Dell PowerEdge M710 - Manual (Page 4)

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History
In the mid‐1990s during the development of Intel’s Itanium‐based system, PC BIOS limitations (for example, 16‐bit
processor mode, 1 MB addressable space, PC AT hardware dependencies, etc.) hindered platform development for
Itanium. While the Itanium chip was not well received, the development exposed significant limitations to the
original PC firmware architecture that led to the development of a new framework, called Extensible Firmware
Interface (EFI).
In 2005, several leading tech companies came together to create the EFI Forum. Based on EFI architecture, the
UEFI Forum’s mission was to create the first ever industry standard firmware interface specification – Unified
Extensible Firmware Interface (UEFI). Dell is represented on the board of directors of the UEFI Forum.
What is UEFI?
The UEFI specification defines an interface between operating systems and platform firmware. The interface
consists of data tables that contain platform‐related information, plus boot and runtime service calls that are
available to the operating system and its loader.
Together, these provide a standard, modern
environment for booting an operating system and
running pre‐boot applications
.
In addition to the services, UEFI defines various
protocols/APIs to access various hardware and the
boot devices in the system. The UEFI specification also
defines a driver model that is generic and can be
adapted to any type of bus or device. The UEFI Driver
Model is designed to support the execution of
modular pieces of code, known as drivers, that run in
the preboot environment. These drivers may manage
or control hardware buses and devices on the
platform, or they may provide some software‐derived,
platform‐specific service.
There are 3 types of entities that can execute under UEFI environment:
• Applications: Some examples of common EFI applications include the EFI shell, EFI shell
commands, flash utilities, and diagnostic utilities. It is perfectly acceptable to invoke EFI
applications from inside other EFI applications.
• Operating System Loader: A special type of EFI application, called an operating system boot
loader, provides the necessary initialization routines until the this loader has set up enough of
the operating system infrastructure to be ready to assume ownership of the system resources.
Once the operating system assumes control, the EFI core frees all of its boot time services and
drivers, leaving only the run‐time services and drivers.
• Drivers: EFI drivers differ from EFI applications in that the driver stays resident in memory unless
an error is returned from the driver's entry point. The EFI core firmware, the boot manager, or
other EFI applications may load drivers.