[mirror_edk2.git] / DuetPkg / BootSector / Gpt.asm

;------------------------------------------------------------------------------\r
;*\r
;*   Copyright 2006 - 2007, 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
;*    gpt.asm\r
;*  \r
;*   Abstract:\r
;*\r
;------------------------------------------------------------------------------\r
\r
    .model  small\r
;   .dosseg\r
    .stack\r
    .486p\r
    .code\r
\r
BLOCK_SIZE                EQU     0200h\r
BLOCK_MASK                EQU     01ffh\r
BLOCK_SHIFT               EQU     9\r
\r
; ****************************************************************************\r
; Code loaded by BIOS at 0x0000:0x7C00\r
; ****************************************************************************\r
\r
        org 0h\r
Start:\r
\r
; ****************************************************************************\r
; Start Print\r
; ****************************************************************************\r
\r
    mov  ax,0b800h\r
    mov  es,ax\r
    mov  ax, 07c0h\r
    mov  ds, ax\r
    lea  si, cs:[StartString]\r
    mov  cx, 10\r
    mov  di, 160\r
    rep  movsw \r
\r
; ****************************************************************************\r
; Print over\r
; ****************************************************************************\r
\r
; ****************************************************************************\r
; Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600\r
; ****************************************************************************\r
        xor   ax, ax                    ; AX = 0x0000  \r
        mov   bx, 07c00h                ; BX = 0x7C00\r
        mov   bp, 0600h                 ; BP = 0x0600\r
        mov   si, OFFSET RelocatedStart ; SI = Offset(RelocatedStart)\r
        mov   cx, 0200h                 ; CX = 0x0200\r
        sub   cx, si                    ; CS = 0x0200 - Offset(RelocatedStart)\r
        lea   di, [bp+si]               ; DI = 0x0600 + Offset(RelocatedStart)\r
        lea   si, [bx+si]               ; BX = 0x7C00 + Offset(RelocatedStart)\r
        mov   ss, ax                    ; SS = 0x0000\r
        mov   sp, bx                    ; SP = 0x7C00\r
        mov   es,ax                     ; ES = 0x0000\r
        mov   ds,ax                     ; DS = 0x0000\r
        push  ax                        ; PUSH 0x0000\r
        push  di                        ; PUSH 0x0600 + Offset(RelocatedStart)\r
        cld                             ; Clear the direction flag\r
        rep   movsb                     ; Copy 0x0200 bytes from 0x7C00 to 0x0600\r
        retf                            ; JMP 0x0000:0x0600 + Offset(RelocatedStart)\r
\r
; ****************************************************************************\r
; Code relocated to 0x0000:0x0600\r
; ****************************************************************************\r
\r
RelocatedStart:\r
; ****************************************************************************\r
; Get Driver Parameters to 0x0000:0x7BFC\r
; ****************************************************************************\r
        xor   ax,ax         ; ax = 0\r
        mov   ss,ax         ; ss = 0\r
        add   ax,1000h\r
        mov   ds,ax\r
\r
        mov   sp,07c00h     ; sp = 0x7c00\r
        mov   bp,sp         ; bp = 0x7c00\r
\r
        mov   ah,8                                ; ah = 8 - Get Drive Parameters Function\r
        mov   byte ptr [bp+PhysicalDrive],dl      ; BBS defines that BIOS would pass the booting driver number to the loader through DL\r
        int   13h                                 ; Get Drive Parameters\r
        xor   ax,ax                   ; ax = 0\r
        mov   al,dh                   ; al = dh\r
        inc   al                      ; MaxHead = al + 1\r
        push  ax                      ; 0000:7bfe = MaxHead\r
        mov   al,cl                   ; al = cl\r
        and   al,03fh                 ; MaxSector = al & 0x3f\r
        push  ax                      ; 0000:7bfc = MaxSector\r
\r
