Acronyms and Glossary

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Member-FAQ The EFI and Framework Open Source Community lives within a fairly complex world of acronyms, terms, etc. Hopefully this page helps clarify some of those and provides a good reference.

Advanced Configuration and Power Interface. See
Afterlife phase. Also known as the "power down phase."
ACPI Machine Language
Application Program Interface. Programmatic interfaces for the firmware (not Win32-type OS-level APIs).
a priori file
A file with a known GUID that contains the list of DXE drivers that are loaded and executed in the listed order before any other DXE drivers are discovered.
Something tracked in Project Tracker
ACPI Source Language
A field of something tracked in CEE Project Tracker
Boot Authorization
BIOS Boot Specification
Boot Device Selection phase
Boot Firmware Volume. Code (i.e., PEI and PEIM code) that appears in the memory address space of the system without prior firmware intervention. See also FV.
Boot Integrity Services
Built-in self test
Block Transfer (pronounced "blit" as in "slit" or "flit"). A series of functions that form the basis of manipulation graphical data. The operation used to draw a rectangle of pixels on the screen.
Backus-Naur Form. A metasyntactic notation used to specify the syntax of programming languages, command sets, and the like
The device handle that corresponds to the device from which the currently executing image was loaded
The part of the firmware implementation that is responsible for implementing system boot policy. Although a particular boot manager implementation is not specified in this document, such code is generally expected to be able to enumerate and handle transfers of control to the available OS loaders as well as EFI applications and drivers on a given system. The boot manager would typically be responsible for interacting with the system user, where applicable, to determine what to load during system startup. In cases where user interaction is not indicated, the boot manager would determine what to load and, if multiple items are to be loaded, what the sequencing of such loads would be.
Boot Services
The collection of interfaces and protocols that are present in the boot environment. The services minimally provide an OS loader with access to platform capabilities required to complete OS boot. Services are also available to drivers and applications that need access to platform capability. Boot services are terminated once the OS takes control of the platform.
Berkeley Software Distribution
Boot Strap Processor - typically the processor that will execute SEC and PEI
Common Object File Format. An (originally) Unix *-based file format that is now recognized under several OSs. The format uses one or more header fields followed by the section data for the file
A traditional legacy BIOS with the POST and BIOS Setup code removed. Compatibility16 BIOS code executes in real mode
The combination of both EfiCompatibility and Compatibility16
Any IBV-provided SMM code to perform traditional functions that are not provided by EFI
Cyclic Redundancy Check. A fixed-size error checking code appended to the end of a block of data (file) that is based on the content of the file
Core Root-of-Trust Module
Compatibility Support Module. The combination of EfiCompatibility, CompatibilitySmm , and Compatibility16. Portion of the Framework that allows compatibility with non-EFI compliant operating systems to run on Framework firmware
Configuration Values Driven through Reset
Dependency expression. Code associated with each Framework driver that describes the dependencies that must be satisfied in order for that driver to run. Controls order of execution in a Framework dispatch of PEIM and DXE drivers
DispatchEntry Point
The entry point that the dispatcher invokes
Modular chunk of firmware code that supports chipset or platform features. bReusable in multiple system contexts
Driver Execution Environment phase
DXE Foundation
A set of intrinsic services and an execution mechanism for sequenced control of driver modules
DXE Services
Services, such as security services and driver services, that are usable by DXE drivers
EFI code that corresponds to EFI compatibility drivers, code that generates data for compatibility interfaces, or code that invokes compatibility services.
EFI Developer Kit
Eclipse Public License
Extensible Firmware Interface (EFI)
EFI is a specification that defines the interface between an operating system, option ROMs, and platform firmware. EFI was originally invented by Intel as the Intel(R) Itainum BIOS replacement. EFI is now owned by a industry non-profit collaborative trade organization called The UEFI Forum.
File Allocation Table
FAT32 File System Driver
Firmware Device. A persistent physical repository that contains firmware code and/or data and that may provide NVS. For the purposes of this architecture specification, the topology of bFDs should be abstracted via bFVs.
Firmware File System. A binary storage format that is well suited to firmware volumes. The abstracted model of the FFS is a flat file system
Firmware Device
See FD.
Firmware Volume
See FV.
Firmware Interface Tableb.( Itanium systems only)
A translation between Unicode weights and glyphs. This "M" and this "M" and this "M" represent the same weight but in different fonts
The core interoperability interfaces between modules and in the Framework
Floating Point Software Assist. (Itanium systems only)
short for Intel® Platform Innovation Framework for EFI
Firmware Store. The abstracted model of the FS is a flat "file system" where individual files are SUMs
There are one or more FVs in the FS. The FV containing the "reset vector" is known as the Boot Firmware Volume (BFV). A FV is a simple Flash File System that starts with a header and contains files that are named by a GUID. The file system is flat and does not support directories. Each file is made up of a series of sections that support encapsulation.
Global coherency domain. The address resources of a system as seen by a processor. It consists of both system memory and I/O space
The graphical representation of a single Unicode weight
