Extensible Firmware Interface Specification
246 12/12/00 Version 1.02
Description
The basic mechanisms and flow for remote booting in EFI are identical to the remote boot
functionality described in detail in the PXE Specification. However, the actual execution
environment, linkage, and calling conventions are replaced and enhanced for the EFI environment.
The DHCP Option for the Client System Architecture is used to inform the DHCP server if the
client is an IA-32 or Itanium-based EFI environment. The server may use this information to
provide default images if it does not have a specific boot profile for the client.
A handle that supports EFI_PXE_BASE_CODE protocol is required to support the LOAD_FILE
protocol. The LOAD_FILE protocol function LoadFile() is used by the firmware to load files
from devices that do not support file system type accesses. Specifically, the firmware’s boot
manager invokes LoadFile() with BootPolicy being TRUE when attempting to boot from
the device. The firmware then loads and transfers control to the downloaded PXE boot image.
Once the remote image is successfully loaded, it may utilize the EFI_PXE_BASE_CODE
interfaces, or even the EFI_SIMPLE_NETWORK interfaces, to continue the remote process.