windows-xp/Source/XPSP1/NT/base/hals/halacpi/amd64/xmstub.asm

	title "Amd64 startup"

;++
;
; Copyright (c) 2001 Microsoft Corporation
;
; Module Name:
;
;    xmstub.asm
;
; Abstract:
;
;    This module implements the code that starts secondary processors.  This
;    module is unique in that it is assembled by the i386 32-bit assembler,
;    because the Amd64 assembler does not assemble 16- or 32-bit x86 code.
;
;    The .obj file that is the result of assembling this module is fed
;    through a tool, DMPOBJ.EXE, that stores the contents of the relevant
;    section and generates a c file (startup.c) that can be included in the
;    64-bit compilation process.
;
; Author:
;
;    Forrest Foltz (forrestf) March 6, 2001
;
; Environment:
;
;    Kernel mode only.
;
; Revision History:
;
;--

.586p

include ksamd64.inc

RMSTUB SEGMENT DWORD PUBLIC USE16 'CODE'

;++
;
; VOID
; StartPx_RMStub
;
;   When a new processor is started, it starts in real mode and is sent to a
;   copy of this function which resides in low (<1MB) memory.
;
;   When this function is complete, it jumps to StartPx_PMStub.
;
; Arguments:
;   None
;
; Return Value:
;   Does not return, jumps to StartPx_PMStub
;--

StartPx_RMStub:

	jmp	spr10			; skip the processor start block

	db (ProcessorStartBlockLength - ($ - StartPx_RMStub)) dup (0)

spr10:  cli
	mov	ax, cs
	mov	ds, ax

	;
	; Load the 32-bit GDT.
	; 

	db	066h
	lgdt	fword ptr ds:[PsbGdt32]

	;
	; Load edi with the linear address of the processor start block.
	;

        sub	eax, eax
	mov	ax,  ds
	shl	eax, 4
	mov	edi, eax

	;
	; Enter protected mode.  Note paging is still off.
	;

	mov	eax, cr0
	or	eax, CR0_PE OR CR0_ET
	mov	cr0, eax

	;
	; Load CS by performing a far jump to the protected mode target
	; address
	; 

	db	066h
	jmp	DWORD PTR ds:[PsbPmTarget]

RMSTUB ENDS

;++
;
; VOID
; StartPx_PMStub
;
;   When a new processor is started, it starts in real mode and is sent to a
;   copy of this function which resides in low (<1MB) memory.
;
;   When this function is complete, it jumps to StartPx_PMStub.
;
; Arguments:
;   None
;
; Return Value:
;   Does not return, jumps to StartPx_LMStub
;--


PMSTUB SEGMENT PARA PUBLIC 'CODE'

StartPx_PMStub:

	;
	; 32-bit protected-mode boot code goes here.  We are still executing
	; the low-memory, identity-mapped copy of this code.
	;
	; edi -> linear address of PROCESSOR_START_BLOCK
	;

	;
	; Enable PAE mode (requisite for LongMode), load the tiled CR3
	;

	mov	eax, cr4
	or	eax, CR4_PAE
	mov	cr4, eax

	mov	eax, DWORD PTR [edi] + PsbTiledCr3
	mov	cr3, eax

	;
	; Set the long mode enable bit in the EFER msr
	;

	mov	ecx, MSR_EFER
	rdmsr
	or	eax, MSR_LMA
	wrmsr

	;
	; Enable paging and activate long mode
	;

	mov	eax, cr0
	or	eax, CR0_PG
	mov	cr0, eax

	;
	; Still in 32-bit legacy mode until we branch to a long mode
	; code selector
	;

	jmp	FAR PTR [edi] + PsbLmTarget

PMSTUB ENDS

	END