IBM 86884RX Installation Guide - Page 20

a USB key, is to be implemented. First the BIOS would have to offer an option to, Consider

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In comparison to a BIOS-based, legacy system, the EFI is an additional layer between the operating system and the firmware. In a legacy system, the OS loader calls BIOS functions directly. Consequently, to provide a stable boot environment, changes in the OS loader and the platform firmware must go hand-in-hand. Note: All operating systems supported on x450 are EFI-aware. The OS loader communicates with the firmware and hardware through the EFI interface. The primary goal of this specification is to provide an abstract model both for operating system and hardware developers. With such a model in a place, OS loader customizations are not required if there are changes in the platform hardware or firmware (added new boot or input devices for instance). The EFI breaks up a tight dependency between the operating system and the firmware, thus speeding up the process of releasing the new products and introducing the new features and functionality (both operating system and hardware). Legacy OS loader Operating system EFI OS loader EFI Platform-specific firmware (BIOS) Platform hardware Figure 1-3 The EFI concept Consider, for example, the situation where a new type of boot device, for example a USB key, is to be implemented. First the BIOS would have to offer an option to choose this new device for booting, then new USB key-specific functions would have to be added to the firmware to support booting from a USB device, and finally, the OS loader would have to be modified to use these functions. 6 IBM ^ xSeries 450 Planning and Installation Guide

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6
IBM
^
xSeries 450 Planning and Installation Guide
In comparison to a BIOS-based, legacy system, the EFI is an additional layer
between the operating system and the firmware. In a legacy system, the OS
loader calls BIOS functions directly. Consequently, to provide a stable boot
environment, changes in the OS loader and the platform firmware must go
hand-in-hand.
The primary goal of this specification is to provide an abstract model both for
operating system and hardware developers. With such a model in a place, OS
loader customizations are not required if there are changes in the platform
hardware or firmware (added new boot or input devices for instance). The EFI
breaks up a tight dependency between the operating system and the firmware,
thus speeding up the process of releasing the new products and introducing the
new features and functionality (both operating system and hardware).
Figure 1-3
The EFI concept
Consider, for example, the situation where a new type of boot device, for example
a USB key, is to be implemented. First the BIOS would have to offer an option to
choose this new device for booting, then new USB key-specific functions would
have to be added to the firmware to support booting from a USB device, and
finally, the OS loader would have to be modified to use these functions.
Note:
All operating systems supported on x450 are EFI-aware. The OS loader
communicates with the firmware and hardware through the EFI interface.
Operating system
Platform-specific firmware (BIOS)
Platform hardware
Legacy OS
loader
EFI OS loader
EFI