1 ;------------------------------------------------------------------------------ 2 ;* 3 ;* Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR> 4 ;* This program and the accompanying materials 5 ;* are licensed and made available under the terms and conditions of the BSD License 6 ;* which accompanies this distribution. The full text of the license may be found at 7 ;* http://opensource.org/licenses/bsd-license.php 8 ;* 9 ;* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 10 ;* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 11 ;* 12 ;* gpt.asm 13 ;* 14 ;* Abstract: 15 ;* 16 ;------------------------------------------------------------------------------ 17 18 .model small 19 ; .dosseg 20 .stack 21 .486p 22 .code 23 24 BLOCK_SIZE EQU 0200h 25 BLOCK_MASK EQU 01ffh 26 BLOCK_SHIFT EQU 9 27 28 ; **************************************************************************** 29 ; Code loaded by BIOS at 0x0000:0x7C00 30 ; **************************************************************************** 31 32 org 0h 33 Start: 34 35 ; **************************************************************************** 36 ; Start Print 37 ; **************************************************************************** 38 39 mov ax,0b800h 40 mov es,ax 41 mov ax, 07c0h 42 mov ds, ax 43 lea si, cs:[StartString] 44 mov cx, 10 45 mov di, 160 46 rep movsw 47 48 ; **************************************************************************** 49 ; Print over 50 ; **************************************************************************** 51 52 ; **************************************************************************** 53 ; Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600 54 ; **************************************************************************** 55 xor ax, ax ; AX = 0x0000 56 mov bx, 07c00h ; BX = 0x7C00 57 mov bp, 0600h ; BP = 0x0600 58 mov si, OFFSET RelocatedStart ; SI = Offset(RelocatedStart) 59 mov cx, 0200h ; CX = 0x0200 60 sub cx, si ; CS = 0x0200 - Offset(RelocatedStart) 61 lea di, [bp+si] ; DI = 0x0600 + Offset(RelocatedStart) 62 lea si, [bx+si] ; BX = 0x7C00 + Offset(RelocatedStart) 63 mov ss, ax ; SS = 0x0000 64 mov sp, bx ; SP = 0x7C00 65 mov es,ax ; ES = 0x0000 66 mov ds,ax ; DS = 0x0000 67 push ax ; PUSH 0x0000 68 push di ; PUSH 0x0600 + Offset(RelocatedStart) 69 cld ; Clear the direction flag 70 rep movsb ; Copy 0x0200 bytes from 0x7C00 to 0x0600 71 retf ; JMP 0x0000:0x0600 + Offset(RelocatedStart) 72 73 ; **************************************************************************** 74 ; Code relocated to 0x0000:0x0600 75 ; **************************************************************************** 76 77 RelocatedStart: 78 ; **************************************************************************** 79 ; Get Driver Parameters to 0x0000:0x7BFC 80 ; **************************************************************************** 81 xor ax,ax ; ax = 0 82 mov ss,ax ; ss = 0 83 add ax,1000h 84 mov ds,ax 85 86 mov sp,07c00h ; sp = 0x7c00 87 mov bp,sp ; bp = 0x7c00 88 89 mov ah,8 ; ah = 8 - Get Drive Parameters Function 90 mov byte ptr [bp+PhysicalDrive],dl ; BBS defines that BIOS would pass the booting driver number to the loader through DL 91 int 13h ; Get Drive Parameters 92 xor ax,ax ; ax = 0 93 mov al,dh ; al = dh 94 inc al ; MaxHead = al + 1 95 push ax ; 0000:7bfe = MaxHead 96 mov al,cl ; al = cl 97 and al,03fh ; MaxSector = al & 0x3f 98 push ax ; 0000:7bfc = MaxSector 99 100 ; **************************************************************************** 101 ; Read GPT Header from hard disk to 