Linux – How to know which partition is EFI system partition

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I want to install ArchLinux from working dual-boot system. There's one step where I got stuck:

# Mount the EFI System partition with: sh-4.3# mount /dev/sdaX /mnt/boot/efi

I ran fdisk -l command and got its output. How can I know which of this partitions is exactly the EFI one? Is it the one with only 100mb storage?

Best Answer

None of them. Either you don't have an EFI system, or Windows wasn't installed in EFI mode.

If you had an EFI system partition, it would always have the ef type code instead of the usual 07 or 82, and lsblk -f would show it as having a "vfat" filesystem.

Also, since Windows is rather picky about it, the disk would have a GPT disklabel (yours shows "dos" which means MBR), and fdisk wouldn't even show the type ids.

That first 100 MB partition is a "Microsoft System Reserved Partition"; while similar in purpose (even meant to mirror EFI layout), it is completely specific to the Windows boot process.

No, a partition is not one and the same as a file; and Wikipedia is misleading you.

That second paragraph is wrong on pretty much all points. EFI does not require any such things, and never relies upon a boot sector. If you want the gen on this, I suggest reading the actual EFI specification. It's fairly clear on what the \EFI\BOOT\BOOTxxx.EFI files are all about. They are the fallback default if nothing is configured in the Boot Manager. Normally, however, something will be configured in the Boot Manager.

EFI does not require a special partition table, it being capable of using both the old PC/AT (a.k.a. MBR or MS-DOS) partitioning scheme and the new EFI partitioning scheme. Nor are EFI boot applications specially located. Their locations are stored as paths in individual boot options. In theory, they don't even have to be on the EFI System Partition. They could in theory be on any volume whose filesystem format the firmware understands. In practice, the ESP is both the expected place that users will look at first and is guaranteed to exist by the platform and be locatable by EFI programs.

Jonathan de Boyne Pollard (2006,2010,2011). What "boot" and "system" volumes are. Frequently Given Answers.
Jonathan de Boyne Pollard (2011). How operating systems determine the location of the system volume when bootstrapped. Frequently Given Answers.
Jonathan de Boyne Pollard (2006,2011). The EFI boot process. Frequently Given Answers.
Jonathan de Boyne Pollard (2011). The PC/AT boot process. Frequently Given Answers.

Linux – How to manually delete the Ubuntu partition

When in doubt, leave it alone. To remove Linux, delete the partitions sda6 (Linux) and sda7 (Linux swap). Do not touch the others. While you're at it, make sure that the Windows partition (sda3) is marked as bootable.

This will not give any space back to Windows. If you want Windows to expand, you'll have to do it with Windows tools.

If your system is currently configured with dual boot, it's probably using a Linux bootloader. If you remove Linux, your system will become unbootable. You can try restoring the Windows boot sector by installing the mbr package and running install-mbr:

install-mbr /dev/sda

I don't guarantee that this will work. Your best bet is really to use a Windows installation CD.

Best Answer

Related Solutions

Boot – Relationship Between EFI System Partition and UEFI *.efi Files

No, a partition is not one and the same as a file; and Wikipedia is misleading you.

Further reading

Linux – How to manually delete the Ubuntu partition

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