverEntry callback routine, use the DRIVER_INITIALIZE type as shown in this code example:


DRIVER_INITIALIZE DriverEntry;

Then, implement your callback routine as follows:



_Use_decl_annotations_
NTSTATUS 
  DriverEntry( 
    struct _DRIVER_OBJECT  *DriverObject,
    PUNICODE_STRING  RegistryPath 
    )
  {
      // Function body
  }

The DRIVER_INITIALIZE function type is defined in the Wdm.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the _Use_decl_annotations_ annotation to your function definition. The _Use_decl_annotations_ annotation ensures that the annotations that are applied to the DRIVER_INITIALIZE function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for WDM Drivers. For information about _Use_decl_annotations_, see Annotating Function Behavior.

Requirements

Header

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

IRQL

Called at PASSIVE_LEVEL.

See also

DRIVER_OBJECT

 

 

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