Introduction to UEFI

To follow up on my previsou post on UEFI causing boot issues on IBM Servers.

This article is worth a read if working with the new UEFI firmware.

ftp://ftp.software.ibm.com/systems/support/system_x_pdf/introducing_uefi-compliant_fireware_on_ibm_system_x.1.1.pdf

Specifically interesting sections are Page 12:

Optimizing boot-time performance

The simplest way to achieve quicker boot times for a configuration is to install and boot UEFIaware operating systems whenever possible. For deployments in which a UEFI-aware operating

system is not available, this section introduces concepts and techniques for optimally configuring adapter support for legacy boots. The major variable determinants of server boot-time performance are how much memory capacity is available and what adapters are installed. Other determinants of boot-time performance are inherent to the design and core technologies of the server design (such as

CRTM/TPM, platform self-test, and power management) and are not configurable. Always usethe latest available firmware, because any optimizations to these core features will be in the latest firmware releases.

Memory

The more memory that is installed, the more there is to initialize ECC and test. You can install less memory, but that usually does not result in significant boot-time improvement. The best approach for optimizing boot time and memory use is to balance DIMMs and memory capacity across installed processors. Balancing memory optimizes memory initialization on servers with integrated memory controllers (such as Intel Xeon® 5500 based servers). For details, see the Optimizing the Performance of IBM System x and BladeCenter Servers using Intel Xeon 5500 Series Processors white paper.

Adapters

Some classes of server adapters, such as network or RAID controllers, can take considerable time to initialize in the pre-operating-system UEFI or BIOS environment. Because IBM System x Server Firmware simultaneously supports both UEFI and BIOS boot mechanisms, there can be unwanted repetition of adapter initialization when BIOS operating systems are booted. This repetition can occur with an adapter that includes native UEFI device drivers in addition to BIOS code on its adapter ROM. For suggested approaches to tuning adapter support for better boot-time performance, see “UEFI and BIOS adapter support details” and “Enabling and disabling adapter ROM support.”

Page 24 also advised how to disable adapters for UEFI.