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An EFI system partition that is present on a hard disk must contain an EFI defined directory in the root
directory. This directory is named EFI. All OS loaders and applications will be stored in subdirectories
below EFI. Applications that are loaded by other applications or drivers are not required to be stored in
any specific location in the EFI system partition. The choice of the subdirectory name is up to the vendor,
but all vendors must pick names that do not collide with any other vendor’s subdirectory name. This
applies to system manufacturers, operating system vendors, BIOS vendors, and third party tool vendors,
or any other vendor that wishes to install files on an EFI system partition. There must also only be one
executable EFI image for each supported processor architecture in each vendor subdirectory. This
guarantees that there is only one image that can be loaded from a vendor subdirectory by the EFI Boot
Manager. If more than one executable EFI image is present, then the boot behavior for the system will
not be deterministic. There may also be an optional vendor subdirectory called BOOT.
This directory contains EFI images that aide in recovery if the boot selections for the software installed on
the EFI system partition are ever lost. Any additional UEFI-compliant executables must be in
subdirectories below the vendor subdirectory. The following is a sample directory structure for an EFI
system partition present on a hard disk.
For removable media devices there must be only one UEFI-compliant system partition, and that partition
must contain an UEFI-defined directory in the root directory. The directory will be named EFI. All OS
loaders and applications will be stored in a subdirectory below EFI called BOOT. There must only be one
executable EFI image for each supported processor architecture in the BOOT directory. For removable
media to be bootable under EFI, it must be built in accordance with the rules laid out in Section 3.5.1.1.
This guarantees that there is only one image that can be automatically loaded from a removable media
device by the EFI Boot Manager. Any additional EFI executables must be in directories other than BOOT. |
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