; ****************************************************************************\r
; Read GPT Header from hard disk to 0x0000:0x0800\r
; ****************************************************************************\r
        xor     ax, ax\r
        mov     es, ax                            ; Read to 0x0000:0x0800\r
        mov     di, 0800h                         ; Read to 0x0000:0x0800\r
        mov     eax, 1                            ; Read LBA #1\r
        mov     edx, 0                            ; Read LBA #1\r
        mov     bx, 1                             ; Read 1 Block\r
        push    es\r
        call    ReadBlocks\r
        pop     es\r
\r
; ****************************************************************************\r
; Read Target GPT Entry from hard disk to 0x0000:0x0A00\r
; ****************************************************************************\r
        cmp   dword ptr es:[di], 020494645h       ; Check for "EFI "\r
        jne   BadGpt\r
        cmp   dword ptr es:[di + 4], 054524150h   ; Check for "PART"\r
        jne   BadGpt\r
        cmp   dword ptr es:[di + 8], 000010000h   ; Check Revision - 0x10000\r
        jne   BadGpt\r
\r
        mov   eax, dword ptr es:[di + 84]         ; EAX = SizeOfPartitionEntry\r
        mul   byte ptr [bp+GptPartitionIndicator] ; EAX = SizeOfPartitionEntry * GptPartitionIndicator\r
        mov   edx, eax                            ; EDX = SizeOfPartitionEntry * GptPartitionIndicator\r
        shr   eax, BLOCK_SHIFT                    ; EAX = (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE\r
        and   edx, BLOCK_MASK                     ; EDX = Targer PartitionEntryLBA Offset\r
                                                  ;     = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE\r
        push  edx\r
        mov   ecx, dword ptr es:[di + 72]         ; ECX = PartitionEntryLBA (Low)\r
        mov   ebx, dword ptr es:[di + 76]         ; EBX = PartitionEntryLBA (High)\r
        add   eax, ecx                            ; EAX = Target PartitionEntryLBA (Low)\r
                                                  ;     = (PartitionEntryLBA + \r
                                                  ;        (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE)\r
        adc   edx, ebx                            ; EDX = Target PartitionEntryLBA (High)\r
\r
        mov   di, 0A00h                           ; Read to 0x0000:0x0A00\r
        mov   bx, 1                               ; Read 1 Block\r
        push  es\r
        call  ReadBlocks\r
        pop   es\r
\r
; ****************************************************************************\r
; Read Target DBR from hard disk to 0x0000:0x7C00\r
; ****************************************************************************\r
        pop   edx                                 ; EDX = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE\r
        add   di, dx                              ; DI = Targer PartitionEntryLBA Offset\r
        cmp   dword ptr es:[di], 0C12A7328h       ; Check for EFI System Partition "C12A7328-F81F-11d2-BA4B-00A0C93EC93B"\r
        jne   BadGpt\r
        cmp   dword ptr es:[di + 4], 011d2F81Fh   ; \r
        jne   BadGpt\r
        cmp   dword ptr es:[di + 8], 0A0004BBAh   ; \r
        jne   BadGpt\r
        cmp   dword ptr es:[di + 0ch], 03BC93EC9h ; \r
        jne   BadGpt\r
\r
        mov   eax, dword ptr es:[di + 32]         ; EAX = StartingLBA (Low)\r
        mov   edx, dword ptr es:[di + 36]         ; EDX = StartingLBA (High)\r
        mov   di, 07C00h                          ; Read to 0x0000:0x7C00\r
        mov   bx, 1                               ; Read 1 Block\r
        call  ReadBlocks\r
\r
; ****************************************************************************\r
; Transfer control to BootSector - Jump to 0x0000:0x7C00\r
; ****************************************************************************\r
        xor   ax, ax\r
        push  ax                        ; PUSH 0x0000\r
        mov   di, 07c00h\r
        push  di                        ; PUSH 0x7C00\r
