EFI
CHAPTER 9 EFI Overview
9.1Boot Function
The EFI loads the different types of EFI drivers required for boot processing and, initialize those drivers.
EFI Boot Manager (hereafter called "Boot Manager") automatically executes boot processing according to preset boot information.
This boot information is set in advance by the installer and stored in the NVRAM variables of the EFI.
9.1.1NVRAM variables for boot control
This section describes the NVRAM variables that control boot processing.
(1) Boot#### variable
Information about the OS loader booted by Boot Manager is stored in this variable.
The information is stored in the EFI_LOAD_OPTION format as shown below. The
####part of the variable represents a displayable string of hexadecimal numbers ranging from 0000 to FFFF.
EFI_LOAD_OPTION Descriptor
UINT32 | Attributes ; |
UINT16 | FilePathListLength ; |
CHAR16 | Description[] ; |
EFI_DEVICE_PATH | FilePathList[] ; |
UINT8 | OptionalData [] ; |
(2) Driver#### variable
Information about the drivers loaded immediately before booting by Boot Manager is stored in this variable.
The information is stored in the EFI_LOAD_OPTION format as shown above. The
####part of the variable represents a displayable string of hexadecimal numbers ranging from 0000 to FFFF.
(3)BootOrder variable
This variable specifies the actual boot sequence of the target programs specified by the Boot#### variable.