Chapter 13 – Pre-EFI Initialization (PEI)

Small is Beautiful

—E.F. Schumacher

The UEFI Platform Initialization (PI) pre-EFI initialization (PEI) phase of execution has two primary roles in a platform’s life: determine the source of the restart and provide a minimum amount of permanent memory for the ensuing DXE phase. Words such as small and minimal are often used to describe PEI code because of hardware resource constraints that limit the programming environment. Specifically, the Pre-EFI Initialization (PEI) phase provides a standardized method of loading and invoking specific initial configuration routines for the processor, chipset, and system board. The PEI phase occurs after the Security (SEC) phase. The primary purpose of code operating ...

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