EFI system partition: Difference between revisions
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== Usage == |
== Usage == |
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=== Windows === |
=== Windows === |
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Microsoft recommends that when partitioning a disk, the EFI System |
Microsoft recommends that when partitioning a disk, the EFI System partition be the first partition on the disk.<ref>{{cite web|url=http://www.microsoft.com/whdc/device/storage/GPT_FAQ.mspx|work=Windows and GPT FAQ|title=EFI System Partition}}</ref> This is not a requirement of the EFI specification itself. On [[Windows XP]] 64-Bit Edition and later, access to the EFI System Partition is obtained by running the <tt>mountvol /s</tt> command. |
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=== Apple–Intel === |
=== Apple–Intel === |
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Revision as of 07:14, 5 July 2012
The EFI System partition is a partition on a data storage device that is used by machines that adhere to the Extensible Firmware Interface. It contains the boot loader programs for all operating systems installed (in other partitions) on the device, device driver files (used by the firmware at boot time) for other devices, and system utility programs that are intended to be run before an operating system is booted.[1]
The EFI System partition is formatted using a variant of the FAT format. The globally unique identifier for the EFI System partition in the GUID Partition Table scheme is C12A7328-F81F-11D2-BA4B-00A0C93EC93B. Its ID in the MBR partition table scheme is 0xEF. Whether a disk contains an EFI System partition is unrelated to the partition table scheme (GUID or MBR) that it uses.
Usage
Windows
Microsoft recommends that when partitioning a disk, the EFI System partition be the first partition on the disk.[2] This is not a requirement of the EFI specification itself. On Windows XP 64-Bit Edition and later, access to the EFI System Partition is obtained by running the mountvol /s command.
Apple–Intel
On Apple–Intel architecture Macintosh computers, the EFI partition is initially blank and not used for booting.[3] However, the EFI partition is used as a staging area for firmware updates;[4] specifically, it places a firmware flash utility (EFI binary) and data file (FD – "Firmware Device"[5]) in the directory EFI/APPLE/FIRMWARE which is then run when rebooting the system in "flash firmware" mode.[6]
If deleted, the system will still boot, and the boot manager will still allow users to choose whether to start a Boot Camp partition or the default Mac OS X, but firmware updates will fail.
See also
References
- ^ EFI specification, version 0.99
- ^ "EFI System Partition". Windows and GPT FAQ.
- ^ rEFIt: Myths and Facts About Intel Macs – Myth: Mac OS X requires a hidden EFI System Partition
- ^ "Firmware updates for Intel-based Macs require a GUID partition scheme". Apple Knowledgebase.
- ^ Zero to OS in a Flash: "Firmware device (FD) is a persistent physical repository that contains firmware code and data."
- ^ ubunto forums: iMac EFI Firmware Update 1.2, September 29th, 2007
External links
- "EFI System Partition Subdirectory Registry". UEFI. — a registry of the subdirectories that lie below the
/EFIdirectory on an EFI System Partition