Does the installer automatically use a newly created /boot/efi partition as the bootloader location?

[Caelarius]

Hi, I am trying to take the plunge to Linux again for my desktop. I have tried to make the switch in the past (a long time ago, in the RedHat 5 and early Suse days) but ended up back at Windows for daily desktop use. In the years between, I have been using Ubuntu server on small home servers (old pc's, zimaboard/blade, etc.) so I know my basic way around.

Because in the past I have bricked installations (I was young and carefree back then ) I want to be very sure about the bootloader. But that was a long time ago, and things have surely evolved since then. What I want to do is:

• Retain the current Windows installation and the Windows boot manager on my nvme ssd.
• Install Kubuntu 26.04 on a separate ssd (sda)
• Have the bootloader for linux be separate from the windows boot manager.
• Be able to select both the windows boot manager as well as the linux bootloader in the BIOS as boot options. I want to set the linux bootloader as the default option. From there, I can then boot either into Linux or Windows. But if I want, I should be able to go into the bios and boot Windows directly. Either as a one-time override or by setting Windows as the default boot option again.

So now the question: if during installation I create a 512 MB fat32 partition with a boot flag and mount point /boot/efi, will the Kubuntu installer automatically use that partition for the bootloader? And will it leave the Windows boot manager intact? Or do I need to tell the installer explicitly to put the bootloader there? If so, where? I did not see that option anywhere in the Kubuntu installer. But iirc I did see it in the Ubuntu installer. Hence the question, I want to be absolutely sure before attempting this.

[Schwarzer Kater]

[…]
So now the question: if during installation I create a 512 MB fat32 partition with a boot flag and mount point /boot/efi, will the Kubuntu installer automatically use that partition for the bootloader? And will it leave the Windows boot manager intact? Or do I need to tell the installer explicitly to put the bootloader there? If so, where? I did not see that option anywhere in the Kubuntu installer. But iirc I did see it in the Ubuntu installer. Hence the question, I want to be absolutely sure before attempting this.

This should work just fine. And 320 MiB should be more than enough for a /boot/efi partition (example: on one of my drives the 320 MiB EFI partition is sometimes used by up to 8 different Linux systems).
As you have to choose "manual" during the installation process anyway to achieve what you want to do, you can additionally check for every single partition what is done by the installer if this makes you feel better (I usually do this, too, despite not being necessary in most cases).

If there is an option at the bottom left where to put the boot loader, set it to the separate SSD/ sda - but I honestly can't remember anymore if it is there in the Calamares installer…

PS: Which boot loader is shown during startup depends on your UEFI settings, not on the installer.

PPS:You can check with e.g. lsblk -e7 -f in the Konsole terminal emulator if everything is where you wanted it to be after installation.

[skyfishgoo]

i would not rely on the installer to "automatically" do anything.

when you get to the part where it asks you where you want to install linux, choose the "manual" or "something else" option and you will have full visibility and control over where things go... be sure you know which device is which in the GUI that comes up.

you can either create the partitions in the installer or use pre-configured partitions you created in advance using gparted... since there is a lot going on during install, i tend to prefer creating the partitions in advance and just assign mount points in the installer, but if you are careful you can do it all at the same time.

there is a field where you specify the boot loader and you want to make sure it points to the disk you are installing on (it might default to the first disk, which is probably windows and you don't want that, it will overwrite your windows boot loader).

once you have everything installed, you can choose the linux disk as the default disk and have it always boot to grub... there you can have the windows entry (or any other linux installs) and choose what to boot that way.

but choosing from the EFI menu is also a viable alternative.

[Caelarius]

Thanks for the replies!

I opted for 512 MB for the efi partition as that was suggested in multiple locations, but good to know that amount of space is not needed.

I also had a look again at both the Kubuntu and Ubuntu installers. And indeed, the Ubuntu one does explicitly ask where it should put the bootloader as seen in the bottom left corner here:


However, I could not find the same option in the Kubuntu installer. It does ask me what storage device to create the partitions in, but not where the bootloader should be put.




In the end, I do get an overview which does seem to be correct w.r.t. all the partitions and their location. But googling this situation gives conflicting results. Some say it should work like this, others say that the installer will simply look for the first available efi partition. Which in my case should be on the nvme drive.



I'm going to do some additional digging. But if anybody has experience with this situation I'll be happy to learn what the installer actually does!

[skyfishgoo]

iirc the boot device location was a separate text window centered above the list of partitions in GUI that comes up when you choose the manual install method.... i had a drop down list of all the disks attached, and i recall changing it from sda to sdb because sda was where my windows install was located at the time.

[Caelarius]

I think that is the storage device dropdown list. I took the 24.04 installer to see if the bootloader location could be selected there, but it was the same.

But when doing so I encountered something interesting: when you go to a manual installation and only allocate an ext4/btrfs partition (so no efi partition), you get a warning window. The warning states that there needs to be a fat32 partition with a boot flag mounted at /boot/efi. So it seems that the installer does not consider the windows boot manager when you go for manual partitions and only automatically selects that when you go for an alongside installation.

[Schwarzer Kater]

Just do it - no partition (like the EFI one with the Windows boot loader) will be erased/overwritten. Only if you tell the Calamares installer to do so.

If the /boot/efi should point to the "wrong" partition you can change this manually afterwards. Feel free to ask if this is the case, but I personally will be near an Internet connection only in about 4-5 days again…

[Caelarius]

Yep, will take the plunge later today or tomorrow depending on available time. Thanks for the replies all.

[barfly]

Caelarius You are on the right track.
I nowadays always have an efi partition of at least 600gb to be on the safe side, but I often have 5 or 6 o/s's to choose from at any one time.
The defaults for Kubuntu are to install the bootloader into the existing efi partition, wherever that may reside on your drives. But it will ask you!

The other thing that confuses people is after creating partitions, the drop-down list of drives at the top of the screen reverts back to the first drive listed by the bios, NOT the one you have just selected. That is where most people come unstuck.

So for each partition you have to select the correct drive from the drop-down box all over again. This needs to be fixed in my opinion, when you are in the middle of an operation, it is an unexpected and contra-intuitive procedure.

[Caelarius]

Well, typing this from within Kubuntu, so that went well. Hello, world!

As expected, the installer played nice and left the windows boot manager alone. barfly It did not ask me for confirmation, but I guess that is due to the fact that I created a new boot partition and it was not going to touch the windows one.

=> So outcome: yes, the Kubuntu installer will use a newly created /boot/efi partition if you create it manually. It does not ask where to put the bootloader.