#------------------------------------------------------------------------------ #* #* Copyright 2006 - 2007, 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. #* #* gpt.asm #* #* Abstract: #* #------------------------------------------------------------------------------ #.MODEL small # .dosseg .stack: .486p: .code: .equ BLOCK_SIZE, 0x0200 .equ BLOCK_MASK, 0x01ff .equ BLOCK_SHIFT, 9 # **************************************************************************** # Code loaded by BIOS at 0x0000:0x7C00 # **************************************************************************** .org 0x00 Start: # **************************************************************************** # Start Print # **************************************************************************** movw $0xb800, %ax movw %ax, %es movw $0x7c0, %ax movw %ax, %ds leaw %cs:StartString, %si movw $10, %cx movw $160, %di rep movsw # **************************************************************************** # Print over # **************************************************************************** # **************************************************************************** # Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600 # **************************************************************************** xorw %ax, %ax # AX = 0x0000 movw $0x7c00, %bx # BX = 0x7C00 movw $0x600, %bp # BP = 0x0600 movw RelocatedStart, %si # SI = Offset(RelocatedStart) movw $0x200, %cx # CX = 0x0200 subw %si, %cx # CS = 0x0200 - Offset(RelocatedStart) leaw (%bp,%si,), %di # DI = 0x0600 + Offset(RelocatedStart) leaw (%bx,%si,), %si # BX = 0x7C00 + Offset(RelocatedStart) movw %ax, %ss # SS = 0x0000 movw %bx, %sp # SP = 0x7C00 movw %ax, %es # ES = 0x0000 movw %ax, %ds # DS = 0x0000 pushw %ax # PUSH 0x0000 pushw %di # PUSH 0x0600 + Offset(RelocatedStart) cld # Clear the direction flag rep movsb # Copy 0x0200 bytes from 0x7C00 to 0x0600 retl # JMP 0x0000:0x0600 + Offset(RelocatedStart) # **************************************************************************** # Code relocated to 0x0000:0x0600 # **************************************************************************** RelocatedStart: # **************************************************************************** # Get Driver Parameters to 0x0000:0x7BFC # **************************************************************************** xorw %ax, %ax # ax = 0 movw %ax, %ss # ss = 0 addw $0x1000, %ax movw %ax, %ds movw $0x7c00, %sp # sp = 0x7c00 movw %sp, %bp # bp = 0x7c00 movb $8, %ah # ah = 8 - Get Drive Parameters Function movb %dl, PhysicalDrive(%bp) # BBS defines that BIOS would pass the booting driver number to the loader through DL int $0x13 # Get Drive Parameters xorw %ax, %ax # ax = 0 movb %dh, %al # al = dh incb %al # MaxHead = al + 1 pushw %ax # 0000:7bfe = MaxHead movb %cl, %al # al = cl andb $0x3f, %al # MaxSector = al & 0x3f pushw %ax # 0000:7bfc = MaxSector # **************************************************************************** # Read GPT Header from hard disk to 0x0000:0x0800 # **************************************************************************** xorw %ax, %ax movw %ax, %es # Read to 0x0000:0x0800 movw $0x800, %di # Read to 0x0000:0x0800 movl $1, %eax # Read LBA #1 movl $0, %edx # Read LBA #1 movw $1, %bx # Read 1 Block pushw %es call ReadBlocks popw %es # **************************************************************************** # Read Target GPT Entry from hard disk to 0x0000:0x0A00 # **************************************************************************** cmpl $0x20494645, %es:(%di) # Check for "EFI " jne BadGpt cmpl $0x54524150, %es:4(%di) # Check for "PART" jne BadGpt cmpl $0x00010000, %es:8(%di) # Check Revision - 0x10000 jne BadGpt movl %es:84(%di), %eax # EAX = SizeOfPartitionEntry mulb GptPartitionIndicator(%bp) # EAX = SizeOfPartitionEntry * GptPartitionIndicator movl %eax, %edx # EDX = SizeOfPartitionEntry * GptPartitionIndicator shrl $BLOCK_SHIFT, %eax # EAX = (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE andl $BLOCK_MASK, %edx # EDX = Targer PartitionEntryLBA Offset # = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE pushl %edx movl %es:72(%di), %ecx # ECX = PartitionEntryLBA (Low) movl %es:76(%di), %ebx # EBX = PartitionEntryLBA (High) addl %ecx, %eax # EAX = Target PartitionEntryLBA (Low) # = (PartitionEntryLBA + # (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE) adcl %ebx, %edx # EDX = Target PartitionEntryLBA (High) movw $0xA00, %di # Read to 0x0000:0x0A00 movw $1, %bx # Read 1 Block pushw %es call ReadBlocks popw %es # **************************************************************************** # Read Target DBR from hard disk to 0x0000:0x7C00 # **************************************************************************** popl %edx # EDX = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE addw %dx, %di # DI = Targer PartitionEntryLBA Offset cmpl $0xC12A7328, %es:(%di) # Check for EFI System Partition "C12A7328-F81F-11d2-BA4B-00A0C93EC93B" jne BadGpt cmpl $0x11d2F81F, %es:4(%di) # jne BadGpt cmpl $0xA0004BBA, %es:8(%di) # jne BadGpt cmpl $0x3BC93EC9, %es:0xc(%di) # jne BadGpt movl %es:32(%di), %eax # EAX = StartingLBA (Low) movl %es:36(%di), %edx # EDX = StartingLBA (High) movw $0x7C00, %di # Read to 0x0000:0x7C00 movw $1, %bx # Read 1 Block call ReadBlocks # **************************************************************************** # Transfer control to BootSector - Jump to 0x0000:0x7C00 # **************************************************************************** xorw %ax, %ax pushw %ax # PUSH 0x0000 movw $0x7c00, %di pushw %di # PUSH 0x7C00 retl # JMP 0x0000:0x7C00 # **************************************************************************** # ReadBlocks - Reads a set of blocks from a block device # # EDX:EAX = Start LBA # BX = Number of Blocks to Read (must < 127) # ES:DI = Buffer to store sectors read from disk # **************************************************************************** # si = DiskAddressPacket ReadBlocks: pushal pushw %ds xorw %cx, %cx movw %cx, %ds movw $0x600, %bp # bp = 0x600 leaw AddressPacket(%bp), %si movb %bl, %ds:2(%si) # 02 = Number Of Block transfered movw %di, %ds:4(%si) # 04 = Transfer Buffer Offset movw %es, %ds:6(%si) # 06 = Transfer Buffer Segment movl %eax, %ds:8(%si) # 08 = Starting LBA (Low) movl %edx, %ds:0xc(%si) # 0C = Starting LBA (High) movb $0x42, %ah # ah = Function 42 movb PhysicalDrive(%bp), %dl # dl = Drive Number int $0x13 jc BadGpt popw %ds popal ret # **************************************************************************** # Address Packet used by ReadBlocks # **************************************************************************** AddressPacket: .byte 0x10 # Size of address packet .byte 0x0 # Reserved. Must be 0 .byte 0x1 # Read blocks at a time (To be fixed each times) .byte 0x0 # Reserved. Must be 0 .word 0x000 # Destination Address offset (To be fixed each times) .word 0x000 # Destination Address segment (To be fixed each times) AddressPacketLba: .long 0x0,0x0 # Start LBA (To be fixed each times) AddressPacketEnd: # **************************************************************************** # ERROR Condition: # **************************************************************************** BadGpt: movw $0xb800, %ax movw %ax, %es movw $0x60, %ax movw %ax, %ds leaw %cs:ErrorString, %si movw $10, %cx movw $320, %di rep movsw Halt: jmp Halt StartString: .byte 'G', 0x0c, 'P', 0x0c, 'T', 0x0c, ' ', 0x0c, 'S', 0x0c, 't', 0x0c, 'a', 0x0c, 'r', 0x0c, 't', 0x0c, '!', 0x0c ErrorString: .byte 'G', 0x0c, 'P', 0x0c, 'T', 0x0c, ' ', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c # **************************************************************************** # PhysicalDrive - Used to indicate which disk to be boot # Can be patched by tool # **************************************************************************** # .org 0x01B6 # Just for passing build. PhysicalDrive: .byte 0x80 # **************************************************************************** # GptPartitionIndicator - Used to indicate which GPT partition to be boot # Can be patched by tool # **************************************************************************** # .org 0x01B7 # Just for passing build. GptPartitionIndicator: .byte 0 # **************************************************************************** # Unique MBR signature # **************************************************************************** # .org 0x01B8 # Just for passing build. .ascii "DUET" # **************************************************************************** # Unknown # **************************************************************************** # .org 0x01BC # Just for passing build. .word 0 # **************************************************************************** # PMBR Entry - Can be patched by tool # **************************************************************************** # .org 0x01BE # Just for passing build. .byte 0 # Boot Indicator .byte 0xff # Start Header .byte 0xff # Start Sector .byte 0xff # Start Track .byte 0xee # OS Type .byte 0xff # End Header .byte 0xff # End Sector .byte 0xff # End Track .long 1 # Starting LBA .long 0xFFFFFFFF # End LBA # .org 0x01CE # Just for passing build. .long 0,0,0,0 # .org 0x01DE # Just for passing build. .long 0,0,0,0 # .org 0x01EE # Just for passing build. .long 0,0,0,0 # **************************************************************************** # Sector Signature # **************************************************************************** # .org 0x01FE # Just for passing build. SectorSignature: .word 0xaa55 # Boot Sector Signature