Intel Extensible Firmware Interface, Specification

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Extensible Firmware Interface Specification
116 12/12/00 Version 1.02
4.5.1.2 Handoff State, Itanium-based Operating Systems
EFI uses the standard P64 C calling conventions that are defined for Itanium-based operating
systems. Figure 4-2 shows the stack after
ImageEntryPoint
has been called on Itanium-based
systems. The arguments are also stored in registers: out0 contains
EFI_HANDLE
and out1
contains the address of the
EFI_SYSTEM_TABLE
. The gp for the EFI Image will have been
loaded from the plabel pointed to by the
AddressOfEntryPoint
in the image’s header.
EFI_SYSTEM_TABLE *
EFI_HANDLE
Stack
SP + 8
SP
Location
out1
out0
Register
Figure 4-2. Stack after ImageEntryPoint Called, Itanium-based Systems
The SAL specification (see “Related Information” in Chapter 1) defines the state of the system
registers at boot handoff. The SAL specification also defines which system registers can only be
used after EFI boot services have been properly terminated.