Dual Boot Bootloader Partition Size

I’ve been dual booting for years with Win 10 including the past 2 (on my DD) using Elementary OS. There seem to be more installers (Pop OS for example) needing a 500MB bootloader partition recently. I thought I read that as an Endeavour requirement, but I can’t find the mention. This piece though https://endeavouros.com/docs/installation/calamares-offline-installer-tips/ mentions installing boot on the shared Windows partition which would definitely not be 500MB (100 or 200 depending). So, unless you had installed Linux 1st and got a 500MB boot partition or been a mind reader when you set up Windows boot you are going to need to start over or create a second boot. I am NOT going to reinstall Windows as I have too much going on there. I will either wait for Elementary 6.0 or install something else that I can simply select the existing bootloader during install. I am loving Endeavour on my Linux only machine though and am very interested in switching. Does this installer actually need a 500MB boot partition? Thoughts?

I am on Linux only multiboot systems at the moment. But in the past, dual/multi -booting with Windows sharing its ESP with other Linux systems was never an issue.

My guess is that you will be just fine installing EnOS and sharing the existent ESP. 100 MB is enough space for harboring several bootloaders.

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Thats strange, I also run dual boot but my windows system assigned 500 MB as EFI system for the boot-loader. In the long run might be worth it, more flexibility to install the distro of your choice in case the boot-loader needs a partition with this space.

I will also check on my other computer in case it is smaller…

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Thank (to pebcak as well), and I look forward to seeing what you see. Might be a change to the Windows installer since I have ran it, or maybe it was an OEM install. I have looked at a bunch and it was never 500 from a clean Windows install. P.S. I am running EFI, and not legacy in case you were wondering.

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Ok can confirm. I have another system with two separate ssd and dual boot win and EOS.

Strangely I have two efi partitions one for win 260MB on ssd1 and one for EOS of 300 MB on ssd2, the linux bootloader used 896KiB. Was not aware that I can dual boot with two separate efi partitions but EOS setup things automatically so that it works nicely together!

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Win uses 34.30 MiB on the EFI, I suppose you are good to go!?

You know it but, make a backup…

What install method did you use on that dual drive one? I assumed “other,” but clearly you didn’t. I am sure the size wouldn’t be an issue, but I’d rather not find out it was a checked requirement as that is what happens on others that require 500.

I chose erase and install, and made sure to select the second ssd. In your case I would first create an empty partition in windows then install on that one, it will be easier to avoid a mistake. If you need more tweaking, I would also choose other, then you can add a home partition swap etc.

I am not sure but EOS seems to automatically select the right partition for the bootloader since it is available from the win install.

Good luck, hopefully things work out smoothly.

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Appreciate it. I will give it some thought.

I use 512-550 mb and I see no reason to use less for myself. Windows does only set 100 mb but i consider that too small in my opinion as this is a Microsoft recommended size for GPT for Windows. They are not looking at multiboot that some people are doing with multiple distro’s. You can use the existing efi if it already exists on Windows but i use a separate efi on my installs of linux because i usually have them on another disc. Even if they are not i still usually have the efi partition on my linux. It is recommended to use at least 512 on the Arch forum.

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That is helpful and encouraging. My existing one is 100 MB and has no issues running Windows 10 and Elementary with Grub, so hopefully it will work.

You bring up an interesting thought as well. I have been hesitant to do the Linux on a separate drive method. I currently have both Windows and Linux Core files on my 256 GB SSD, and my 1TB HDD is partitioned for both a Windows side and Linux side along with a mount on boot for the Linux side. I could put Linux completely on the HDD while still leaving a bit for Windows. Not sure how well Grub will play with two Bootloaders. Of course, I would have to fix the Windows bootloader after deleting the existing Linux partitions and then start from scratch with the dual boot including a 500MB+ bootloader for the Linux drive. Any advice before I potentially ruin my Windows install would be great.

Some outline of your setup might be useful. Please post the output of:

sudo parted -l

the current setup on this machine

4 linux systems, each with bootloader installed on own ESP. The one controlling the boot process is from EnOS Cinnamon.

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I will when I am back in Linux. I am in Windows currently and running a build that will take me a couple of hours to complete.

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There is nothing wrong with having Windows and Linux on the same drive. That’s entirely up to you. The SSD is faster than the hard drive. I’m not sure you want to reinstall Windows? Therefore I would keep them both on the SSD and have a /home partition also on Linux and then use the hard drive as you currently are as a mount point for data for both Linux & Windows. You don’t have to do anything to grub when you install Linux. OS prober should pick up the Windows installation and add it to grub. You can have an efi partition on Linux and the one on Windows. That doesn’t matter. It should find what it needs for Windows. If it doesn’t then you will need to fix the grub on Linux. This is my thought. Others may have other ideas.

Edit: You can also just use the current EFI partition from Windows if you wanted. You just have to make sure you select it and flag it as /boot/efi and /boot when you do your manual partitioning as part of the install process. I personally use a separate EFI on my other installs. I have triple boot EndeavourOS on separate drives using rEFInd and I still have EFI on each. It’s not required but that is what I do. To each his own. A little waste of space I guess.


That was my original thought except for to use the Windows bootloader to house both. I did already have /, swap, and home partitions on the Elementary install. I should just be able to select the existing ones and select format for the / and home partitions while installing Endeavour.

Exactly…as I edited above.

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Model: ATA HGST HTS721010A9 (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:

Number Start End Size File system Name Flags
1 1049kB 393GB 393GB ntfs Basic data partition msftdata
2 393GB 1000GB 607GB ext4

Model: PM951 NVMe SAMSUNG 256GB (nvme)
Disk /dev/nvme0n1: 256GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number Start End Size File system Name Flags
1 1049kB 556MB 555MB ntfs Basic data partition hidden, diag
2 556MB 661MB 105MB fat32 EFI system partition boot, esp
3 661MB 677MB 16.8MB Microsoft reserved partition msftres
4 677MB 132GB 131GB ntfs Basic data partition msftdata
5 132GB 180GB 48.0GB ext4
6 180GB 196GB 16.0GB linux-swap(v1)
7 196GB 256GB 60.3GB ext4

I figured out where the 500+ needed boot documentation was, and it looks like it is a no-go with less. It explicitly says it in the installer splash. Looking at the something else, I wasn’t going to mess with it when I looked at it. I have done it in GParted a ton of times, but this installer was a bit different. I do tend to think now that if I move it will be after reverting the system to Windows only, fixing Windows boot and installing Linux solely on the HDD with a new boot there.