Controller handle (Device handle)
Presents a physical device,
     must support the Device Path Protocol.
     Called Physical controller handle.
Presents a virtual device,
     must not support the Device Path Protocol.
     Called Virtual controller handle.

(只有Physical Device 會support Device Path Protocol.)

A device handle must support one or more additional I/O protocols
  that are used to abstract access to that device.
 
The primary purpose of a Device Path is to allow an application,
 such as an OS loader, to determine the physical device that the interfaces are abstracting.

 

There are six major types of Device Path nodes:


•  Hardware Device Path.  This Device Path defines how a device is attached to the resource
domain of a system, where resource domain is simply the shared memory, memory mapped
I/O, and I/O space of the system. 

在Industry Standard Bus 上的device,且能透過I/O space or Mem space 存取的device


•  ACPI Device Path.  This Device Path is used to describe devices whose enumeration is not
described in an industry-standard fashion.  These devices must be described using ACPI AML
in the ACPI name space; this Device Path is a linkage to the ACPI name space.  


•  Messaging Device Path.  This Device Path is used to describe the connection of devices outside
the resource domain of the system.  This Device Path can describe physical messaging
information (e.g., a SCSI ID) or abstract information (e.g., networking protocol IP addresses).

在Industry Standard Bus 上的device,但不能透過I/O space or Mem space 存取的device

而是透過別的方式存取,像是 USB  透過 PCI to USB Bridge 去存取...


•  Media Device Path.  This Device Path is used to describe the portion of a medium that is being
abstracted by a boot service.  For example, a Media Device Path could define which partition
on a hard drive was being used.

描述 partition 的


•  BIOS Boot Specification Device Path.  This Device Path is used to point to boot legacy
operating systems; it is based on the BIOS Boot Specification Version 1.01.  Refer to the
References appendix for details on obtaining this specification.


•  End of Hardware Device Path.  Depending on the Sub-Type, this Device Path node is used to
indicate the end of the Device Path instance or Device Path structure.

整個 Device Path 的結束識別

 

Device Path Protocol 是 Non Driver Modle Driver

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