8. Protocols - Device Path Protocol

8.1. Introduction

This section adds two device path node types that describe files stored in firmware volumes:

  • Firmware File Media Device Path

  • Firmware Volume Media Device Path

These device path nodes are used by a DXE-aware updated UEFI Boot Service LoadImage() to load UEFI images from firmware volumes. This new capability is used by the DXE Dispatcher to load DXE drivers from firmware volumes.

8.2. Firmware Volume Media Device Path

This type is used by systems implementing the PI architecture specifications to describe a firmware volume.

Table 8.2 Firmware Volume Media Device Path

Mnemonic

Byte Offset

Byte Length

Description

Type

0

1

Type 4 – Media Device Path

Sub-Type

1

1

Sub Type 7 – Firmware Volume Media Device Path

Length

2

2

Length of this structure in bytes. Length is 20 bytes

Firmware Volume Name

4

16

Firmware volume name. Type EFI_GUID

Table 8.3 Firmware Volume Device Node Text Representation

Device Node Type/Subtype/Other

Description

Type: 4 (Media Device Path)
Sub Type: 7 (Firmware Volume)
Fv (fv guid)
The fv guid is a GUID.

8.3. Firmware File Media Device Path

This type is used by systems implementing the PI architecture specifications to describe a firmware file in a firmware volume.

Table 8.4 Firmware File Media Device Path

Mnemonic

Byte Offset

Byte Length

Description

Type

0

1

Type 4 – Media Device Path

Sub-Type

1

1

Sub Type 6 – Firmware File Media Device Path

Length

2

2

Length of this structure in bytes. Length is 20 bytes.

Firmware File Name

4

16

Firmware file name. Type EFI_GUID.

Table 8.5 Firmware Volume File Device Node TextRepresentation

Device Node Type/Subtype/Other

Description

Type: 4 (Media Device Path)
Sub Type: 6 (Firmware File)
FvFile (fvfile-guid)
The fvfile guid is a GUID.