Specifications

2
2
Design Discussion
2.1 Definitions of Terms
The following definitions, except where noted, are not EFI specific. See the master
Framework glossary for definitions of other Framework terms; see “Typographic
Conventions” later in this section for the URL.
16-bit legacy
The traditional PC environment and includes traditional OpROMs and
Compatibility16 code.
Compatibility16
The traditional BIOS with POST and BIOS Setup removed. Executes in 16-bit
real mode.
CompatibilitySmm
Any IBV-provided SMM code to perform traditional functions that are not
provided by EFI.
CSM
Compatibility Support Module. The combination of EfiCompatibility,
CompatibilitySmm, and Compatibility16.
EfiCompatibility
32-bit EFI code to generate data for traditional BIOS interfaces or EFI
Compatibility Support Module drivers, or code to invoke traditional BIOS
services.
IBV
Independent BIOS vendor.
NV
Nonvolatile.
OpROM
Option ROM.
PIC
Programmable Interrupt Controller.
PMM
Post Memory Manager.
reverse thunk
The code to transition from 16-bit real mode to native execution mode and
back.
SMM
System Management Mode.