Dual Boot Windows and RebornOS in UEFI - Updated 2021 by Azaiel

Base assumptions:

In order to keep the guide easy to follow I will make the following assumptions:

  • You have a functional copy of Windows on your desktop or laptop.
  • You have a basic understanding of how to access your computers BIOS/Boot Options
  • You have created a bootable copy of the latest RebornOS ISO.

With that in mind this guide will be broken into three separate parts:

  • Preparing Windows
  • Installing RebornOS
  • Installing rEFInd

I have included the installation of rEFInd because in many cases it's installation is simple and it just "works" with minimal additional configuration on a majority of systems.

Where possible I have included pictures.

Preparation Checklist

It's a good idea to have these items completed before attempting a dual-boot...

  • Create a backup of your current Windows System (just in case).
  • Have a bootable USB ready with RebornOS on it.
  • If you are starting from an existing installation of Windows it is recommended to defrag the drive to maximize the amount of space you can reclaim from Windows.
  • Patience. Some parts of this process seem a little scary, however I have successfully completed this process over a dozen times, and you can too!


  • I am not a professional photographer, I'm sorry for the potato quality photos.
  • I do not know all of the BIOS configurations available, if you are having difficulty selecting your boot device I would recommend checking in with our Discord group, or leave a message on our Discourse Forums. All support options can be found on our website.

Part 1: Preparing Windows

This section will focus on preparing Windows for the installation of RebornOS. It is recommended that you complete the preparation checklist above before continuing.

Step 1: Open the Windows "File Explorer" program.

Step 2: Right Click on "This PC".

Step 3: Left Click on "Manage". A window that looks like the one below should pop up.


Step 4: Double Left Click on "Disk Management" under "Storage"


Step 5: Locate the hard drive that includes your windows installation (usually labelled Drive C).

Step 6: Right Click on Drive C and select "Shrink".


Step 7: Select the amount of space to Shrink the Windows drive to, or just accept the default.


Step 8: Once you are satisfied with how much drive space you have available (I recommend at least 20GB), Left Click "Next" and insert your bootable USB containing RebornOS.

Step 9: Reboot your PC and boot from the USB containing RebornOS.

Part 2: Installing RebornOS

For this section you will be manually setting up your partitions instead of letting the installer choose for you. For the purposes of this guide we will be using a very basic partitioning structure. You are welcome to create partitions as you wish, so long as you have a separate /boot and a separate / partition.

Step 1: Boot the RebornOS Live Environment

Step 2: Ensure that you have a functioning internet connection (connect to Wifi if required).

Step 3: Start the installer.

Step 4: Proceed through the installer step-by-step until you reach the partitioning section.

Step 5: At the partitioning section Left Click on "Choose exactly where RebornOS should be installed" or the equivalent option.


Step 6: At the partitioning table, select the 'free space' that you created during the last section and click on "New". Create a partition '/boot' that is at least 120MB. I usually select Ext4 for a partition format.


Step 7: At the partitioning table select the 'free space' again, and create a second partition. This one can use the remaining space available (at least 8GB or more depending on the desktop environment you chose). Create a / partition formatted as Ext4.


Step 8: Confirm that grub 2 is to be installed on the same drive that RebornOS is installed on.

Step 9: Complete the installation as usual, reboot your PC and remove your USB stick.

Part 3: Installing rEFInd

There are a variety of options to accomplish dual booting, but in my experience rEFInd has been a relatively consistent installation experience.

Step 1: After rebooting, your PC should take you directly to your newly installed RebornOS. This is expected behavior. Go ahead and log in!

Step 2: Open a terminal window and type the following commands:

  1. sudo pacman -S shim refind
  1. yay -S mokutil

Note: If given a choice I usually don't use the git version.

Step 3: Once the above programs are installed (Shim, refind, and mokutil), you will want to switch to the root user by entering

  1. su -

and enter your password.

Step 4: Once you are in the terminal as the root user (indicated by a # instead of a $ at the end of the line with your username on it), run the following command:

  1. refind-install

If this command completes without any errors, please continue. If this command generates errors please check the following: * Your system uses UEFI/Secure Boot * Redo the installation of RebornOS and pay particular attention to your partitions. If you still get this error please reach out to us on one of the support options found on our website for assistance.

Step 5: navigate to /etc/refind.d/keys and issue the following command (still as root):

  1. mokutil -i refind.cer

Step 6: Reboot.

You should now be greeted with the rEFInd bootloader screen. This will allow you to either start in the Windows Boot Manager (for Windows), or Grub2 (for RebornOS). There are additional tweaks that you can make to the rEFInd screen, however those are outside of the scope of this guide.

Congratulations! You have successfully created a dual-boot system with Windows and RebornOS!