请教Kbfiltr的IOCTL的问题

在做键盘过滤驱动的时候，想用DeviceIoControl函数操作键盘的IOCTL的时候，老不成功，在看Kbfiltr_IOCTL前面那段说明
    // If you are planning on using this function, you must create another
    // device object to send the requests to.  Please see the considerations
    // comments for KbFilter_DispatchPassThrough for implementation details.
    //
    // DriverObject->MajorFunction [IRP_MJ_DEVICE_CONTROL] = KbFilter_IoCtl;
是什么意思，那位老大做过，帮忙一下吧