Annex a | Western Digital T13/2132-D specs

June 23, 2010

T13/2132-D Revision 3

Annex A

(informative)

Hybrid MBR boot

A.1 Hybrid MBR boot overview

This annex describes how MBR boot code called hybrid MBR boot code may be constructed to support a GPT disk layout (see UEFI-2.3) in a legacy BIOS system.

A.2 GPT support for hybrid MBR boot code

When using hybrid MBR boot code, the GPT disk layout includes one GPT partition with the Legacy BIOS Bootable bit set to one in the Attributes field (see UEFI-2.3).

The Protective MBR defined in UEFI-2.3 is modified as shown in table A.1 to include hybrid MBR boot code.

Table A.1 — Protective MBR with hybrid MBR boot code

Mnemonic	Byte Offset	Byte Length	Contents
Boot Code	0	440	Hybrid MBR boot code (see A.3)

Unique MBR Disk Signature	440	4	See UEFI-2.3

Unknown	444	2	See UEFI-2.3

Partition Record	446	16 * 4	See UEFI-2.3

Signature	510	2	See UEFI-2.3

Reserved	512	Logical Block Size - 512	See UEFI-2.3

Figure A.1 shows an example of a GPT disk layout with hybrid MBR boot code.

		Primary	UEFI	Partition	Partition	Partition	Backup
	Protective	Primary	system				Backup
	Protective	GPT	system				GPT
	MBR with		partition
	hybrid
	MBR boot
	code			GPT Protective partition
	LBA 0	LBA 1					End of disk

Figure A.1 — GPT disk layout with hybrid MBR boot code example

Working Draft Enhanced Disk Drive - 4 (EDD-4)

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Western Digital T13/2132-D manual Annex a, Hybrid MBR boot Hybrid MBR boot overview, GPT support for hybrid MBR boot code

Contents

Revision June 23 Information technology Enhanced Disk Drive 4 EDD-4 Working Draft Enhanced Disk Drive 4 EDD-4 Points of ContactT13/2132-D Revision 3June 23 June 23 T13/2132-D Revision Draft T13/2132-D Revision June 23 American National Standard New Capabilities added to EDD-4 Document Status Contents Working Draft Enhanced Disk Drive 4 EDD-4 Vii Viii Working Draft Enhanced Disk Drive 4 EDD-4 Output Parameters Tables Figures Introduction Foreword Xii Working Draft Enhanced Disk Drive 4 EDD-4 American National Standard for Information Technology ScopeBSR Incits ATA8-APT ATA8-AST Approved Ansi References Name Normative references GeneralApproved references References Under Development Name Project Number References under developmentOther references June 23 T13/2132-D Revision Abbreviation Meaning Symbols and abbreviationsMaster Boot Record MBR The first LBA on a disk Conventions Ordered lists PrecedenceLists Lists overview Unordered lists Numbering T13/2132-D Revision June 23 Keywords Bit conventions Register and CF ContentsInterrupt Services and Functions Numbering conventions French English This standard QWord at word offset n ByteWord at offset n DWord at word offset n Byte Value ATA string byte swapping Word Byte Character in stringATA firmware revision example Word Overview Bit Description 8GB INT 13h Functions Conventional FunctionsConventional Register Definitions Register Description Conventional Function Definitions Function a Description Function Description 8GB INT 13h Functions OverviewData Structure Extended Function Definitions T13/2132-D Revision June 23 Device Address Packet Offset INT 13h Interface Subsets Fixed Disk Access SubsetFixed Disk Access Function Code Removable Media EDD Support Function Code Locking and Ejecting Function CodeEnhanced Disk Drive EDD Support Subset ISO 9660 CD Layout Working Draft Enhanced Disk Drive 4 EDD-4 CD/DVD Boot Overview System Area Unused Emulation Process Boot Methods Floppy Geometries Type Cylinders Heads Sectors No Emulation BootFloppy Boot Hard Drive Boot CD/DVD Format Boot Volume Descriptor BVDBoot Volume Descriptor Offset Type Description T13/2132-D Revision June 23 Validation Entry Section Header June 23 T13/2132-D Revision Initial/Default Entry 00h Byte Header ID Type Description June 23 T13/2132-D Revision Section Entry T13/2132-D Revision June 23 Section Entry Extension INT 13h Function Definitions Overview Reset Disk Subsystem FN 00h Get Status of Last Operation FN 01h Read Sectors into Memory FN 02h Write Sectors From Memory FN 03h Verify Sectors FN 04h Get Drive Parameters FN 08h Read Buffer FN 0Eh Write Buffer FN 0Fh Value Description Get Disk Type FN 15h Set Media Type FN 18h Park Heads FN 19h Identify Device Information FN 25h Interface Support Bit Map Description Check Extensions Present FN 41h Extended Read FN 42h Extended Write FN 43h Verify Sectors FN 44h Lock/Unlock Media FN 45h Eject Removable Media FN 46h Result Buffer Get Device Parameters FN 48h Ascii Interface Path Definitions part 1 Host Bus Type Offset T13/2132-D Revision June 23 Interface Path Device Path Definition 00h ATA Device 01h 02h..FFh Reserved Byte Word DWord QWord Byte Port number Device parameter table extension Offset 2-3 control port base Offset 5 Bios use only Bios use only Offset 6 IRQ numberOffset 7 READ/WRITE Multiple command block count Offset 0-1 I/O port base Offset 9 PIO type Offset 10-11 Bios selected hardware specific option flagsBit 7 32-bit transfer mode Bit 8 Atapi device uses command packet interrupt Bit 11 Ultra DMA Bit 13h 48-bit LBA addressing enabledJune 23 T13/2132-D Revision Bits 9-10 translation type Translation Type Bits Description Get Extended Media Change Status FN 49h Initiate Disk Emulation FN 4Ah Value Emulation Working Draft Enhanced Disk Drive 4 EDD-4 Terminate Disk Emulation FN 4Bh Initiate Disk Emulation & Boot FN 4Ch CD Command Packet Return Boot Catalog FN 4Dh Hardware Configuration Sub-Functions Set Hardware Configuration FN 4Eh Formatted Command Packet Offset Type Description Send Packet Command FN 50h Formatted Protocol Specific Data T13/2132-D Revision June 23 Output Parameters Security Protocol Commands FN 51h INT 15h Removable Media Eject Annex a Hybrid MBR boot Hybrid MBR boot overviewGPT support for hybrid MBR boot code Hybrid MBR boot code EAX Hybrid MBR boot code endeavor procedure Hybrid VBR boot code