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I was curious and poking around my Windows 8 system. Per Wikipedia's entry on UEFI

Boot loaders can also be automatically detected by the UEFI firmware, to enable booting from removable devices. Auto-detection relies on a standardized file path to the operating system loader, depending on the actual architecture to boot. Format of the file path is defined as EFI_SYSTEM_PARTITION/BOOT/BOOTMACHINE_TYPE_SHORT_NAME.EFI, e.g. /efi/BOOT/BOOTX64.EFI

I decided to mount my EFI system partition and check it out.

The only remotely relevant file I see is M:\boot\boot.sdi

In M:\boot there is also an en-us (which contains bootsect.exe.mui), fonts, resources folder as well as bcd, etfsboot.exe, and memtest.exe

Since there is no BOOT*.efi how does UEFI know where to find the boot files? Also the "boot" folder is lower cased and per Wiki it seems it should be "BOOT"

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Are you positive your computer is using UEFI and not legacy support? Verify your hdd is a GPT disk – Ramhound Jan 6 '14 at 0:31
Yes it's booting into UEFI. I have UEFI enabled in the BIOS. I'm partitioned GPT and the System partition is designated properly as an EFI SYSTEM PARTITION – uefimystery23asdf Jan 6 '14 at 0:35

Note that the exact phrase is

Boot loaders can also be automatically detected by the UEFI firmwares

Emphasis mine. Earlier on in that section, it states that:

The UEFI specification defines a "boot manager", a firmware policy engine that is in charge of loading the operating system loader and all necessary drivers. The boot configuration is controlled by a set of global NVRAM variables, including boot variables that indicate the paths to the loaders.

Again, emphasis mine. The EFI "BIOS" knows where the correct loader is because Windows, during installation, told it where to look and it is evidently in a different location than the default.

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On UEFI System Partition paths begin with \EFI !

For example:




"\EFI\Boot" folder/directory stores the default fallback boot loader.

\EFI\'Company' - are also reserved names.

'Company' folder can have any structure (sub, sub-sub folders). The corresponding boot entry has the correct path to boot loader file, e.g. "\EFI\Microsoft\Boot\bootmgfw.efi"

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