Dual Booting NixOS and Windows (with SecureBoot)

Updated: 21st July 2024
Author: MasterMach50

Windows
NixOS
Dual Boot
Secure Boot

Please do not “follow” this guide. Read the entirety of it and then make your own informed decisions.

I am not sponsored by anyone, I am writing this on my own accord and the links here were chosen without any bias. I am not liable for any damages.

For any corrections create an issue on the github repo of this page

My Current Setup (AKA your end result)

I am currently running Windows 11 and NixOS 24.11 on the same laptop on the same NVME drive. I am using systemd-boot as my bootloader to easily switch between my Windows and NixOS installations. Secure Boot was enabled using lanzaboote.

Preface (Do Not Skip This)

You will need to wipe your disk so first of all backup you data.

ALWAYS BACKUP YOUR DATA

For dual booting, the Windows install instructions is a bit different so do read through it.

First you will be installing Windows and then NixOS. Since NixOS does not support secureboot out of the box yet you will have to make it work by installing lanzaboote.

Some General Tips

Windows Installation

Preparing the ISO

A regular Windows ISO will do.

To flash the ISO to a USB drive I used Rufus form another Windows machine. If you are using rufus then before flashing the iso to a usb drive rufus will give you the option to disable bitlocker encryption, i recommend enabling this. If you did not get this option then continue as bitlocker can be disabled after installing Windows. (Refer After Installing Windows section)

You can enable bitlocker from Windows after installing both Windows and NixOS and installing lanzaboote.

Disabling bitlocker is important for the install process beacuse bitlocker depends on secureboot and we need to disable secureboot for installing NixOS. If secure boot is disabled and you have enabled bitlocker you won’t be able to simply boot into Windows, you will have to get your bitlocker decryption key.

Installing Windows

During Windows installation select Custom: Install Windows Only (advanced). You will be asked select which drive to install to and to setup the partitions. You will need to setup a large EFI partition (500MB to 1GB) for dualbooting as the default EFI partition size on Windows is just 100MB which is too small for sual booting. You can do this by following this guide.

https://www.ctrl.blog/entry/how-to-esp-windows-setup.html

If you are ever planning to dual boot anything with Windows please consider creating a larger EFI partition than what Windows defaults to during Windows install.

I have gone with a 1GB EFI partition on my system

After Installing Windows

If you have not disabled bitlocker from rufus or used another tool to flash the iso or did not get the disable bitlocker option in rufus then it is time to do it now. Follow this guide if you are not sure how to do it.

https://www.howtogeek.com/805225/disable-bitlocker/

Now you will have to shrink the current Windows partition to make space for NixOS. If you are not sure how to do it the follow this guide.

https://www.howtogeek.com/212/resize-a-partition-on-windows/

The guide shows you different methods to shrink / expand partitions, but you only need to shrink the partition.

You will need to shrink the partition for as much space you need because resizing partitions after installing both OSs might not be feasable.

NixOS Installation

Before Installation

⚠️ DO NOT PROCEED WITHOUT THIS

Now you will need to disable secure boot from the system’s BIOS. The process for this will be different based on your system’s manufacturer so please look it up and do the necessary.

You will have to flash the NixOS ISO to a usb drive and boot into it. I used Rufus for this also. Again booting from a usb drive will be different based on your system’s manufacturer so please look it up and do the necessary.

Installing NixOS

During installation you will be asked to which partition NixOS should be installed. Here select replace a partition. On the partition figure given below that click on the unallocated space (grey colour) that you made by shrinking the Windows partition. Continue the installation and you will have NixOS installed with systemd-boot as the bootloader.

Be careful when doing this step, do not select the wrong partition.

After Installing NixOS

You have to now go to the bios again and set the default boot option as Linux Boot Manager. Now when you boot the system you will be able to select which OS you want to boot into.

But now we have a problem, - Secure boot is not enabled. If it is enabled again then we cannot boot into NixOS using the Linux Boot Manager option anymore.

To fix this we have to setup NixOS for secure boot. For this we are going to use a project called lanzaboote.

Installing Lanzaboote

Do not follow the instructions for installing lanzaboote from the NixOS wiki as this might be out of date and definitely DO NOT select reset all secureboot keys anywhere in the bios (you will get what I mean from the lanzaboote docs).

You will have to follow the lanzaboote docs to install lanzaboote onto your NixOS system. For this simply follow the lanzaboote docs.

https://github.com/nix-community/lanzaboote/blob/master/docs/QUICK_START.md

There are two methods given in the lanzaboote docs to install secureboot, one using nix flakes and another using niv. Use the niv method if you are not using nix flakes to configure your system.

If you followed all the instructions properly you should have a system that can dual boot NixOS and Windows and has secure boot enabled.

After All is Said and Done

https://wiki.nixos.org provides some general tips for NixOS and Windows dual booters here. It also talks about things like how to make the bootloader detect Windows (In our case Windows would be automatically detected), how to use grub instead of systemd-boot as the bootloader and about dual booting using different drive configurations.

Refer to the System Time section from https://wiki.nixos.org to make sure that time on Windows remains in sync when dualbooting.

https://wiki.nixos.org/wiki/Dual_Booting_NixOS_and_Windows#System_time

General Tips

Here are some general tips for using your dual bootable system