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;; @file
; This is the code that goes from real-mode to protected mode.
; It consumes the reset vector, configures the stack.
;
; Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
; This program and the accompanying materials
; are licensed and made available under the terms and conditions of the BSD License
; which accompanies this distribution. The full text of the license may be found at
; http://opensource.org/licenses/bsd-license.php.
;
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
;;
;
; Define assembler characteristics
;
.586p
.xmm
.model flat, c
EXTRN TempRamInitApi:NEAR
.code
RET_ESI MACRO
movd esi, mm7 ; restore ESP from MM7
jmp esi
ENDM
;
; Perform early platform initialization
;
SecPlatformInit PROC NEAR PUBLIC
RET_ESI
SecPlatformInit ENDP
;
; Protected mode portion initializes stack, configures cache, and calls C entry point
;
;----------------------------------------------------------------------------
;
; Procedure: ProtectedModeEntryPoint
;
; Input: Executing in 32 Bit Protected (flat) mode
; cs: 0-4GB
; ds: 0-4GB
; es: 0-4GB
; fs: 0-4GB
; gs: 0-4GB
; ss: 0-4GB
;
; Output: This function never returns
;
; Destroys:
; ecx
; edi
; esi
; esp
;
; Description:
; Perform any essential early platform initilaisation
; Setup a stack
;
;----------------------------------------------------------------------------
ProtectedModeEntryPoint PROC NEAR C PUBLIC
;
; Dummy function. Consume 2 API to make sure they can be linked.
;
mov eax, TempRamInitApi
; Should never return
jmp $
ProtectedModeEntryPoint ENDP
;
; ROM-based Global-Descriptor Table for the PEI Phase
;
align 16
PUBLIC BootGdtTable
;
; GDT[0]: 0x00: Null entry, never used.
;
NULL_SEL equ $ - GDT_BASE ; Selector [0]
GDT_BASE:
BootGdtTable DD 0
DD 0
;
; Linear code segment descriptor
;
LINEAR_CODE_SEL equ $ - GDT_BASE ; Selector [0x8]
DW 0FFFFh ; limit 0xFFFF
DW 0 ; base 0
DB 0
DB 09Bh ; present, ring 0, data, expand-up, not-writable
DB 0CFh ; page-granular, 32-bit
DB 0
;
; System data segment descriptor
;
SYS_DATA_SEL equ $ - GDT_BASE ; Selector [0x10]
DW 0FFFFh ; limit 0xFFFF
DW 0 ; base 0
DB 0
DB 093h ; present, ring 0, data, expand-up, not-writable
DB 0CFh ; page-granular, 32-bit
DB 0
GDT_SIZE EQU $ - BootGDTtable ; Size, in bytes
;
; GDT Descriptor
;
GdtDesc: ; GDT descriptor
DW GDT_SIZE - 1 ; GDT limit
DD OFFSET BootGdtTable ; GDT base address
ProtectedModeEntryLinearAddress LABEL FWORD
ProtectedModeEntryLinearOffset LABEL DWORD
DD OFFSET ProtectedModeEntryPoint ; Offset of our 32 bit code
DW LINEAR_CODE_SEL
END
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