;------------------------------------------------------------------------------ ;* ;* 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 BLOCK_SIZE EQU 0200h BLOCK_MASK EQU 01ffh BLOCK_SHIFT EQU 9 ; **************************************************************************** ; Code loaded by BIOS at 0x0000:0x7C00 ; **************************************************************************** org 0h Start: ; **************************************************************************** ; Start Print ; **************************************************************************** mov ax,0b800h mov es,ax mov ax, 07c0h mov ds, ax lea si, cs:[StartString] mov cx, 10 mov di, 160 rep movsw ; **************************************************************************** ; Print over ; **************************************************************************** ; **************************************************************************** ; Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600 ; **************************************************************************** xor ax, ax ; AX = 0x0000 mov bx, 07c00h ; BX = 0x7C00 mov bp, 0600h ; BP = 0x0600 mov si, OFFSET RelocatedStart ; SI = Offset(RelocatedStart) mov cx, 0200h ; CX = 0x0200 sub cx, si ; CS = 0x0200 - Offset(RelocatedStart) lea di, [bp+si] ; DI = 0x0600 + Offset(RelocatedStart) lea si, [bx+si] ; BX = 0x7C00 + Offset(RelocatedStart) mov ss, ax ; SS = 0x0000 mov sp, bx ; SP = 0x7C00 mov es,ax ; ES = 0x0000 mov ds,ax ; DS = 0x0000 push ax ; PUSH 0x0000 push di ; PUSH 0x0600 + Offset(RelocatedStart) cld ; Clear the direction flag rep movsb ; Copy 0x0200 bytes from 0x7C00 to 0x0600 retf ; JMP 0x0000:0x0600 + Offset(RelocatedStart) ; **************************************************************************** ; Code relocated to 0x0000:0x0600 ; **************************************************************************** RelocatedStart: ; **************************************************************************** ; Get Driver Parameters to 0x0000:0x7BFC ; **************************************************************************** xor ax,ax ; ax = 0 mov ss,ax ; ss = 0 add ax,1000h mov ds,ax mov sp,07c00h ; sp = 0x7c00 mov bp,sp ; bp = 0x7c00 mov ah,8 ; ah = 8 - Get Drive Parameters Function mov byte ptr [bp+PhysicalDrive],dl ; BBS defines that BIOS would pass the booting driver number to the loader through DL int 13h ; Get Drive Parameters xor ax,ax ; ax = 0 mov al,dh ; al = dh inc al ; MaxHead = al + 1 push ax ; 0000:7bfe = MaxHead mov al,cl ; al = cl and al,03fh ; MaxSector = al & 0x3f push ax ; 0000:7bfc = MaxSector ; **************************************************************************** ; Read GPT Header from hard disk to 0x0000:0x0800 ; **************************************************************************** xor ax, ax mov es, ax ; Read to 0x0000:0x0800 mov di, 0800h ; Read to 0x0000:0x0800 mov eax, 1 ; Read LBA #1 mov edx, 0 ; Read LBA #1 mov bx, 1 ; Read 1 Block push es call ReadBlocks pop es ; **************************************************************************** ; Read Target GPT Entry from hard disk to 0x0000:0x0A00 ; **************************************************************************** cmp dword ptr es:[di], 020494645h ; Check for "EFI " jne BadGpt cmp dword ptr es:[di + 4], 054524150h ; Check for "PART" jne BadGpt cmp dword ptr es:[di + 8], 000010000h ; Check Revision - 0x10000 jne BadGpt mov eax, dword ptr es:[di + 84] ; EAX = SizeOfPartitionEntry mul byte ptr [bp+GptPartitionIndicator] ; EAX = SizeOfPartitionEntry * GptPartitionIndicator mov edx, eax ; EDX = SizeOfPartitionEntry * GptPartitionIndicator shr eax, BLOCK_SHIFT ; EAX = (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE and edx, BLOCK_MASK ; EDX = Targer PartitionEntryLBA Offset ; = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE push edx mov ecx, dword ptr es:[di + 72] ; ECX = PartitionEntryLBA (Low) mov ebx, dword ptr es:[di + 76] ; EBX = PartitionEntryLBA (High) add eax, ecx ; EAX = Target PartitionEntryLBA (Low) ; = (PartitionEntryLBA + ; (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE) adc edx, ebx ; EDX = Target PartitionEntryLBA (High) mov di, 0A00h ; Read to 0x0000:0x0A00 mov bx, 1 ; Read 1 Block push es call ReadBlocks pop es ; **************************************************************************** ; Read Target