[SOLVED] "Convert" NTFS EFI partition to FAT32

BaronArron · 2015-07-30 22:45:29

Hello.

I very recently built a new PC and planned on dual booting Windows 10 and Arch. I read the beginners guide and was comfortable with the procedure, so I started by installing Windows 10 first and got the system up and running.

The problem is that when I began setting up Arch, I noticed that my EFI partition (which was created by the Windows 10 installer) is formatted as NTFS! This means that I can't replace the bootloader with rEFind or some such. I think previous versions of Windows defaulted to FAT32 maybe, because I've searched for this issue and can't find any solution.

My idea is to use gdisk to backup the GPT table to a file; format the EFI partition using mkfs.vfat and finally restore the GPT table using gdisk and the back-up I created initially.

Does this method sound plausible? I really have no experience using gdisk, or EFI for that matter (all previous PCs have used MBR).

Thanks for any help offered.

Last edited by BaronArron (2015-07-31 23:40:19)

Soukyuu · 2015-07-31 00:20:56

Restoring the GPT table will probably make it state that the EFI partition is NTFS again. I think you should be able to just backup the contents of the partition, format it as FAT32 and stuff the files back in. Considering you want to install a non-windows bootloader in there anyway, I don't think you should run into problems.

That said, the UEFI PCs I have refuses to boot from an NTFS stick in UEFI mode. So from what I'm gathering, an EFI partition can NOT be formatted with NTFS to count as one.
Did you explicitly boot in UEFI mode to install win10 (Selecting the UEFI: yourbootmedia boot entry, and not the yourbootmedia boot entry)? If not, then the EFI partition you see is most likely the usual "system reserved" partition containing the boot files and a recovery environment.

severach · 2015-07-31 07:13:07

Windows XP was the last OS that would tolerate installation to FAT32. NTFS is mandatory for boot drives for Vista onward. Data drives can be FAT32.

Soukyuu · 2015-07-31 12:06:57

EFI drive != windows boot drive.
On an UEFI system, windows creates three partitions: EFI (fat32), System Reserved (NTFS) and the actual system partition (NTFS, mounted as C:\)

BaronArron · 2015-07-31 13:18:02

Hmm, interesting. Yes, you're right: the EFI spec states that the boot drive needs to be FAT, so perhaps it isn't doing what I expected.

I installed Windows 10 using the Windows Media Creation tool (which may have been a mistake - it seems the recommended method is to use dd or Rufus). Then, when I got to the Win10 installer, I opened a command prompt, launched Diskutil and set the partition system to be GPT.

After this, I used the 'Advanced' Windows install method: I selected the unallocated space and clicked 'New' to create a 400GB partition. This (IIRC) created 2 partitions automatically. I then created a third partition reserved for Linux.

From what you've mentioned, Windows should create 3 partitions if it's using EFI (I assumed just enabling GPT partition system would automatically mean I'm using EFI). Because I only got two, I could still be using legacy booting?

I'll investigate further when I get home from work. I never checked my BIOS settings although I believe Secure Boot is enabled because I had to use the Hash Tool when booting the Arch live USB.

Thanks!

Last edited by BaronArron (2015-07-31 13:19:49)

BaronArron · 2015-07-31 18:38:52

I've just got home and checked the value in msinfo32 and indeed the BIOS mode is set to 'Legacy'.

This begs the question: I thought Windows was only capable of UEFI if the partition type is GPT?? I explicitly set the partition type to GPT before I installed Windows so either this restriction doesn't apply anymore or WIndows silently converted back to MBR.

Head_on_a_Stick · 2015-07-31 21:34:23

What is the output of:

# parted -l

BaronArron · 2015-07-31 23:40:04

Unfortunately I've already wiped my system and repartitioned.

Here's what I think happened:

Either the Windows 10 USB maker tool didn't create a proper UEFI bootable USB stick, or I erroneously didn't select the UEFI boot option when initially installing Windows.

I manually converted the drive type to be GPT before installing, but because I wasn't in UEFI mode, when I created the partitions in Windows installer, it reverted back to MBR.

I've managed to reinstall Windows 10 in UEFI mode now, so all is well. I'll see if I can mark this post as resolved.

Arch Linux

#1 2015-07-30 22:45:29

[SOLVED] "Convert" NTFS EFI partition to FAT32

#2 2015-07-31 00:20:56

Re: [SOLVED] "Convert" NTFS EFI partition to FAT32

#3 2015-07-31 07:13:07

Re: [SOLVED] "Convert" NTFS EFI partition to FAT32

#4 2015-07-31 12:06:57

Re: [SOLVED] "Convert" NTFS EFI partition to FAT32

#5 2015-07-31 13:18:02

Re: [SOLVED] "Convert" NTFS EFI partition to FAT32

#6 2015-07-31 18:38:52

Re: [SOLVED] "Convert" NTFS EFI partition to FAT32

#7 2015-07-31 21:34:23

Re: [SOLVED] "Convert" NTFS EFI partition to FAT32

#8 2015-07-31 23:40:04

Re: [SOLVED] "Convert" NTFS EFI partition to FAT32

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