OVMF Status Codes: Disable serial output, enable memory output

[mirror_edk2.git] / OvmfPkg / ResetVector / Ia16 / 16RealTo32Flat.asm

;------------------------------------------------------------------------------\r
; @file\r
; Transition from 16 bit real mode into 32 bit flat protected mode\r
;\r
; Copyright (c) 2008 - 2009, Intel Corporation\r
; All rights reserved. This program and the accompanying materials\r
; are licensed and made available under the terms and conditions of the BSD License\r
; which accompanies this distribution.  The full text of the license may be found at\r
; http://opensource.org/licenses/bsd-license.php\r
;\r
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
;\r
;------------------------------------------------------------------------------\r
\r
%define SEC_DEFAULT_CR0  0x40000023\r
%define SEC_DEFAULT_CR4  0x640\r
\r
BITS    16\r
\r
;\r
; Modified:  EAX, EBX\r
;\r
TransitionFromReal16To32BitFlat:\r
\r
    debugShowPostCode POSTCODE_16BIT_MODE\r
\r
    cli\r
\r
    mov     bx, 0xf000\r
    mov     ds, bx\r
\r
    mov     bx, ADDR16_OF(gdtr)\r
\r
o32 lgdt    [bx]\r
\r
    mov     eax, SEC_DEFAULT_CR0\r
    mov     cr0, eax\r
\r
    jmp     LINEAR_CODE_SEL:dword ADDR_OF(jumpTo32BitAndLandHere)\r
BITS    32\r
jumpTo32BitAndLandHere:\r
\r
    mov     eax, SEC_DEFAULT_CR4\r
    mov     cr4, eax\r
\r
    debugShowPostCode POSTCODE_32BIT_MODE\r
\r
    mov     ax, LINEAR_SEL\r
    mov     ds, ax\r
    mov     es, ax\r
    mov     fs, ax\r
    mov     gs, ax\r
    mov     ss, ax\r
\r
    OneTimeCallRet TransitionFromReal16To32BitFlat\r
\r
ALIGN   2\r
\r
gdtr:\r
    dw      GDT_END - GDT_BASE - 1   ; GDT limit\r
    dd      ADDR_OF(GDT_BASE)\r
\r
ALIGN   16\r
\r
GDT_BASE:\r
; null descriptor\r
NULL_SEL            equ $-GDT_BASE\r
    dw      0            ; limit 15:0\r
    dw      0            ; base 15:0\r
    db      0            ; base 23:16\r
    db      0            ; type\r
    db      0            ; limit 19:16, flags\r
    db      0            ; base 31:24\r
\r
; linear data segment descriptor\r
LINEAR_SEL      equ $-GDT_BASE\r
    dw      0FFFFh       ; limit 0xFFFFF\r
    dw      0            ; base 0\r
    db      0\r
    db      092h         ; present, ring 0, data, expand-up, writable\r
    db      0CFh         ; page-granular, 32-bit\r
    db      0\r
\r
; linear code segment descriptor\r
LINEAR_CODE_SEL equ $-GDT_BASE\r
    dw      0FFFFh       ; limit 0xFFFFF\r
    dw      0            ; base 0\r
    db      0\r
    db      09Ah         ; present, ring 0, data, expand-up, writable\r
    db      0CFh         ; page-granular, 32-bit\r
    db      0\r
\r
; system data segment descriptor\r
SYS_DATA_SEL    equ $-GDT_BASE\r
    dw      0FFFFh       ; limit 0xFFFFF\r
    dw      0            ; base 0\r
    db      0\r
    db      092h         ; present, ring 0, data, expand-up, writable\r
    db      0CFh         ; page-granular, 32-bit\r
    db      0\r
\r
; system code segment descriptor\r
SYS_CODE_SEL    equ $-GDT_BASE\r
    dw      0FFFFh       ; limit 0xFFFFF\r
    dw      0            ; base 0\r
    db      0\r
    db      09Ah         ; present, ring 0, data, expand-up, writable\r
    db      0CFh         ; page-granular, 32-bit\r
    db      0\r
\r
; spare segment descriptor\r
LINEAR_CODE64_SEL  equ $-GDT_BASE\r
    DW      -1           ; LimitLow\r
    DW      0            ; BaseLow\r
    DB      0            ; BaseMid\r
    DB      9bh\r
    DB      0afh         ; LimitHigh   (CS.L=1, CS.D=0)\r
    DB      0            ; BaseHigh\r
\r
; spare segment descriptor\r
SPARE4_SEL  equ $-GDT_BASE\r
    dw      0            ; limit 0xFFFFF\r
    dw      0            ; base 0\r
    db      0\r
    db      0            ; present, ring 0, data, expand-up, writable\r
    db      0            ; page-granular, 32-bit\r
    db      0\r
\r
; spare segment descriptor\r
SPARE5_SEL  equ $-GDT_BASE\r
    dw      0            ; limit 0xFFFFF\r
    dw      0            ; base 0\r
    db      0\r
    db      0            ; present, ring 0, data, expand-up, writable\r
    db      0            ; page-granular, 32-bit\r
    db      0\r
\r
GDT_END:\r
\r