A separate boot partition or not - advantages/disadvantages?

When some folk install Manjaro, they have a separate /boot and /root partitions, instead of just one /root partition. What's the advantage of having boot on its own partition?

You can get fancy with it. If you use EFI its a must.
(well not necessarlly /boot, but /boot/efi in my case)

And that's the only thing I like on EFI, I encrypt everything else, even /boot is encrypted with LUKS.

With bios boot have to expose the /boot, well nothing really compromising in /boot but at least I feel better, not sure how this EFI thing is backdoored anyway.

EDIT: why the default installers leave 300Mb on the /boot/efi when it uses like 408K is a great mystery to me still.

For me it's just a habit, there were times where a separate boot partition was necessary for certain things to work (e.g. incompatibility with some filesystems with GRUB).
I just kept it that way although it's not necessary anymore.

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@cscs
@freed00m
Sorry:
I should have mentioned that I use an MBR (MSdos) formatted drive, not UEFI (GPT formatted) ...

Yes, I don't see the point of it on an MBR formatted drive, where I have a 100MB /boot partition (about 54MB is used up) on a Samsung netbook. Originally, it was one of Spatry’s Cup-of-Linux Beginners' Guide videos that inspired me, when I first started Manjaro, and he used a separate /boot partition on an MBR formatted drive - but I question this now ...

One use case for separate /boot partition is with fully encrypted systems (ie luks root partition).

If you don't have a separate /boot partition then the /boot directory resides within the encrypted root partition. The /boot directory contains grub config, initrd images and kernels.

$ ll /boot
total 128288
drwxr-xr-x  5 root root     4096 Apr  1 07:58 .
drwxr-xr-x 18 root root     4096 Nov 29 16:07 ..
drwxr-xr-x  3 root root     4096 Jan  1  1970 efi
drwxr-xr-x  6 root root     4096 Apr  1 08:00 grub
-rw-r--r--  1 root root 29040710 Apr  5 13:44 initramfs-4.14-x86_64-fallback.img
-rw-r--r--  1 root root 10411786 Apr  5 13:44 initramfs-4.14-x86_64.img
-rw-r--r--  1 root root 29790072 Apr  5 13:44 initramfs-4.15-x86_64-fallback.img
-rw-r--r--  1 root root 10448916 Apr  5 13:44 initramfs-4.15-x86_64.img
-rw-r--r--  1 root root 24990159 Apr  5 13:44 initramfs-4.9-x86_64-fallback.img
-rw-r--r--  1 root root  9969169 Apr  5 13:44 initramfs-4.9-x86_64.img
-rw-r--r--  1 root root  1668608 Mar 14 18:22 intel-ucode.img
-rw-r--r--  1 root root       22 Apr  1 04:41 linux414-x86_64.kver
-rw-r--r--  1 root root       22 Apr  1 03:46 linux415-x86_64.kver
-rw-r--r--  1 root root       21 Apr  1 03:29 linux49-x86_64.kver
drwxr-xr-x  2 root root     4096 Jun 26  2017 memtest86+
-rw-r--r--  1 root root  4835088 Apr  1 04:41 vmlinuz-4.14-x86_64
-rw-r--r--  1 root root  5212016 Apr  1 03:46 vmlinuz-4.15-x86_64
-rw-r--r--  1 root root  4946208 Apr  1 03:29 vmlinuz-4.9-x86_64

This means that in order for grub menu to be displayed you would have to enter your luks passphrase first, to decrypt the root partition.

Some people prefer to have the grub menu display without having to enter a passphrase, particularly with dual boot systems.

In this instance /boot is a separate non encrypted partition and you only enter the passphrase when booting the selected encrypted system.

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zstd compression of btrfs is not supported by Grub yet. That's why I have a separate boot partition, where I enabled zstd compression (which is both fast and has high compression ratio).
f2fs only recently got supported by Grub, Manjaro beging the pioneer here.

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