diff options
Diffstat (limited to 'OvmfPkg/ResetVector/Ia16/16RealTo32Flat.asm')
| -rw-r--r-- | OvmfPkg/ResetVector/Ia16/16RealTo32Flat.asm | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/OvmfPkg/ResetVector/Ia16/16RealTo32Flat.asm b/OvmfPkg/ResetVector/Ia16/16RealTo32Flat.asm new file mode 100644 index 0000000000..d030c0b52b --- /dev/null +++ b/OvmfPkg/ResetVector/Ia16/16RealTo32Flat.asm @@ -0,0 +1,151 @@ +;------------------------------------------------------------------------------
+;
+; Copyright (c) 2008, Intel Corporation
+; All rights reserved. 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.
+;
+; Module Name:
+;
+; 16RealTo32Flat.asm
+;
+; Abstract:
+;
+; Transition from 16 bit real mode into 32 bit flat protected mode
+;
+;------------------------------------------------------------------------------
+
+%define SEC_DEFAULT_CR0 0x40000023
+%define SEC_DEFAULT_CR4 0x640
+
+BITS 16
+
+to32BitFlat:
+
+ writeToSerialPort '1'
+ writeToSerialPort '6'
+ writeToSerialPort ' '
+
+ cli
+
+ mov bx, 0xf000
+ mov ds, bx
+
+ mov bx, ADDR16_OF(gdtr)
+
+o32 lgdt [bx]
+
+ mov eax, SEC_DEFAULT_CR0
+ mov cr0, eax
+
+; mov eax, cr0
+; or al, 1
+; mov cr0, eax
+
+ jmp LINEAR_CODE_SEL:dword ADDR_OF(jumpTo32BitAndLandHere)
+BITS 32
+jumpTo32BitAndLandHere:
+
+ mov eax, SEC_DEFAULT_CR4
+ mov cr4, eax
+
+ writeToSerialPort '3'
+ writeToSerialPort '2'
+ writeToSerialPort ' '
+
+ mov ax, LINEAR_SEL
+ mov ds, ax
+ mov es, ax
+ mov fs, ax
+ mov gs, ax
+ mov ss, ax
+
+ jmp TransitionFrom16RealTo32FlatComplete
+
+ALIGN 2
+
+gdtr:
+ dw GDT_END - GDT_BASE - 1 ; GDT limit
+ dd ADDR_OF(GDT_BASE)
+
+ALIGN 16
+
+GDT_BASE:
+; null descriptor
+NULL_SEL equ $-GDT_BASE
+ dw 0 ; limit 15:0
+ dw 0 ; base 15:0
+ db 0 ; base 23:16
+ db 0 ; type
+ db 0 ; limit 19:16, flags
+ db 0 ; base 31:24
+
+; linear data segment descriptor
+LINEAR_SEL equ $-GDT_BASE
+ dw 0FFFFh ; limit 0xFFFFF
+ dw 0 ; base 0
+ db 0
+ db 092h ; present, ring 0, data, expand-up, writable
+ db 0CFh ; page-granular, 32-bit
+ db 0
+
+; linear code segment descriptor
+LINEAR_CODE_SEL equ $-GDT_BASE
+ dw 0FFFFh ; limit 0xFFFFF
+ dw 0 ; base 0
+ db 0
+ db 09Ah ; present, ring 0, data, expand-up, writable
+ db 0CFh ; page-granular, 32-bit
+ db 0
+
+; system data segment descriptor
+SYS_DATA_SEL equ $-GDT_BASE
+ dw 0FFFFh ; limit 0xFFFFF
+ dw 0 ; base 0
+ db 0
+ db 092h ; present, ring 0, data, expand-up, writable
+ db 0CFh ; page-granular, 32-bit
+ db 0
+
+; system code segment descriptor
+SYS_CODE_SEL equ $-GDT_BASE
+ dw 0FFFFh ; limit 0xFFFFF
+ dw 0 ; base 0
+ db 0
+ db 09Ah ; present, ring 0, data, expand-up, writable
+ db 0CFh ; page-granular, 32-bit
+ db 0
+
+; spare segment descriptor
+LINEAR_CODE64_SEL equ $-GDT_BASE
+ DW -1 ; LimitLow
+ DW 0 ; BaseLow
+ DB 0 ; BaseMid
+ DB 9bh
+ DB 0afh ; LimitHigh (CS.L=1, CS.D=0)
+ DB 0 ; BaseHigh
+
+; spare segment descriptor
+SPARE4_SEL equ $-GDT_BASE
+ dw 0 ; limit 0xFFFFF
+ dw 0 ; base 0
+ db 0
+ db 0 ; present, ring 0, data, expand-up, writable
+ db 0 ; page-granular, 32-bit
+ db 0
+
+; spare segment descriptor
+SPARE5_SEL equ $-GDT_BASE
+ dw 0 ; limit 0xFFFFF
+ dw 0 ; base 0
+ db 0
+ db 0 ; present, ring 0, data, expand-up, writable
+ db 0 ; page-granular, 32-bit
+ db 0
+
+GDT_END:
+
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