Recommended /boot partition size

I decided to give it a try and move /boot to a separate partition, to be able to install systemd-boot on SB:

The question arises what size it should be?

In my installation, it’s quite beefy already:

$ sudo du -hx /boot/
7,0M	/boot/grub2/themes/system
7,0M	/boot/grub2/themes
7,0M	/boot/grub2
80M	/boot/ostree/fedora-0bf7d3b888cc3006386933f1197ed20834a1e0863f0b4193e5043dfd65c5ba5c
80M	/boot/ostree/fedora-7a0695c96798fb421b68c0b3b8e98829c0cbbce58b9973408d8695bc5478648b
81M	/boot/ostree/fedora-779ba490b1b8afc8b0d97228009affa52b66360119aefb616ea4a6865834b963
139M	/boot/ostree/fedora-8c2944a11d81caf7cd1c4e27986009d08e9cb3a08af55e20987c5d6aab2bfbbb
143M	/boot/ostree/fedora-2cfd35de54fdb60eacf2eb82d54fe9f45bfe0fa642209e976de641600fe76b6c
143M	/boot/ostree/fedora-ea8b426ad6313285f12f6c60a89c116bfffe12e5a9d4cc2cf7e31f74ed8edfd8
663M	/boot/ostree
24K	/boot/loader.1/entries
40K	/boot/loader.1
733M	/boot/

Most of it is spent on /boot/ostree and I didn’t find any docs what is it.

So I wonder what is it’s grow estimate?

The spec for systemd-boot appears to suggest 1GiB (or larger).

Excerpted from The Boot Loader Specification:

  • Otherwise, if on GPT and an ESP is found and it is large enough (let’s say at least 1G) it should be used as $BOOT and used as primary location to place boot loader menu resources in.

That’s about ESP but my question is about additional partition for /boot.
It’s needed for SB to be able to install systemd-boot, see the link above.

If you have both /efi and /boot, then it doesn’t really say how big to make /boot. It does say that the only reason you should create two separate partitions is if a ESP already exists and is not “large enough” (~1G). The implication would appear to be that if your existing ESP isn’t big enough, you should make a /boot that is bigger (at least 1G).

If your ESP is large enough, you are supposed to mount it at /boot.

Edit: Another excerpt

It is recommended to mount $BOOT (either XBOOTLDR or the ESP) to /boot/. [Only] If both XBOOTLDR and the ESP are present, the ESP should be mounted to /efi/.

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I’m not, as SB breaks that spec, unfortunately.

So asking about /boot size I mean SB case, specifically.
Let’s please not deviate from that.

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Hmm, it looks like the /boot/ostree/ directory contains kernels/initramfs’s only:

$ ll -R /boot/ostree/
total 0
drwxr-xr-x. 1 root root 204 ноя  6  2020 fedora-0bf7d3b888cc3006386933f1197ed20834a1e0863f0b4193e5043dfd65c5ba5c
drwxr-xr-x. 1 root root 228 мар  8 22:54 fedora-2cfd35de54fdb60eacf2eb82d54fe9f45bfe0fa642209e976de641600fe76b6c
drwxr-xr-x. 1 root root 204 ноя 29  2020 fedora-779ba490b1b8afc8b0d97228009affa52b66360119aefb616ea4a6865834b963
drwxr-xr-x. 1 root root 204 ноя  8  2020 fedora-7a0695c96798fb421b68c0b3b8e98829c0cbbce58b9973408d8695bc5478648b
drwxr-xr-x. 1 root root 198 мар  8 16:18 fedora-8c2944a11d81caf7cd1c4e27986009d08e9cb3a08af55e20987c5d6aab2bfbbb
drwxr-xr-x. 1 root root 228 мар  9 21:29 fedora-ea8b426ad6313285f12f6c60a89c116bfffe12e5a9d4cc2cf7e31f74ed8edfd8

total 81724
-rw-r--r--. 1 root root 71976530 ноя  6  2020 initramfs-5.8.17-300.fc33.x86_64.img
-rwxr-xr-x. 1 root root 11702832 ноя  6  2020 vmlinuz-5.8.17-300.fc33.x86_64

total 145504
-rw-r--r--. 1 root root 134070195 мар  8 22:54 initramfs-6.8.0-0.rc6.49.fc40.x86_64.img
-rwxr-xr-x. 1 root root  14925640 мар  8 22:54 vmlinuz-6.8.0-0.rc6.49.fc40.x86_64

total 82916
-rw-r--r--. 1 root root 74736469 ноя 29  2020 initramfs-5.9.10-200.fc33.x86_64.img
-rwxr-xr-x. 1 root root 10165200 ноя 29  2020 vmlinuz-5.9.10-200.fc33.x86_64

total 81740
-rw-r--r--. 1 root root 71985400 ноя  8  2020 initramfs-5.8.18-300.fc33.x86_64.img
-rwxr-xr-x. 1 root root 11710480 ноя  8  2020 vmlinuz-5.8.18-300.fc33.x86_64

total 141460
-rw-r--r--. 1 root root 130060015 мар  8 16:18 initramfs-6.7.7-200.fc39.x86_64.img
-rwxr-xr-x. 1 root root  14794568 мар  8 16:18 vmlinuz-6.7.7-200.fc39.x86_64

total 145504
-rw-r--r--. 1 root root 134070183 мар  9 21:29 initramfs-6.8.0-0.rc6.49.fc40.x86_64.img
-rwxr-xr-x. 1 root root  14925640 мар  9 21:29 vmlinuz-6.8.0-0.rc6.49.fc40.x86_64

That gives me a clue, for sure.

Better we would have that somewhat documented maybe - it’s not as obvious before you look into it…