GPT FAQ - lzeng14/tianocore GitHub Wiki

Frequently asked questins about GPT

Table of Contents Are there tools to setup and create the EFI GPT partition? Can an OS install be converted to EFI? In reference to the figure in the UEFI 2.x Section 5.3.1 where does the Logical Block Address (LBA) LBAn exist on a disk? In reference to UEFI 2.x section 5.3 GUID Partition Table (GPT) any impact to per due to GPT? When installing a UEFI aware OS when do you create the GPT Partitions? Why would I need it (UEFI aware OS)?

Are there tools to setup and create the EFI GPT partition?

Yes win7 installations set up GPT. Intel EFI technology has ‘partition utilities’ download: http://www.intel.com/technology/efi

Can an OS install be converted to EFI?

No, this must be on installation with a clean disk.

In reference to the figure in the UEFI 2.x Section 5.3.1 where does the Logical Block Address (LBA) LBAn exist on a disk?

LBAn is the last logical block on a disk and also stores the Backup GUID Partition Table Header’s fields. See section 5.3 UEFI 2.x for more details

In reference to UEFI 2.x section 5.3 GUID Partition Table (GPT) any impact to per due to GPT?

There are advantages for formatting hard drives with GPT:

128 Bit Unique Identifier and unique serial number
Supports many partitions unlike MBR
Uses a primary and backup table for redundancy.
Support for greater than 2.2TB hard drives

When installing a UEFI aware OS when do you create the GPT Partitions?

If there is not a GPT partition then this must done on install. UEFI needs the GPT partition to create UEFI aware OS

Why would I need it (UEFI aware OS)?

To get the benefits of UEFI with the OS. One benefit is >2.2 TB hard drive support.