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I have just installed Kubuntu 22.04 (dual boot with Windows 10 on the same disk). During the installation of Kubuntu, I created a partition (i.e. partition 7) to use as EFI system partition and marked it as device for boot loader installation. Now, I realize that the boot loader is not in partition 7, but in partition 1 which previously belongs to Windows.

enter image description here

Things in partition 1:

enter image description here

Things in partition 7:

enter image description here

Why does it happen?

Edit: about the installation of Kubuntu, in the disk setup step, I chose to install manually. I created an EFI partition (partition 7) like in the image below, the "device for boot loader installation:" option was set partition 7. I also created 2 more partitions: one is for "swap area", and the other is for "ext4 journaling file system", the mount point is /.

(I didn't capture the setup image when I was installing, so I got this image from Internet) enter image description here

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  • You need to specify how exactly you installed Kubuntu.
    – harrymc
    Commented Sep 4, 2023 at 14:52
  • @harrymc I have edited, please see the post.
    – Becker
    Commented Sep 4, 2023 at 15:15
  • Since Windows 10 was already installed, then there was already an EFI partition. Why would you create a second one?
    – harrymc
    Commented Sep 4, 2023 at 15:26
  • @harrymc I don't have much knowledge about this so I decided to follow a guide on Internet. An answer about "why I don't need to have a second ESP" and related things like: EFI, booting, partitioning,.. would be great =))
    – Becker
    Commented Sep 4, 2023 at 15:45
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    I added an answer which I hope will clarify what happened. The instructions you found were for single-boot installation, not for dual-boot.
    – harrymc
    Commented Sep 4, 2023 at 15:48

1 Answer 1

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An EFI partition is identified by its partition signature. When booting, the UEFI BIOS searches sequentially the partitions on the disk, looking for the first one that is marked as EFI. This means that only the first EFI partition on the disk is used for all the operating systems that are installed on this disk.

You have created during the installation a second EFI partition. However, the installation searched for the first EFI partition and installed in it its stub bootloader, which was the correct thing to do. If it has used your second EFI partition, the Kubuntu installation would have been ignored by the BIOS that will only look at the first one.

You may delete the second EFI partition, as it will never be used. It's too small to bother with it any further.

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  • Great, this is the thing I am looking for. Thanks for your help!
    – Becker
    Commented Sep 4, 2023 at 15:51
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    This answer contradicts other answers and articles I've seen, like this one and this one. The latter was written by the author of gdisk. In particular I doubt that the following statement is true: "If it has used your second EFI partition, the Kubuntu installation would have been ignored by the BIOS that will only look at the first one". For now the answer looks like a try to explain the observed behavior using superficial knowledge and common sense in a hope it will look plausible enough to be upvoted and accepted.
    – Kamil Maciorowski
    Commented Sep 4, 2023 at 16:07
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    @TomYan: Of course the first EFI can point anywhere at all, but the pointing boot entry still needs to be written into it. There is no reason for the installer to point to another EFI partition rather than to the operating systems loaders, or even to search for it. One may use the installer to create 10 EFI partitions, but that doesn't mean that it needs to actually use all of them.
    – harrymc
    Commented Sep 4, 2023 at 18:31
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    I also suggest to the downvoters to read Wikipedia EFI system partition and Arch Linux EFI system partition which clearly states not to create a second EFI partition.
    – harrymc
    Commented Sep 4, 2023 at 19:15
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    Sorry, I don't just read the ArchWiki. I have been with Arch for years on different UEFI implementations. I also suggest you get more hands-on experiences and/or read specs, before believing in / spreading / misinterpreting FUDs, which have always been common on wikis by nature. (But really, the biggest problem here is that you don't reason with logic. It's not even about whether you should or should not have multiple ESPs.)
    – Tom Yan
    Commented Sep 5, 2023 at 0:55

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