Why is a separate /boot partition needed?

Ask Fedora
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Hi everyone,

I’m curious to know why F42 uses a separate /boot partition even when FDE isn’t used.

I’ve read the news about F43 using a 2go /boot partition by default, I’ve read users complain that the their /boot is full, so why use a separate partition when grub2 can read /boot in a btrfs partition?

I know that openSUSE Leap 16 can use FDE (LUKS + a unique btrfs partition) combined with TPM auto-unlocking (a simple box to tick during installation) with only a separate EFI partition. Why did Fedora do things differently?

I’m not an expert but I’m curious to learn the reasons.

Thank you for your time!

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I was wondering this too! I was checking on FreeBSD and only had /boot/efi and remembered I just installed F43 beta with /boot/efi: New user : installer feedback - #36 by Espionage724

But figured that can’t be where things are stored (FreeBSD only has 1.3MB usage there :stuck_out_tongue:). But if /boot can be on the same drive as /, I wonder why separate partitions is default?

I guess it gets into subvolumes and separate /home stuff as a benefit, but the simple traditional large / avoids tiny /boot issues :stuck_out_tongue:

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Because of how grub handles BTRFS and the hidden boot menu change which requires writes to /boot from grub.

Better explanation…

It also looks like some folks have manually done what you’re asking about, Safe way to move /boot to the root BTRFS partition to use snapper?

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(open)SUSE has a patch for GRUB to put grubenv into the Btrfs bootloader pad. There, GRUB is allowed to write to it. This patch is submitted upstream so Fedora should see it once the patch is merged, and Fedora rebases GRUB.

For encryption, the (open)SUSE installer has the ability to configure GRUB for encryption support, Fedora’s installer doesn’t.

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Debian 12 can also use /boot in a btrfs partition.