WDM Driver Loading Mode understanding

When the PC learns that a new device is plugged in, the bus driver creates the corresponding physical drive PDO and then prompts for a new device insertion, which calls the AddDevice method of the corresponding driver to create a function-driven FDO

The following is a typical AddDevice method

#pragmaPagedcodeNTSTATUS Hellowdmadddevice (in Pdriver_object driverobject, in Pdevice_object Physicaldeviceo    bject) {Paged_code (); Kdprint (("Enter hellowdmadddevice\n"));    NTSTATUS status;    Pdevice_object Fdo;    Unicode_string Devname; Rtlinitunicodestring (&devname,l"\\Device\\MyWDMDevice"); Status=IoCreateDevice (DriverObject,sizeof(device_extension),&(unicode_string) devname, File_device_unknown,0, FALSE,&FDO); if( !nt_success (status))returnstatus; Pdevice_extension PDX= (pdevice_extension) fdo->deviceextension; PDX->fdo =Fdo; PDX->nextstackdevice =IoAttachDeviceToDeviceStack (FDO, physicaldeviceobject);    Unicode_string Symlinkname; Rtlinitunicodestring (&symlinkname,l"\\DosDevices\\HelloWDM"); PDX->ustrdevicename =Devname; PDX->ustrsymlinkname =Symlinkname; Status= Iocreatesymboliclink (& (unicode_string) symlinkname,&(unicode_string) devname); if( !nt_success (status)) {Iodeletesymboliclink (&pdx->ustrsymlinkname); Status= Iocreatesymboliclink (&symLinkName,&devname); if( !nt_success (status)) {            returnstatus; }} FDO->flags |= Do_buffered_io |do_power_pagable; FDO->flags &= ~do_device_initializing; Kdprint (("Leave hellowdmadddevice\n")); returnstatus_success;}

The careful person may feel that this method's second parameter physicaldeviceobject, namely PDO, comes somewhat inexplicably, does not have the explanation type and so on

This object can specify its type in the INF, such as

Servicetype=1

WDM Driver Loading Mode understanding