Globally Unique IDentifier (GUID)
Globally Unique Identifier. A 128-bit value used to differentiate and name services and structures.
Human Interface Infrastructure. Repository of configuration and translation information for localization. Typically used with boot manager and shell to provide a localized user interface.
Hand-Off Block. A structure used to pass information from one boot phase to another (i.e., from the PEI phase to the DXE phase)
Independent BIOS Vendor
Internal Forms Representation. A binary encoding of forms-based display content and configuration information
Independent Hardware Vendor
Input Method Editor
Intrinsic Services
Services, such as security services and driver services, that remain available after the phase during which they are instantiated
Initial Program Load. An architectural PEIM to PEIM interface that starts the DXE phase
Intelligent Platform Management Interface
ISO 3166
An association between a country or region and a two or three character ASCII string
ISO 639-2
An association between a language or dialect and a three character ASCII string
Concepts by which an interface is made useful to users speaking different languages and from various cultures by adapting the interfaces to the user. "STOP" in English would be "ALTO" in Spanish and "СТОП" in Russian. Alphabetic on keyboards are local to the language and may be local to the country the keyboard is localized for. For example, a French keyboard in France is different from a French keyboard in Canada.
Machine Check Architecture
Module Development Environment
Non-maskable Iinterrupt
Nonvolatile Random Access Memory
Nonvolatile storage. Flash, EPROM, ROM, or other persistent store that will not go away once system power is removed
Original Device Manufacturer
Original Equipment Manufacturer
Option ROM
Processor Abstraction Layer. A binary distributed by Intel that is used by the 64 bit Itanium processor family
Peripheral Component Interconnect. See for more information.
Platform Configuration Register
PE32, PE32+, or Common Object File Format. A defined standard file format for binary images
Pre-EFI Initialization phase. Set of drivers usually designed to initialize memory and the cpu so that DXE phase can run. sually the first bset of code run starting from reset.
PEI Foundation
A set of intrinsic services and an execution mechanism for sequenced control of PEIMs
Pre EFI Initialization Module (PEIM)
Pre-EFI Initialization Module. Modular chunk of firmware code running in PEI that supports chipset or platform features. Reusable in multiple system contexts.
PEI Services
Common services that are usable by PEIMs
PEIM to PEIM Interface (PPI)
A C structure named by a GUID that is published by one PEIM and consumed by another. The C structure can contain data and member functions. It differs from a Protocol in that it may have to function prior to memory being available and parts of the PPI could be in read only memory.
Phase Handoff Information Table. A HOB that describes the physical memory used by the PEI phase and the boot mode discovered during the PEI phase.
Position-independent code. Code that can be executed at any address without relocation
Power On Self Test
A C structure named by a GUID that is published by one EFI or DXE driver and consumed by another. The C structure can contain data and member functions.
Reverse Thunk
The code to transition from 16-bit real mode to native execution mode
ACPI definition: Root System Description Pointer
RT or Runtime phase
For EFI and the Framework this is after exit boot services has executed and the OS is in control of the system.
Runtime Services
Interfaces that provide access to underlying platform-specific hardware that may be useful during OS runtime, such as time and date services. These services become active during the boot process but also persist after the OS loader terminates boot services.
System Abstraction Layer. (Itanium systems only)
System Abstraction Layer entry point. (Itanium systems only)
The common properties of a driver or preboot environment that allow applications to run. These properties include a defined load image format and services that can run in the sandbox.
SECurity Phase. Initial starting point for boot process, first code executed after hardware reset. Responsible for 1) Establishing root trust in the software space; 2) Initializing architecture specific configuration to establish memory space for the C code stack.
System Management Interrupt
System Management Mode
Schedule on Request
Streaming SIMD Extensions
Separately Updateable Module. A portion of the BFV that is treated as a separate module that can be updated without affecting the other SUMs in the BFV.
Codename for the Intel Project to develop the Framework
Trusted Computing Base
Trusted Computing Group
TE Image
Terse Executable image. An executable image format that is specific to the Framework. This format is used only in PEI and is used for storing executable images in a smaller amount of space than would be required by a full PE32+ image. Is a smaller more compact version of bPE32.
The code to transition from native execution mode to 16-bit real mode
Universal Network Driver Interface. Silicon specific driver in the preboot LAN stack that interfaces to SNP and PXEBC
A standard defining an association between numeric values known as "weights" and characters from the majority of the worlds currently used languages. See the Unicode specification for more information.
Universal Serial Bus. See for more information
Visual Forms Representation. A high-level language representation of IFR
Virtual Machine
Volume Top File. A file in a firmware volume that must be located such that the last byte of the file is also the last byte of the firmware volume
A serial protocol definition that extends VT-100 to support Unicode
Watchdog Timer
An alarm timer that may be set to go off. This can be used to regain control in cases where a code path in the boot services environment fails to or is unable to return control by the expected path.
Execute In Place. PEI code that is executed from its storage location in a firmware volume

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