Install NixOS on UEFI hardware and MBR partition table?

gesangen · February 21, 2025, 4:58pm

Trying NixOS for the first time after using it in a VM for a while.

I’m on a uefi machine, but I’m trying to keep my home partition from a previous OS which was on an MBR partition scheme.

Using the graphical installer, I would get there error that the bootloader could not be installed, and when following instructions to install via command line, I would get the error that my efi partition isn’t on a GPT partition label.

I found some discussion over installing NixOS os UEFI + MBR combo, but none seemed to work.

Is such an installation possible, and if so how can it be done? i.e. What partitions and formats do I need, are there any configuation.nix options I must set?

I used these tutorials
https://nixos.wiki/wiki/NixOS_Installation_Guide
https://nlewo.github.io/nixos-manual-sphinx/installation/installing.xml.html
And found these posts which didn’t provide much information
https://www.reddit.com/r/linuxquestions/comments/gt7172/nixos_with_mbr_and_uefi_is_it_possible/

github.com/NixOS/nixpkgs

NixOS can’t be installed on MBR+UEFI system

opened 03:44AM - 30 May 20 UTC

closed 03:45PM - 30 May 20 UTC

volb

**Describe the bug** NixOS does not install on MBR+UEFI systems with default ins…tructions (or any I’ve found). **To Reproduce** Steps to reproduce the behavior: I have a laptop with Windows 10 and until recently it also had a Fedora dual boot with an ext4 /boot partition. I deleted Fedora and the /boot partition and nixos-install complains whether I follow the GPT/UEFI instructions or the MBR/BIOS instructions. Either it complains that I don’t have GPT (which I cannot switch to without wiping my computer) or it can’t find /boot (which I am not supposed to have according to the MBR instructions). **Expected behavior** It should not complain about a /boot partition if I do not need one. **Screenshots** If applicable, add screenshots to help explain your problem. **Additional context** **Notify maintainers**  **Metadata** Please run `nix-shell -p nix-info --run "nix-info -m"` and paste the result. Maintainer information: ```yaml # a list of nixpkgs attributes affected by the problem attribute: # a list of nixos modules affected by the problem module: ```

Any help would be much appreciated!

waffle8946 · February 21, 2025, 5:05pm

Yes, all four combinations of GPT vs MBR and EFI vs BIOS are possible, though some are more tortured than others and would require the firmware to play along.

Look into Partitioning - ArchWiki.

Also avoid nixos.wiki which is dead, I suggest using the official manual at https://nixos.org/manual/nixos/unstable/#sec-installation-manual or if you want the wiki use wiki.nixos.org (which I also suggest you edit your link to refer to).

gesangen · March 1, 2025, 3:51pm

Sorry for not returning for a while. After much documentation reading and headaches, I couldn’t get it to work, and just switched to GPT. Worked fine.