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Extensible Firmware Interface Specification
2-28 12/01/02 Version 1.10
2.6.1 Required Elements
Table 2-5 lists the required elements. Any system that is designed to conform to the EFI
specification must provide a complete implementation of all these elements. This means that all the
required service functions and protocols must be present and the implementation must deliver the
full semantics defined in the specification for all combinations of calls and parameters.
Implementers of EFI applications, drivers or operating system loaders that are designed to run on a
broad range of systems conforming to the EFI specification may assume that all such systems
implement all the required elements.
A system vendor may choose not to implement all the required elements, for example on
specialized system configurations that do not support all the services and functionality implied by
the required elements. However, since most EFI applications, drivers and operating system loaders
are written assuming all the required elements are present on a system that implements the EFI
specification; any such code is likely to require explicit customization to run on a less than
complete implementation of the required elements in the EFI specification.
Table 2-5. Required EFI Implementation Elements
Element Description
EFI System Table
Provides access to EFI Boot Services, EFI Runtime Services,
consoles, firmware vendor information, and the system
configuration tables.
EFI Boot Services All functions defined as boot services.
EFI Runtime Services All functions defined as runtime services.
LOADED_IMAGE protocol Provides information on the image.
DEVICE_PATH protocol Provides the location of the device.
DECOMPRESS protocol Protocol interfaces to decompress an image that was
compressed using the EFI Compression Algorithm.
EBC Interpreter An EFI Byte Code Interpreter is required so EFI images compiled
to EFI Byte Code executables are guaranteed to function on all
EFI compliant platforms. The EBC Interpreter must also produce
the EBC protocol.