        retf                            ; JMP 0x0000:0x7C00\r
\r
; ****************************************************************************\r
; ReadBlocks - Reads a set of blocks from a block device\r
;\r
; EDX:EAX = Start LBA\r
; BX      = Number of Blocks to Read (must < 127)\r
; ES:DI   = Buffer to store sectors read from disk\r
; ****************************************************************************\r
\r
; si = DiskAddressPacket\r
\r
ReadBlocks:\r
        pushad\r
        push  ds\r
        xor   cx, cx\r
        mov   ds, cx\r
        mov   bp, 0600h                         ; bp = 0x600\r
        lea   si, [bp + OFFSET AddressPacket]   ; DS:SI = Disk Address Packet\r
        mov   BYTE PTR ds:[si+2],bl             ;    02 = Number Of Block transfered\r
        mov   WORD PTR ds:[si+4],di             ;    04 = Transfer Buffer Offset\r
        mov   WORD PTR ds:[si+6],es             ;    06 = Transfer Buffer Segment\r
        mov   DWORD PTR ds:[si+8],eax           ;    08 = Starting LBA (Low)\r
        mov   DWORD PTR ds:[si+0ch],edx         ;    0C = Starting LBA (High)\r
        mov   ah, 42h                           ; ah = Function 42\r
        mov   dl,byte ptr [bp+PhysicalDrive]    ; dl = Drive Number\r
        int   13h\r
        jc    BadGpt\r
        pop   ds\r
        popad\r
        ret\r
\r
; ****************************************************************************\r
; Address Packet used by ReadBlocks\r
; ****************************************************************************\r
AddressPacket:\r
        db    10h                       ; Size of address packet\r
        db    00h                       ; Reserved.  Must be 0\r
        db    01h                       ; Read blocks at a time (To be fixed each times)\r
        db    00h                       ; Reserved.  Must be 0\r
        dw    0000h                     ; Destination Address offset (To be fixed each times)\r
        dw    0000h                     ; Destination Address segment (To be fixed each times)\r
AddressPacketLba:\r
        dd    0h, 0h                    ; Start LBA (To be fixed each times)\r
AddressPacketEnd:\r
\r
; ****************************************************************************\r
; ERROR Condition:\r
; ****************************************************************************\r
\r
BadGpt:\r
    mov  ax,0b800h\r
    mov  es,ax\r
    mov  ax, 060h\r
    mov  ds, ax\r
    lea  si, cs:[ErrorString]\r
    mov  cx, 10\r
    mov  di, 320\r
    rep  movsw \r
Halt:\r
    jmp   Halt\r
\r
StartString:\r
    db 'G', 0ch, 'P', 0ch, 'T', 0ch, ' ', 0ch, 'S', 0ch, 't', 0ch, 'a', 0ch, 'r', 0ch, 't', 0ch, '!', 0ch\r
ErrorString:\r
    db 'G', 0ch, 'P', 0ch, 'T', 0ch, ' ', 0ch, 'E', 0ch, 'r', 0ch, 'r', 0ch, 'o', 0ch, 'r', 0ch, '!', 0ch\r
\r
; ****************************************************************************\r
; PhysicalDrive - Used to indicate which disk to be boot\r
;                 Can be patched by tool\r
; ****************************************************************************\r
    org   01B6h\r
PhysicalDrive         db  80h\r
\r
; ****************************************************************************\r
; GptPartitionIndicator - Used to indicate which GPT partition to be boot\r
;                         Can be patched by tool\r
; ****************************************************************************\r
    org   01B7h\r
GptPartitionIndicator db 0\r
\r
; ****************************************************************************\r
; Unique MBR signature\r
; ****************************************************************************\r
    org   01B8h\r
    db 'DUET'\r
\r
; ****************************************************************************\r
; Unknown\r
; ****************************************************************************\r
    org   01BCh\r
    dw 0\r
\r
; ****************************************************************************\r
; PMBR Entry - Can be patched by tool\r
; ****************************************************************************\r
