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#------------------------------------------------------------------------------
#*
#* 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
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