1 #------------------------------------------------------------------------------ 2 #* 3 #* Copyright (c) 2006 - 2011, 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 .code16 23 24 .equ BLOCK_SIZE, 0x0200 25 .equ BLOCK_MASK, 0x01ff 26 .equ BLOCK_SHIFT, 9 27 28 # **************************************************************************** 29 # Code loaded by BIOS at 0x0000:0x7C00 30 # **************************************************************************** 31 32 .org 0x00 33 Start: 34 35 # **************************************************************************** 36 # Start Print 37 # **************************************************************************** 38 39 movw $0xb800, %ax 40 movw %ax, %es 41 movw $0x7c0, %ax 42 movw %ax, %ds 43 leaw %cs:StartString, %si 44 movw $10, %cx 45 movw $160, %di 46 rep 47 movsw 48 49 # **************************************************************************** 50 # Print over 51 # **************************************************************************** 52 53 # **************************************************************************** 54 # Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600 55 # **************************************************************************** 56 xorw %ax, %ax # AX = 0x0000 57 movw $0x7c00, %bx # BX = 0x7C00 58 movw $0x600, %bp # BP = 0x0600 59 movw RelocatedStart, %si # SI = Offset(RelocatedStart) 60 movw $0x200, %cx # CX = 0x0200 61 subw %si, %cx # CS = 0x0200 - Offset(RelocatedStart) 62 leaw (%bp,%si,), %di # DI = 0x0600 + Offset(RelocatedStart) 63 leaw (%bx,%si,), %si # BX = 0x7C00 + Offset(RelocatedStart) 64 movw %ax, %ss # SS = 0x0000 65 movw %bx, %sp # SP = 0x7C00 66 movw %ax, %es # ES = 0x0000 67 movw %ax, %ds # DS = 0x0000 68 pushw %ax # PUSH 0x0000 69 pushw %di # PUSH 0x0600 + Offset(RelocatedStart) 70 cld # Clear the direction flag 71 rep 72 movsb # Copy 0x0200 bytes from 0x7C00 to 0x0600 73 retl # JMP 0x0000:0x0600 + Offset(RelocatedStart) 74 75 # **************************************************************************** 76 # Code relocated to 0x0000:0x0600 77 # **************************************************************************** 78 79 RelocatedStart: 80 # **************************************************************************** 81 # Get Driver Parameters to 0x0000:0x7BFC 82 # **************************************************************************** 83 xorw %ax, %ax # ax = 0 84 movw %ax, %ss # ss = 0 85 addw $0x1000, %ax 86 movw %ax, %ds 87 88 movw $0x7c00, %sp # sp = 0x7c00 89 movw %sp, %bp # bp = 0x7c00 90 91 movb $8, %ah # ah = 8 - Get Drive Parameters Function 92 movb %dl, PhysicalDrive(%bp) # BBS defines that BIOS would pass the booting driver number to the loader through DL 93 int $0x13 # Get Drive Parameters 94 xorw %ax, %ax # ax = 0 95 movb %dh, %al # al = dh 96 incb %al # MaxHead = al + 1 97 pushw %ax # 0000:7bfe = MaxHead 98 movb %cl, %al # al = cl 99 andb $0x3f, %al # MaxSector = al & 0x3f 100 pushw %ax # 0000:7bfc = MaxSector 101 102 # **************************************************************************** 103 # Read GPT Header from hard disk to 0x0000:0x0800 104 # **************************************************************************** 105 xorw %ax, %ax 106 movw %ax, %es # Read to 0x0000:0x0800 107 movw $0x800, %di # Read to 0x0000:0x0800 108 movl $1, %eax # Read LBA #1 109 movl $0, %edx # Read LBA #1 110 movw $1, %bx # Read 1 Block 111 pushw %es 112 call ReadBlocks 113 popw %es 114 115 # **************************************************************************** 116 # Read Target GPT Entry from hard disk to 0x0000:0x0A00 117 # **************************************************************************** 118 cmpl $0x20494645, %es:(%di) # Check for "EFI " 119 jne BadGpt 120 cmpl $0x54524150, %es:4(%di) # Check for "PART" 121 jne BadGpt 122 cmpl $0x00010000, %es:8(%di) # Check Revision - 0x10000 123 jne BadGpt 124 125 movl %es:84(%di), %eax # EAX = SizeOfPartitionEntry 126 mulb GptPartitionIndicator(%bp) # EAX = SizeOfPartitionEntry * GptPartitionIndicator 127 movl %eax, %edx # EDX = SizeOfPartitionEntry * GptPartitionIndicator 128 shrl $BLOCK_SHIFT, %eax # EAX = (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE 129 andl $BLOCK_MASK, %edx # EDX = Targer PartitionEntryLBA Offset 130 # = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE 131 pushl %edx 132 movl %es:72(%di), %ecx # ECX = PartitionEntryLBA (Low) 133 movl %es:76(%di), %ebx # EBX = PartitionEntryLBA (High) 134 addl %ecx, %eax # EAX = Target PartitionEntryLBA (Low) 135 # = (PartitionEntryLBA + 136 # (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE) 137 adcl %ebx, %edx # EDX = Target PartitionEntryLBA (High) 138 139 movw $0xA00, %di # Read to 0x0000:0x0A00 140 movw $1, %bx # Read 1 Block 141 pushw %es 142 call ReadBlocks 143 popw %es 144 145 # **************************************************************************** 146 # Read Target DBR from hard disk to 0x0000:0x7C00 147 # **************************************************************************** 148 popl %edx # EDX = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE 149 addw %dx, %di # DI = Targer PartitionEntryLBA Offset 150 cmpl $0xC12A7328, %es:(%di) # Check for EFI System Partition "C12A7328-F81F-11d2-BA4B-00A0C93EC93B" 151 jne BadGpt 152 cmpl $0x11d2F81F, %es:4(%di) # 153 jne BadGpt 154 cmpl $0xA0004BBA, %es:8(%di) # 155 jne BadGpt 156 cmpl $0x3BC93EC9, %es:0xc(%di) # 157 jne BadGpt 158 159 movl %es:32(%di), %eax # EAX = StartingLBA (Low) 160 movl %es:36(%di), %edx # EDX = StartingLBA (High) 161 movw $0x7C00, %di # Read to 0x0000:0x7C00 162 movw $1, %bx # Read 1 Block 163 call ReadBlocks 164 165 # **************************************************************************** 166 # Transfer control to BootSector - Jump to 0x0000:0x7C00 167 # **************************************************************************** 168 xorw %ax, %ax 169 pushw %ax # PUSH 0x0000 170 movw $0x7c00, %di 171 pushw %di # PUSH 0x7C00 172 retl # JMP 0x0000:0x7C00 173 174 # **************************************************************************** 175 # ReadBlocks - Reads a set of blocks from a block device 176 # 177 # EDX:EAX = Start LBA 178 # BX = Number of Blocks to Read (must < 127) 179 # ES:DI = Buffer to store sectors read from disk 180 # **************************************************************************** 181 182 # si = DiskAddressPacket 183 184 ReadBlocks: 185 pushal 186 pushw %ds 187 xorw %cx, %cx 188 movw %cx, %ds 189 movw $0x600, %bp # bp = 0x600 190 leaw AddressPacket(%bp), %si 191 movb %bl, %ds:2(%si) # 02 = Number Of Block transfered 192 movw %di, %ds:4(%si) # 04 = Transfer Buffer Offset 193 movw %es, %ds:6(%si) # 06 = Transfer Buffer Segment 194 movl %eax, %ds:8(%si) # 08 = Starting LBA (Low) 195 movl %edx, %ds:0xc(%si) # 0C = Starting LBA (High) 196 movb $0x42, %ah # ah = Function 42 197 movb PhysicalDrive(%bp), %dl # dl = Drive Number 198 int $0x13 199 jc BadGpt 200 popw %ds 201 popal 202 ret 203 204 # **************************************************************************** 205 # Address Packet used by ReadBlocks 206 # **************************************************************************** 207 AddressPacket: 208 .byte 0x10 # Size of address packet 209 .byte 0x0 # Reserved. Must be 0 210 .byte 0x1 # Read blocks at a time (To be fixed each times) 211 .byte 0x0 # Reserved. Must be 0 212 .word 0x000 # Destination Address offset (To be fixed each times) 213 .word 0x000 # Destination Address segment (To be fixed each times) 214 AddressPacketLba: 215 .long 0x0,0x0 # Start LBA (To be fixed each times) 216 AddressPacketEnd: 217 218 # **************************************************************************** 219 # ERROR Condition: 220 # **************************************************************************** 221 222 BadGpt: 223 movw $0xb800, %ax 224 movw %ax, %es 225 movw $0x60, %ax 226 movw %ax, %ds 227 leaw %cs:ErrorString, %si 228 movw $10, %cx 229 movw $320, %di 230 rep 231 movsw 232 Halt: 233 jmp Halt 234 235 StartString: 236 .byte 'G', 0x0c, 'P', 0x0c, 'T', 0x0c, ' ', 0x0c, 'S', 0x0c, 't', 0x0c, 'a', 0x0c, 'r', 0x0c, 't', 0x0c, '!', 0x0c 237 ErrorString: 238 .byte 'G', 0x0c, 'P', 0x0c, 'T', 0x0c, ' ', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c 239 240 # **************************************************************************** 241 # PhysicalDrive - Used to indicate which disk to be boot 242 # Can be patched by tool 243 # **************************************************************************** 244 # .org 0x01B6 # Just for passing build. 245 PhysicalDrive: .byte 0x80 246 247 # **************************************************************************** 248 # GptPartitionIndicator - Used to indicate which GPT partition to be boot 249 # Can be patched by tool 250 # **************************************************************************** 251 # .org 0x01B7 # Just for passing build. 252 GptPartitionIndicator: .byte 0 253 254 # **************************************************************************** 255 # Unique MBR signature 256 # **************************************************************************** 257 # .org 0x01B8 # Just for passing build. 258 .ascii "DUET" 259 260 # **************************************************************************** 261 # Unknown 262 # **************************************************************************** 263 # .org 0x01BC # Just for passing build. 264 .word 0 265 266 # **************************************************************************** 267 # PMBR Entry - Can be patched by tool 268 # **************************************************************************** 269 # .org 0x01BE # Just for passing build. 270 .byte 0 # Boot Indicator 271 .byte 0xff # Start Header 272 .byte 0xff # Start Sector 273 .byte 0xff # Start Track 274 .byte 0xee # OS Type 275 .byte 0xff # End Header 276 .byte 0xff # End Sector 277 .byte 0xff # End Track 278 .long 1 # Starting LBA 279 .long 0xFFFFFFFF # End LBA 280 281 # .org 0x01CE # Just for passing build. 282 .long 0,0,0,0 283 # .org 0x01DE # Just for passing build. 284 .long 0,0,0,0 285 # .org 0x01EE # Just for passing build. 286 .long 0,0,0,0 287 288 # **************************************************************************** 289 # Sector Signature 290 # **************************************************************************** 291 292 # .org 0x01FE # Just for passing build. 293 SectorSignature: 294 .word 0xaa55 # Boot Sector Signature 295 296 297 298