    org   01BEh\r
    db 0          ; Boot Indicator\r
    db 0ffh       ; Start Header\r
    db 0ffh       ; Start Sector\r
    db 0ffh       ; Start Track\r
    db 0eeh       ; OS Type\r
    db 0ffh       ; End Header\r
    db 0ffh       ; End Sector\r
    db 0ffh       ; End Track\r
    dd 1          ; Starting LBA\r
    dd 0FFFFFFFFh ; End LBA\r
\r
    org   01CEh\r
    dd 0, 0, 0, 0\r
    org   01DEh\r
    dd 0, 0, 0, 0\r
    org   01EEh\r
    dd 0, 0, 0, 0\r
\r
; ****************************************************************************\r
; Sector Signature\r
; ****************************************************************************\r
\r
  org 01FEh\r
SectorSignature:\r
  dw        0aa55h      ; Boot Sector Signature\r
\r
  end \r
  \r
Commit	Line	Data
c69dd9df	1	;------------------------------------------------------------------------------\r
	2	;*\r
	3	;* Copyright 2006 - 2007, Intel Corporation \r
	4	;* All rights reserved. This program and the accompanying materials \r
	5	;* are licensed and made available under the terms and conditions of the BSD License \r
	6	;* which accompanies this distribution. The full text of the license may be found at \r
	7	;* http://opensource.org/licenses/bsd-license.php \r
	8	;* \r
	9	;* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r
	10	;* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r
	11	;* \r
	12	;* gpt.asm\r
	13	;* \r
	14	;* Abstract:\r
	15	;*\r
	16	;------------------------------------------------------------------------------\r
	17	\r
	18	.model small\r
	19	; .dosseg\r
	20	.stack\r
	21	.486p\r
	22	.code\r
	23	\r
	24	BLOCK_SIZE EQU 0200h\r
	25	BLOCK_MASK EQU 01ffh\r
	26	BLOCK_SHIFT EQU 9\r
	27	\r
	28	; ****************************************************************************\r
	29	; Code loaded by BIOS at 0x0000:0x7C00\r
	30	; ****************************************************************************\r
	31	\r
	32	org 0h\r
	33	Start:\r
	34	\r
	35	; ****************************************************************************\r
	36	; Start Print\r
	37	; ****************************************************************************\r
	38	\r
	39	mov ax,0b800h\r
	40	mov es,ax\r
	41	mov ax, 07c0h\r
	42	mov ds, ax\r
	43	lea si, cs:[StartString]\r
	44	mov cx, 10\r
	45	mov di, 160\r
	46	rep movsw \r
	47	\r
	48	; ****************************************************************************\r
	49	; Print over\r
	50	; ****************************************************************************\r
	51	\r
	52	; ****************************************************************************\r
	53	; Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600\r
	54	; ****************************************************************************\r
	55	xor ax, ax ; AX = 0x0000 \r
	56	mov bx, 07c00h ; BX = 0x7C00\r
	57	mov bp, 0600h ; BP = 0x0600\r
	58	mov si, OFFSET RelocatedStart ; SI = Offset(RelocatedStart)\r
	59	mov cx, 0200h ; CX = 0x0200\r
	60	sub cx, si ; CS = 0x0200 - Offset(RelocatedStart)\r
	61	lea di, [bp+si] ; DI = 0x0600 + Offset(RelocatedStart)\r
	62	lea si, [bx+si] ; BX = 0x7C00 + Offset(RelocatedStart)\r
	63	mov ss, ax ; SS = 0x0000\r
	64	mov sp, bx ; SP = 0x7C00\r
65	mov es,ax ; ES = 0x0000\r
66	mov ds,ax ; DS = 0x0000\r
67	push ax ; PUSH 0x0000\r
68	push di ; PUSH 0x0600 + Offset(RelocatedStart)\r
69	cld ; Clear the direction flag\r
70	rep movsb ; Copy 0x0200 bytes from 0x7C00 to 0x0600\r
71	retf ; JMP 0x0000:0x0600 + Offset(RelocatedStart)\r
72	\r
73	; ****************************************************************************\r
74	; Code relocated to 0x0000:0x0600\r
75	; ****************************************************************************\r
76	\r
77	RelocatedStart:\r
78	; ****************************************************************************\r
79	; Get Driver Parameters to 0x0000:0x7BFC\r
80	; ****************************************************************************\r
81	xor ax,ax ; ax = 0\r
82	mov ss,ax ; ss = 0\r
83	add ax,1000h\r
84	mov ds,ax\r
85	\r
86	mov sp,07c00h ; sp = 0x7c00\r