DBR from hard disk to 0x0000:0x7C00 ; **************************************************************************** pop edx ; EDX = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE add di, dx ; DI = Targer PartitionEntryLBA Offset cmp dword ptr es:[di], 0C12A7328h ; Check for EFI System Partition "C12A7328-F81F-11d2-BA4B-00A0C93EC93B" jne BadGpt cmp dword ptr es:[di + 4], 011d2F81Fh ; jne BadGpt cmp dword ptr es:[di + 8], 0A0004BBAh ; jne BadGpt cmp dword ptr es:[di + 0ch], 03BC93EC9h ; jne BadGpt mov eax, dword ptr es:[di + 32] ; EAX = StartingLBA (Low) mov edx, dword ptr es:[di + 36] ; EDX = StartingLBA (High) mov di, 07C00h ; Read to 0x0000:0x7C00 mov bx, 1 ; Read 1 Block call ReadBlocks ; **************************************************************************** ; Transfer control to BootSector - Jump to 0x0000:0x7C00 ; **************************************************************************** xor ax, ax push ax ; PUSH 0x0000 mov di, 07c00h push di ; PUSH 0x7C00 retf ; 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: pushad push ds xor cx, cx mov ds, cx mov bp, 0600h ; bp = 0x600 lea si, [bp + OFFSET AddressPacket] ; DS:SI = Disk Address Packet mov BYTE PTR ds:[si+2],bl ; 02 = Number Of Block transfered mov WORD PTR ds:[si+4],di ; 04 = Transfer Buffer Offset mov WORD PTR ds:[si+6],es ; 06 = Transfer Buffer Segment mov DWORD PTR ds:[si+8],eax ; 08 = Starting LBA (Low) mov DWORD PTR ds:[si+0ch],edx ; 0C = Starting LBA (High) mov ah, 42h ; ah = Function 42 mov dl,byte ptr [bp+PhysicalDrive] ; dl = Drive Number int 13h jc BadGpt pop ds popad ret ; **************************************************************************** ; Address Packet used by ReadBlocks ; **************************************************************************** AddressPacket: db 10h ; Size of address packet db 00h ; Reserved. Must be 0 db 01h ; Read blocks at a time (To be fixed each times) db 00h ; Reserved. Must be 0 dw 0000h ; Destination Address offset (To be fixed each times) dw 0000h ; Destination Address segment (To be fixed each times) AddressPacketLba: dd 0h, 0h ; Start LBA (To be fixed each times) AddressPacketEnd: ; **************************************************************************** ; ERROR Condition: ; **************************************************************************** BadGpt: mov ax,0b800h mov es,ax mov ax, 060h mov ds, ax lea si, cs:[ErrorString] mov cx, 10 mov di, 320 rep movsw Halt: jmp Halt StartString: db 'G', 0ch, 'P', 0ch, 'T', 0ch, ' ', 0ch, 'S', 0ch, 't', 0ch, 'a', 0ch, 'r', 0ch, 't', 0ch, '!', 0ch ErrorString: db 'G', 0ch, 'P', 0ch, 'T', 0ch, ' ', 0ch, 'E', 0ch, 'r', 0ch, 'r', 0ch, 'o', 0ch, 'r', 0ch, '!', 0ch ; **************************************************************************** ; PhysicalDrive - Used to indicate which disk to be boot ; Can be patched by tool ; **************************************************************************** org 01B6h PhysicalDrive db 80h ; **************************************************************************** ; GptPartitionIndicator - Used to indicate which GPT partition to be boot ; Can be patched by tool ; **************************************************************************** org 01B7h GptPartitionIndicator db 0 ; **************************************************************************** ; Unique MBR signature ; **************************************************************************** org 01B8h db 'DUET' ; **************************************************************************** ; Unknown ; **************************************************************************** org 01BCh dw 0 ; **************************************************************************** ; PMBR Entry - Can be patched by tool ; **************************************************************************** org 01BEh db 0 ; Boot Indicator db 0ffh ; Start Header db 0ffh ; Start Sector db 0ffh ; Start Track db 0eeh ; OS Type db 0ffh ; End Header db 0ffh ; End Sector db 0ffh ; End Track dd 1 ; Starting LBA dd 0FFFFFFFFh ; End LBA org 01CEh dd 0, 0, 0, 0 org 01DEh dd 0, 0, 0, 0 org 01EEh dd 0, 0, 0, 0 ; **************************************************************************** ; Sector Signature ; **************************************************************************** org 01FEh SectorSignature: dw 0aa55h ; Boot Sector Signature end