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I am having trouble understanding the difference between the EFI System Partition (ESP) and the linux /boot partition.

Reading online tells me that /boot partition is going to contain the boot loader i.e. GRUB2. Then, if that's the case, and if I store GRUB on the ESP, then is it same as the /boot partition ?

Or is it that GRUB2 is suppose to be stored on the ESP (something I have done before, and it worked) and the /boot partition is suppose to contain files for GRUB to find, typically files needed to be loaded before, let's say, an encrypted LVM is loaded.

What are the difference between these two ?

  • Which OS are you using? – direprobs Aug 7 '17 at 13:12
  • @direprobs Ubuntu – ng.newbie Aug 7 '17 at 17:07
  • You might be interested in Rod's books on EFI, I keep recommending those as someone whom these helped a lot during UEFI implementation in ALT Linux. :) – Michael Shigorin Aug 8 '17 at 5:42
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The EFI System Partition is the partition the EFI firmware (in ROM on the motherboard) knows of and from which the firmware can load EFI applications like boot loaders. So the ESP is the place where you put GRUB2 for the firmware to load and run. The /boot directory/partition is the place for GRUB to find files it needs, like you said. However, there is no reason the ESP and /boot can't be the same partition.

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    Unless you are running Debian, which has a policy that /boot cannot be a FAT32 file system (which the ESP must be), because FAT32 does not support symlinks. – Johan Myréen Aug 7 '17 at 13:15
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    For example on my system running Ubuntu, /boot is a directory, whereas, the ESP partition is of type fat32 and mounted on /boot/efi. – direprobs Aug 7 '17 at 13:16
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    If you wan't to do without GRUB and have the firmware boot the kernel directly, the ESP and /boot must be the same partition, or at least the kernel image must be put on the ESP. – Johan Myréen Aug 7 '17 at 13:31
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    It requires the kernel to be configured with CONFIG_EFI_STUB, which makes the kernel file an EFI binary. – Johan Myréen Aug 7 '17 at 13:50
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    Additionally, if you're multibooting with something other than Linux, it is often safer to have the ESP be a separate partition from /boot because it reduces the chances that the other OS will mess things up in /boot. – Austin Hemmelgarn Aug 7 '17 at 14:35

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