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I have a Samsung Notebook with a 1TB drive. It has Windows 10 installed alongside a Linux Distro.
All my data resides on the Windows Partition,which forces me to disable "Fast Startup", so Linux can read the partition.
The problem with this is that it makes Windows take forever to boot, So I decided to start fresh: Completely format my HD, reinstall Windows, reinstall Linux and create a data partition, so all my data will be centralized in a single place, accessible by both OSes
But the question is: Should I Format my EFI partition?
Looking around tells me two things :

  • Formatting the EFI partiton WILL brick a computer, to the point it won't even POST(Link 1,Link 2)
  • Formatting the EFI partition WILL NOT brick the computer, instead it just won't be able to boot to anything, requiring a OS (like Windows) to create the EFI partition(Link 1, Link 2)

So, is formatting the EFI partition safe, or should I just delete all partitions and leave the EFI one untouched during the reinstall?

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  • Having a data partition won't help; you still have to disable fast startup.
    – psusi
    May 1, 2018 at 18:16
  • I managed to achieve what I wanted, by unmounting the Data partition using a batch file before each shutdown,and remounting it on boot. Somewhat clunky solution,but functional. Answer explaining how to use the 'mountvol' command
    – LiveLM
    May 10, 2018 at 23:13
  • Ahh, I didn't think Windows could unmount a volume.
    – psusi
    May 11, 2018 at 20:21

1 Answer 1

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Your first two links are not about formatting the EFI partition, but about deleting the EFI NVRAM variables. These variables are not located in the EFI partition, but in the non-volatile memory of the motherboard - the same place that holds the system's BIOS settings.

In Windows, if you have a system that is booting in full UEFI mode, you can open a command prompt as an administrator, and then type bcdedit /enum firmware to see the some of the boot-related EFI variables and their values. But the presentation style hides the fact that there can be many more of these variables. If your system supports Secure Boot, there will be some standardized EFI variables related to that; if your firmware vendor so decided, all the "BIOS settings" might be accessible as UEFI variables.

In /sys/firmware/efi/efivars, Linux offers an interface that reveals all those variables and allows the root user to modify them (as much as the firmware allows). And turns out that some early UEFI firmware versions will obey the command to delete all the UEFI variables, but aren't programmed to recover from the aftermath of such a situation.

If those systems used the same type of battery-backed NVRAM as most desktops tend to do as EFI variable storage, those systems probably would have been/will be just as bricked when the system board's battery runs out. So the firmware bug that results in bricking actually works as a planned obsolescence implement too - unless an UEFI firmware update fixes it before the batteries get critically low.

Formatting the EFI partition should be safe, as the system should certainly remain usable even if a failing system disk needs to be replaced. But if you have a system model which is known to have a buggy UEFI firmware, I'd check the firmware versions, and if newer versions are available, would probably upgrade first just to be safe, especially if firmware release notes say that the new version fixes important bugs.

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