Intel Extensible Firmware Interface - Manual (Page 132)

Extensible Firmware Interface Specification
5-34 12/01/02 Version 1.10
OM13156
Device Handle
GUID
Interface
Protocol
Interface
Instance
Data
GUID
Interface
Protocol
Interface
Instance
Data
Device Handle
GUID
Interface
Protocol
Interface
Instance
Data
Image Handle
Controller Handle
Attributes
First Handle
Image Handle
Controller Handle
Attributes
Image Handle
Controller Handle
Attributes
Image Handle
Controller Handle
Attributes
Image Handle
Controller Handle
Attributes
Image Handle
Controller Handle
Attributes
Figure 5-2. Handle Database
In order to maintain these agent lists in the handle database, some new boot services are required.
These are
OpenProtocol() , CloseProtocol() , and OpenProtocolInformation() .
OpenProtocol() adds elements to the list of agents consuming a protocol interface.
CloseProtocol() removes elements from the list of agents consuming a protocol interface,
and OpenProtocolInformation() retrieves the entire list of agents that are currently using a
protocol interface.