87	mov bp,sp ; bp = 0x7c00\r
88	\r
89	mov ah,8 ; ah = 8 - Get Drive Parameters Function\r
90	mov byte ptr [bp+PhysicalDrive],dl ; BBS defines that BIOS would pass the booting driver number to the loader through DL\r
91	int 13h ; Get Drive Parameters\r
92	xor ax,ax ; ax = 0\r
93	mov al,dh ; al = dh\r
94	inc al ; MaxHead = al + 1\r
95	push ax ; 0000:7bfe = MaxHead\r
96	mov al,cl ; al = cl\r
97	and al,03fh ; MaxSector = al & 0x3f\r
98	push ax ; 0000:7bfc = MaxSector\r
99	\r
100	; ****************************************************************************\r
101	; Read GPT Header from hard disk to 0x0000:0x0800\r
102	; ****************************************************************************\r
103	xor ax, ax\r
104	mov es, ax ; Read to 0x0000:0x0800\r
105	mov di, 0800h ; Read to 0x0000:0x0800\r
106	mov eax, 1 ; Read LBA #1\r
107	mov edx, 0 ; Read LBA #1\r
108	mov bx, 1 ; Read 1 Block\r
109	push es\r
110	call ReadBlocks\r
111	pop es\r
112	\r
113	; ****************************************************************************\r
114	; Read Target GPT Entry from hard disk to 0x0000:0x0A00\r
115	; ****************************************************************************\r
116	cmp dword ptr es:[di], 020494645h ; Check for "EFI "\r
117	jne BadGpt\r
118	cmp dword ptr es:[di + 4], 054524150h ; Check for "PART"\r
119	jne BadGpt\r
120	cmp dword ptr es:[di + 8], 000010000h ; Check Revision - 0x10000\r
121	jne BadGpt\r
122	\r
123	mov eax, dword ptr es:[di + 84] ; EAX = SizeOfPartitionEntry\r
124	mul byte ptr [bp+GptPartitionIndicator] ; EAX = SizeOfPartitionEntry * GptPartitionIndicator\r
125	mov edx, eax ; EDX = SizeOfPartitionEntry * GptPartitionIndicator\r
126	shr eax, BLOCK_SHIFT ; EAX = (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE\r
127	and edx, BLOCK_MASK ; EDX = Targer PartitionEntryLBA Offset\r
128	; = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE\r
129	push edx\r
130	mov ecx, dword ptr es:[di + 72] ; ECX = PartitionEntryLBA (Low)\r
131	mov ebx, dword ptr es:[di + 76] ; EBX = PartitionEntryLBA (High)\r
132	add eax, ecx ; EAX = Target PartitionEntryLBA (Low)\r
133	; = (PartitionEntryLBA + \r
134	; (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE)\r
135	adc edx, ebx ; EDX = Target PartitionEntryLBA (High)\r
136	\r
137	mov di, 0A00h ; Read to 0x0000:0x0A00\r
138	mov bx, 1 ; Read 1 Block\r
139	push es\r
140	call ReadBlocks\r
141	pop es\r
142	\r
143	; ****************************************************************************\r
144	; Read Target DBR from hard disk to 0x0000:0x7C00\r
145	; ****************************************************************************\r
146	pop edx ; EDX = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE\r
147	add di, dx ; DI = Targer PartitionEntryLBA Offset\r
148	cmp dword ptr es:[di], 0C12A7328h ; Check for EFI System Partition "C12A7328-F81F-11d2-BA4B-00A0C93EC93B"\r
149	jne BadGpt\r
150	cmp dword ptr es:[di + 4], 011d2F81Fh ; \r
151	jne BadGpt\r
152	cmp dword ptr es:[di + 8], 0A0004BBAh ; \r
153	jne BadGpt\r
154	cmp dword ptr es:[di + 0ch], 03BC93EC9h ; \r
155	jne BadGpt\r
156	\r
157	mov eax, dword ptr es:[di + 32] ; EAX = StartingLBA (Low)\r
158	mov edx, dword ptr es:[di + 36] ; EDX = StartingLBA (High)\r
159	mov di, 07C00h ; Read to 0x0000:0x7C00\r
160	mov bx, 1 ; Read 1 Block\r
161	call ReadBlocks\r
162	\r
163	; ****************************************************************************\r
164	; Transfer control to BootSector - Jump to 0x0000:0x7C00\r
165	; ****************************************************************************\r
166	xor ax, ax\r
167	push ax ; PUSH 0x0000\r
168	mov di, 07c00h\r
169	push di ; PUSH 0x7C00\r
170	retf ; JMP 0x0000:0x7C00\r
171	\r
172	; ****************************************************************************\r
173	; ReadBlocks - Reads a set of blocks from a block device\r
174	;\r
175	; EDX:EAX = Start LBA\r
176	; BX = Number of Blocks to Read (must < 127)\r
177	; ES:DI = Buffer to store sectors read from disk\r
178	; ****************************************************************************\r
179	\r