0x0000:0x0800 102 ; **************************************************************************** 103 xor ax, ax 104 mov es, ax ; Read to 0x0000:0x0800 105 mov di, 0800h ; Read to 0x0000:0x0800 106 mov eax, 1 ; Read LBA #1 107 mov edx, 0 ; Read LBA #1 108 mov bx, 1 ; Read 1 Block 109 push es 110 call ReadBlocks 111 pop es 112 113 ; **************************************************************************** 114 ; Read Target GPT Entry from hard disk to 0x0000:0x0A00 115 ; **************************************************************************** 116 cmp dword ptr es:[di], 020494645h ; Check for "EFI " 117 jne BadGpt 118 cmp dword ptr es:[di + 4], 054524150h ; Check for "PART" 119 jne BadGpt 120 cmp dword ptr es:[di + 8], 000010000h ; Check Revision - 0x10000 121 jne BadGpt 122 123 mov eax, dword ptr es:[di + 84] ; EAX = SizeOfPartitionEntry 124 mul byte ptr [bp+GptPartitionIndicator] ; EAX = SizeOfPartitionEntry * GptPartitionIndicator 125 mov edx, eax ; EDX = SizeOfPartitionEntry * GptPartitionIndicator 126 shr eax, BLOCK_SHIFT ; EAX = (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE 127 and edx, BLOCK_MASK ; EDX = Targer PartitionEntryLBA Offset 128 ; = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE 129 push edx 130 mov ecx, dword ptr es:[di + 72] ; ECX = PartitionEntryLBA (Low) 131 mov ebx, dword ptr es:[di + 76] ; EBX = PartitionEntryLBA (High) 132 add eax, ecx ; EAX = Target PartitionEntryLBA (Low) 133 ; = (PartitionEntryLBA + 134 ; (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE) 135 adc edx, ebx ; EDX = Target PartitionEntryLBA (High) 136 137 mov di, 0A00h ; Read to 0x0000:0x0A00 138 mov bx, 1 ; Read 1 Block 139 push es 140 call ReadBlocks 141 pop es 142 143 ; **************************************************************************** 144 ; Read Target DBR from hard disk to 0x0000:0x7C00 145 ; **************************************************************************** 146 pop edx ; EDX = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE 147 add di, dx ; DI = Targer PartitionEntryLBA Offset 148 cmp dword ptr es:[di], 0C12A7328h ; Check for EFI System Partition "C12A7328-F81F-11d2-BA4B-00A0C93EC93B" 149 jne BadGpt 150 cmp dword ptr es:[di + 4], 011d2F81Fh ; 151 jne BadGpt 152 cmp dword ptr es:[di + 8], 0A0004BBAh ; 153 jne BadGpt 154 cmp dword ptr es:[di + 0ch], 03BC93EC9h ; 155 jne BadGpt 156 157 mov eax, dword ptr es:[di + 32] ; EAX = StartingLBA (Low) 158 mov edx, dword ptr es:[di + 36] ; EDX = StartingLBA (High) 159 mov di, 07C00h ; Read to 0x0000:0x7C00 160 mov bx, 1 ; Read 1 Block 161 call ReadBlocks 162 163 ; **************************************************************************** 164 ; Transfer control to BootSector - Jump to 0x0000:0x7C00 165 ; **************************************************************************** 166 xor ax, ax 167 push ax ; PUSH 0x0000 168 mov di, 07c00h 169 push di ; PUSH 0x7C00 170 retf ; JMP 0x0000:0x7C00 171 172 ; **************************************************************************** 173 ; ReadBlocks - Reads a set of blocks from a block device 174 ; 175 ; EDX:EAX = Start LBA 176 ; BX = Number of Blocks to Read (must < 127) 177 ; ES:DI = Buffer to store sectors read from disk 178 ; **************************************************************************** 179 180 ; si = DiskAddressPacket 181 182 ReadBlocks: 183 pushad 184 push ds 185 xor cx, cx 186 mov ds, cx 187 mov bp, 0600h ; bp = 0x600 188 lea si, [bp + OFFSET AddressPacket] ; DS:SI = Disk Address Packet 189 mov BYTE PTR ds:[si+2],bl ; 02 = Number Of Block