GUID Partition Table

GUID Partition Table Unified Extensible Firmware Interface (UEFI) GUID Partition Table (GPT)

Unified Extensible Firmware Interface • BIOS limitations • 16-bit processor mode • 1MB addressable space • UEFI advantages • UEFI v2.3.1 in April 2011 • Disk device compatibility (GUID Partition Table) • Processor compatibility (x86, x64, ARM)

GUID Partition Table – (1) • Limitation of MBR partition table • Partition record • active(1)、first CHS(3)、type(1)、last CHS(3)、start LBA(4)、size(4) • Maximum capacity • (232-1) x 512 bytes ~ 241 bytes = 2TBytes • GPT • Maximum capacity: 8ZBytes (273 bytes) • Used on some BIOS system

GUID Partition Table – (2) • GPT • LBA 0: Legacy MBR • LBA 1: GPT Header • LBA 2~33: Partition Entries • 128 partitions • LBA 34~: Partitions • LBA -34 ~ -1: Secondary GPT data • Misaligned block • SSD (1K LBA) • WD (4K sector)

GUID Partition Table – (3) • Legacy MBR (LBA 0) • A single partition of type 0xEE, and of whole disk size (max 2T) • For OSes which cannot read GPT: unknown partition, no space • For GPT-aware OSes: check the “protective MBR”

GUID Partition Table – (4) • Partition header table (LBA 1)

GUID Partition Table – (5) • Partition header table (LBA 1) # dd if=/dev/ada0 bs=512 count=1 skip=1 | hd 00000000 45 46 49 20 50 41 52 54 00 00 01 00 5c 00 00 00 |EFI PART....\...| 00000010 e6 f0 27 96 00 00 00 00 01 00 00 00 00 00 00 00 |..'.............| 00000020 2f 60 38 3a 00 00 00 00 22 00 00 00 00 00 00 00 |/`8:....".......| 00000030 0e 60 38 3a 00 00 00 00 7f a3 90 90 46 b4 de 11 |.`8:........F...| 00000040 8e b8 00 21 85 12 22 74 02 00 00 00 00 00 00 00 |...!.."t........| 00000050 80 00 00 00 80 00 00 00 e0 9d 1a 52 00 00 00 00 |...........R....| 00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00000200

GUID Partition Table – (6) • Partition entries (LBA 2~33) • 128 bytes for each partition entry

GUID Partition Table – (7) • Partition type GUID

GUID Partition Table