180	; si = DiskAddressPacket\r
181	\r
182	ReadBlocks:\r
183	pushad\r
184	push ds\r
185	xor cx, cx\r
186	mov ds, cx\r
187	mov bp, 0600h ; bp = 0x600\r
188	lea si, [bp + OFFSET AddressPacket] ; DS:SI = Disk Address Packet\r
189	mov BYTE PTR ds:[si+2],bl ; 02 = Number Of Block transfered\r
190	mov WORD PTR ds:[si+4],di ; 04 = Transfer Buffer Offset\r
191	mov WORD PTR ds:[si+6],es ; 06 = Transfer Buffer Segment\r
192	mov DWORD PTR ds:[si+8],eax ; 08 = Starting LBA (Low)\r
193	mov DWORD PTR ds:[si+0ch],edx ; 0C = Starting LBA (High)\r
194	mov ah, 42h ; ah = Function 42\r
195	mov dl,byte ptr [bp+PhysicalDrive] ; dl = Drive Number\r
196	int 13h\r
197	jc BadGpt\r
198	pop ds\r
199	popad\r
200	ret\r
201	\r
202	; ****************************************************************************\r
203	; Address Packet used by ReadBlocks\r
204	; ****************************************************************************\r
205	AddressPacket:\r
206	db 10h ; Size of address packet\r
207	db 00h ; Reserved. Must be 0\r
208	db 01h ; Read blocks at a time (To be fixed each times)\r
209	db 00h ; Reserved. Must be 0\r
210	dw 0000h ; Destination Address offset (To be fixed each times)\r
211	dw 0000h ; Destination Address segment (To be fixed each times)\r
212	AddressPacketLba:\r
213	dd 0h, 0h ; Start LBA (To be fixed each times)\r
214	AddressPacketEnd:\r
215	\r
216	; ****************************************************************************\r
217	; ERROR Condition:\r
218	; ****************************************************************************\r
219	\r
220	BadGpt:\r
221	mov ax,0b800h\r
222	mov es,ax\r
223	mov ax, 060h\r
224	mov ds, ax\r
225	lea si, cs:[ErrorString]\r
226	mov cx, 10\r
227	mov di, 320\r
228	rep movsw \r
229	Halt:\r
230	jmp Halt\r
231	\r
232	StartString:\r
233	db 'G', 0ch, 'P', 0ch, 'T', 0ch, ' ', 0ch, 'S', 0ch, 't', 0ch, 'a', 0ch, 'r', 0ch, 't', 0ch, '!', 0ch\r
234	ErrorString:\r
235	db 'G', 0ch, 'P', 0ch, 'T', 0ch, ' ', 0ch, 'E', 0ch, 'r', 0ch, 'r', 0ch, 'o', 0ch, 'r', 0ch, '!', 0ch\r
236	\r
237	; ****************************************************************************\r
238	; PhysicalDrive - Used to indicate which disk to be boot\r
239	; Can be patched by tool\r
240	; ****************************************************************************\r
241	org 01B6h\r
242	PhysicalDrive db 80h\r
243	\r
244	; ****************************************************************************\r
245	; GptPartitionIndicator - Used to indicate which GPT partition to be boot\r
246	; Can be patched by tool\r
247	; ****************************************************************************\r
248	org 01B7h\r
249	GptPartitionIndicator db 0\r
250	\r
251	; ****************************************************************************\r
252	; Unique MBR signature\r
253	; ****************************************************************************\r
254	org 01B8h\r
255	db 'DUET'\r
256	\r
257	; ****************************************************************************\r
258	; Unknown\r
259	; ****************************************************************************\r
260	org 01BCh\r
261	dw 0\r
262	\r
263	; ****************************************************************************\r
264	; PMBR Entry - Can be patched by tool\r
265	; ****************************************************************************\r
266	org 01BEh\r
267	db 0 ; Boot Indicator\r
268	db 0ffh ; Start Header\r
269	db 0ffh ; Start Sector\r
270	db 0ffh ; Start Track\r
271	db 0eeh ; OS Type\r
272	db 0ffh ; End Header\r
273	db 0ffh ; End Sector\r
274	db 0ffh ; End Track\r
275	dd 1 ; Starting LBA\r
276	dd 0FFFFFFFFh ; End LBA\r
277	\r
278	org 01CEh\r
279	dd 0, 0, 0, 0\r
280	org 01DEh\r
281	dd 0, 0, 0, 0\r
282	org 01EEh\r
283	dd 0, 0, 0, 0\r
284	\r
285	; ****************************************************************************\r
286	; Sector Signature\r
287	; ****************************************************************************\r
288	\r
289	org 01FEh\r
290	SectorSignature:\r
291	dw 0aa55h ; Boot Sector Signature\r
292	\r
293	end \r
294	\r