transfered 190 mov WORD PTR ds:[si+4],di ; 04 = Transfer Buffer Offset 191 mov WORD PTR ds:[si+6],es ; 06 = Transfer Buffer Segment 192 mov DWORD PTR ds:[si+8],eax ; 08 = Starting LBA (Low) 193 mov DWORD PTR ds:[si+0ch],edx ; 0C = Starting LBA (High) 194 mov ah, 42h ; ah = Function 42 195 mov dl,byte ptr [bp+PhysicalDrive] ; dl = Drive Number 196 int 13h 197 jc BadGpt 198 pop ds 199 popad 200 ret 201 202 ; **************************************************************************** 203 ; Address Packet used by ReadBlocks 204 ; **************************************************************************** 205 AddressPacket: 206 db 10h ; Size of address packet 207 db 00h ; Reserved. Must be 0 208 db 01h ; Read blocks at a time (To be fixed each times) 209 db 00h ; Reserved. Must be 0 210 dw 0000h ; Destination Address offset (To be fixed each times) 211 dw 0000h ; Destination Address segment (To be fixed each times) 212 AddressPacketLba: 213 dd 0h, 0h ; Start LBA (To be fixed each times) 214 AddressPacketEnd: 215 216 ; **************************************************************************** 217 ; ERROR Condition: 218 ; **************************************************************************** 219 220 BadGpt: 221 mov ax,0b800h 222 mov es,ax 223 mov ax, 060h 224 mov ds, ax 225 lea si, cs:[ErrorString] 226 mov cx, 10 227 mov di, 320 228 rep movsw 229 Halt: 230 jmp Halt 231 232 StartString: 233 db 'G', 0ch, 'P', 0ch, 'T', 0ch, ' ', 0ch, 'S', 0ch, 't', 0ch, 'a', 0ch, 'r', 0ch, 't', 0ch, '!', 0ch 234 ErrorString: 235 db 'G', 0ch, 'P', 0ch, 'T', 0ch, ' ', 0ch, 'E', 0ch, 'r', 0ch, 'r', 0ch, 'o', 0ch, 'r', 0ch, '!', 0ch 236 237 ; **************************************************************************** 238 ; PhysicalDrive - Used to indicate which disk to be boot 239 ; Can be patched by tool 240 ; **************************************************************************** 241 org 01B6h 242 PhysicalDrive db 80h 243 244 ; **************************************************************************** 245 ; GptPartitionIndicator - Used to indicate which GPT partition to be boot 246 ; Can be patched by tool 247 ; **************************************************************************** 248 org 01B7h 249 GptPartitionIndicator db 0 250 251 ; **************************************************************************** 252 ; Unique MBR signature 253 ; **************************************************************************** 254 org 01B8h 255 db 'DUET' 256 257 ; **************************************************************************** 258 ; Unknown 259 ; **************************************************************************** 260 org 01BCh 261 dw 0 262 263 ; **************************************************************************** 264 ; PMBR Entry - Can be patched by tool 265 ; **************************************************************************** 266 org 01BEh 267 db 0 ; Boot Indicator 268 db 0ffh ; Start Header 269 db 0ffh ; Start Sector 270 db 0ffh ; Start Track 271 db 0eeh ; OS Type 272 db 0ffh ; End Header 273 db 0ffh ; End Sector 274 db 0ffh ; End Track 275 dd 1 ; Starting LBA 276 dd 0FFFFFFFFh ; End LBA 277 278 org 01CEh 279 dd 0, 0, 0, 0 280 org 01DEh 281 dd 0, 0, 0, 0 282 org 01EEh 283 dd 0, 0, 0, 0 284 285 ; **************************************************************************** 286 ; Sector Signature 287 ; **************************************************************************** 288 289 org 01FEh 290 SectorSignature: 291 dw 0aa55h ; Boot Sector Signature 292 293 end 294 295
