Device Path Protocol
Version 1.02 12/12/00 129
5.3.4.13 Vendor-Defined Messaging Device Path
Table 5-21. Vendor-Defined Messaging Device Path
Mnemonic
Byte
Offset
Byte
Length Description
Type 0 1 Type 3 – Messaging Device Path
Sub-Type 1 1 Sub-Type 10 – Vendor
Length 2 2 Length of this structure in bytes. Length is 20 + n bytes.
Vendor_GUID 4 16 Vendor-assigned GUID that defines the data that follows
Vendor Defined Data 20 nVendor-defined variable size data
The following two GUIDs are used with a Vendor-Defined Messaging Device Path to describe the
transport protocol for use with PC-ANSI and VT-100 terminals. Device paths can be constructed
with this node as the last node in the device path. The rest of the device path describes the physical
device that is being used to transmit and receive data. The PC-ANSI and VT-100 GUIDs define the
format of the data that is being sent though the physical device. Additional GUIDs can be
generated to describe additional transport protocols.
#define DEVICE_PATH_MESSAGING_PC_ANSI \
{ e0c14753-f9be-11d2-9a0c-0090273fc14d }
#define DEVICE_PATH_MESSAGING_VT_100 \
{ DFA66065-B419-11d3-9A2D-0090273FC14D }
5.3.5 Media Device Path
This Device Path is used to describe the portion of the medium that is being abstracted by a boot
service. An example of Media Device Path would be defining which partition on a hard drive was
being used.
5.3.5.1 Hard Drive
The Hard Drive Media Device Path is used to represent a partition on a hard drive. The master boot
record (MBR) that resides in the first sector of the disk defines the partitions on a disk. Partitions
are addressed in EFI starting at LBA zero. Partitions are numbered one through n. A partition
number of zero can be used to represent the raw hard drive.
The MBR Type is stored in the Device Path to allow new MBR types to be added in the future.
The Hard Drive Device Path also contains a Disk Signature and a Disk Signature Type. The disk
signature is maintained by the OS and only used by EFI to partition Device Path nodes. The disk
signature enables the OS to find disks even after they have been physically moved in a system.