UEFI on ThinkServer TS140 and TS440
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1.0 Overview
This paper Introduces and describes key features of the UEFI firmware implementation found on
the ThinkServer TS140 and TS440. It also describes the procedures for configuring the system to
install UEFI aware Operating Systems that take advantage of the new features available in the
UEFI standard.
2.0 What is UEFI
The Unified Extensible Firmware Interface (UEFI) specification describes an interface between
an Operating System and the system firmware. UEFI firmware replaces the basic input/output
system (BIOS), which has been in place for x86 personal computers and servers for decades, and
provides advantages not possible with the older technology.
At system power-on, BIOS identifies and initializes the system’s hardware devices (such as the
hard disk, video adapter, keyboard, and mouse). BIOS then loads the operating system from
local storage (floppy, hard disk, CD-ROM, USB) or network, and passes control to it. BIOS is
specific to the Intel x86 processor architecture, and it relies on the 16-bit "real mode" interface
supported by x86 processors.
UEFI defines a similar interface that operates between the operating system and the platform
firmware, but is standards based, and not specific to any processor architecture. UEFI provides
data tables that contain system information, plus boot and runtime services that are available to
the operating system and its loader.
The UEFI standard was preceded by Extensible Firmware Interface Specification (EFI), developed
by Intel in the mid-1990s to support the Itanium® class of processors. In 2005, the EFI standard
was contributed to the UEFI Forum Inc., which now manages and evolves the UEFI specification.
The UEFI Forum is an active standards body with many industry participants of which Lenovo is a
contributing member, and a member of the Board of Directors.
3.0 The Benefits of UEFI
A significant benefit of UEFI is that it is designed to overcome limitations imposed by the older
BIOS architecture. Because BIOS is limited to a 16-bit processor mode and 1 MB of addressable
space, space for advanced BIOS functionality is limited. Space for PCI option ROMs is also
limited, restricting the number of adapters that can be installed, and how much functionality
each Option ROM can contain. UEFI in comparison supports either 32-bit or 64-bit processor
modes. In 64-bit mode, UEFI applications in the pre-boot execution environment have direct
access to all of the memory in the system using 64-bit addressing.
BIOS systems also support only disks that use the master boot record (MBR) partitioning
scheme, which limits the maximum size of a disk to approximately 2.2 terabytes (TB), and a