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I'm trying to install Windows 8 through a bootable USB flash drive, in UEFI Mode. However, while it does work when the drive is formatted as FAT for some versions of Windows 8, the version I want to install has a install.wim file bigger than 4Gb, so I have to use an NTFS file system on the flash drive, but I cannot boot in UEFI mode from it. In both cases I use a GPT partition table. Is booting from NTFS not possible in UEFI mode (strange, as is the file system used by Windows) or am I doing something wrong?

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2 Answers 2

up vote 4 down vote accepted

From the Wikipedia article on UEFI:

The UEFI specification explicitly requires support for FAT32 for system partitions, and FAT12/FAT16 for removable media; specific implementations may support other file systems.

Personally I've yet to encounter any motherboard manufacturer who has implemented NTFS boot support in their UEFI modules.

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First, what reads the install.wim file you mention? If it's read after the Windows kernel has taken control of the system, it shouldn't be necessary to put the file on the EFI System Partition (ESP), which must be FAT. Once the Windows kernel has loaded (and loaded its filesystem drivers, if they're in separate files), Windows should be able to read NTFS volumes just fine. My suspicion is that this is how it works; however, I don't know enough about the Windows installer to suggest how to point it to install.wim on a specific partition.

OTOH, if install.wim must be read while the EFI is still running, there may be a way to do it. The Clover EFI Tools package (available from this forum thread) includes an NTFS driver for EFI; however, I don't know the provenance of that driver, so I'm providing this pointer only reluctantly. To use it, you'd need to either load it manually from an EFI shell or use rEFInd to launch it automatically. I can't offer any specific advice on how to partition your disk or get the Windows installer to launch and recognize the files on the NTFS volume.

It's conceivable you could get it to work with another filesystem, too. rEFInd includes drivers for ReiserFS, ext2fs, ext3fs, and HFS+, all of which support over-4GiB files. The trouble, of course, is that Windows doesn't support these filesystems, so once Windows takes over, it would lose access to those files. Creating two partitions -- one with a Linux or OS X filesystem and one with NTFS -- and putting identical files on them might be a workaround.

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