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When installing Linux, there is an option to set a partition as bootable flag. Do you need to have this option turned on if you are installing Linux in UEFI mode? and if so, what partition should it be turned on? (is it / or /boot)?

I have seen this video: https://www.youtube.com/watch?v=DRhuVxaBuKU Where in 3:10 he boots Linux into a bootable USB Media via UEFI mode, and then creates the root partition and turns on bootable flag at 4:15

If it has no effect then it is safe to assume that you should not set any partition as bootable flag.

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This flag is irrelevant when an UEFI partitioning scheme is used. You only need an "EFI system partition" to be able to boot successfully.

Edit: speaking of Windows 10.

By default it sets the following two flags for the EFI system partition (as seen by parted): boot, esp. I've removed both and Windows 10 continues to boot successfully, so they are not required.

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    The boot/esp flags are normally on the ESP - efi system partition with UEFI and gpt partitioning. Grub does not use boot flag, Windows in BIOS mode requires boot flag on its Boot partition or main partition if it has the boot files. A few BIOS did require a boot flag even if only Linux and using grub, so we typically have a boot flag with BIOS even if not not used.
    – oldfred
    Nov 20, 2020 at 14:26
  • Not sure if removing flag changes ESP. Setting flag actually makes partition have very long GUID to specify type. Seelsblk -o name,fstype,label,PTTYPE,parttype,partuuid,mountpoint And en.wikipedia.org/wiki/GUID_Partition_Table for ESP partition = C12A7328-F81F-11D2-BA4B-00A0C93EC93B Also UEFI already has entry to boot by GUID/partUUID of partition which would not change. Compare partuuid with this: sudo efibootmgr -v which shows which GUID/partuuid it uses for booting.
    – oldfred
    Nov 20, 2020 at 19:16
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    Without the flags boot, esp, os-prober was unable to detect Windows 10 while configuring grub with grub-mkconfig, be aware of that.
    – Marcs
    Jul 20, 2021 at 11:20
  • When editing a GPT-partitioned disk, the boot and esp "flags" are just a design choice in the UI of the parted/gparted tools. What they actually do is determine the partition type GUID that will be assigned to the partition. If the UEFI firmware has the NVRAM boot variables intact, the firmware may or may not care about the fact that the partition indicated by the boot variable does not actually have the correct type GUID for UEFI ESP. But if the NVRAM variables should be lost (BIOS reset?), then it might be important that the ESP is readily identifiable as such.
    – telcoM
    Mar 24, 2022 at 11:38

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