Dual Boot Windows 11-25H2 & Kubuntu 24.04.3 LTS Noble Numbat

[JeffRedd]

Greetings! Sorry but I haven’t been here in Kubuntu Forums for a while and I miss this group. I haven’t had Kubuntu loaded in over 8 months and I miss it. I need my Linux “fix”. Yes I had some“issues” which I am reluctant to post here. I haven’t been active in this group for a while now and I’m not comfortable just bombarding you with questions. But I just wanted to put this out there in case someone could give me some advice.

I need to learn more about EFI Boot Entry entries and how to manually create an EFI boot entry. I've done some of this in Windows from the command line. I'm trying to find out how to install Kubuntu without GRUB: I've heard (from searches on the internet) that I need to run the Kubuntu installer (Ubiquity) with a specific option to prevent it from installing GRUB as the primary boot loader. I don't want to install GRUB or rEFInd or any other bootloader. And I'm not sure how to do this.

Maybe I got this all wrong but from my limited knowledge I want to install Kubuntu but without the conventional bootloaders and use EFISTUB instead. I use Windows 11 and want to install Kubuntu. I might use Windows for a week and then go back to using Kubuntu for a week. I want to choose the boot operating system want to use though UEFI and choose the boot order I want. This is want I always wanted but ended up with GRUB or rEFInd instead and I don’t like them. I already have a "Linux" partition and can even make it an Ext4 partition in Windows but I need to install Kubuntu manually.

I still have not mastered the Linux file system and feel like an idiot sometimes. I have no where to turn and I have looked all over the internet. There are almost no dual boot blogs or groups that I've been able to find on the internet. I have found one on Reddit called r/dual boot which is ok but they seem to ask more questions then they get answers. Here is my computer specs:

Lenovo ThinkPad-T16
Processor: 12th Gen Intel(R) Core(TM) i7-1270P 2.20 GHz
Installed RAM 32.0 GB
SSD Samsung MZVL21T0HCLR-00BL7 - 1 Terabyte
Graphics Card Intel(R) Iris(R) Xe Graphics 128 Megabyte

And my Lenovo ThinkPad-T16 is Linux Ubuntu certified so there has never been any issues as far as far as compatibility issues goes.

I want both operating systems to be loaded by choosing the boot order. Sometimes I will be booting into Windows and at other times I will be booting into Kubuntu. I will usually use these operating systems at week or so at time, so I will not be jumping and back forth every day. I wish I knew where to turn to. I'm usually pretty good at getting answers for computing issues but these issues have left me stumped.

Just to clear things up: I want to run the Windows 11 (25H2) and Kubuntu 24.04.3 LTS Noble Numbat on a Lenovo laptop computer that is about 1 year old.

I believe that the best choice for me is to boot with EFISTUB instead of GRUB or rEFInd or any other Linux boot loader. I've read that using EFISTUB makes the boot process faster and there is no need for an extra bootloader. I also understand that I have to choose the operating system I want to use in the UEFI setup and that is just what I want.

Now I just have to download Kubuntu 24.04 LTS live and do a manual install. I think I'm mostly there I just need a little help telling me what to do. I tried the manual install before without success. I don’t remember what the issues were at the time, but I think part of it had me stumped and I felt like I was in a little over my head.

The current situation for installing Kubuntu manually with the EFISTUB bootloader (or just doing it manually) is a bit of a challenge for me and I wish I could find some instructions somewhere.

Ideally I would really like to find a Blog or text or some kind of instructions telling me how to manually configure Kubuntu with the EFISTUB boot loader with a dual-boot Windows computer.

Thanks in advance. Sorry for the long rant. Any advice would greatly appreciated.

[Snowhog]

I haven’t been active in this group for a while now and I’m not comfortable just bombarding you with questions.

Be comfortable. We don't bite. Much. Glad to see you haven't given up on us. We're still here.

May be useful:

AI Overview

To install Kubuntu without installing GRUB, you can use the "manual partitioning" option and point the bootloader to an EFI partition on a separate drive if you are using UEFI. If you are using legacy BIOS, you can select "install grub to the partition instead of the head of the drive". In both cases, you will need to use an existing bootloader to boot the system and update it to recognize the new Kubuntu installation.

For UEFI systems

This video demonstrates how to install Kubuntu on a separate disk without a USB drive:

KMD Tech YouTube May 16, 2025

• Start the Kubuntu installation from a USB drive or other bootable media.
• When you reach the "Installation type" screen, select Something else to use manual partitioning.
• Create a new partition table or choose an existing one, and create the necessary partitions for your Kubuntu installation (root, swap, and an EFI system partition).
• Crucially, when prompted for the "Device for boot loader installation," select the EFI system partition on the new drive you are installing Kubuntu on, not the one on your existing drive.
• Complete the installation as usual. Kubuntu will be installed, but its bootloader files will be on its own EFI partition and will not overwrite the existing one.
• After installation, you'll need to use your existing bootloader to boot into Kubuntu. If your existing bootloader doesn't detect Kubuntu, you may need to manually add an entry for it.
• To boot into Kubuntu from your existing bootloader, you will need to:
  • Locate the Kubuntu EFI files on its EFI partition.
  • Copy them to the EFI partition of your main drive.
  • Update the boot menu using your existing bootloader.

For legacy BIOS systems

• Start the Kubuntu installation from a USB drive.
• When you reach the "Installation type" screen, select Something else.
• Select the correct partition for your Kubuntu installation.
• In the "Device for boot loader installation" dropdown, select the specific partition you created for Kubuntu, not the master boot record (MBR) of the entire drive.
• Complete the installation. Kubuntu will be installed, but GRUB will only be installed on the specific partition you selected.
• After installation, you'll need to use your existing bootloader to boot into Kubuntu by adding a new entry that points to the partition where Kubuntu is installed.

[jlittle]

I need to learn more about EFI Boot Entry entries and how to manually create an EFI boot entry.

In Linux the command to manipulate UEFI boot entries is efibootmgr. It's pretty clunky IMO. Also, one is at the mercy of the motherboard's implementation of UEFI; my desktop generates spurious entries, sometimes full of junk, unpredictably. You can use it booted to a live USB, installing it via APT if necessary.

I'm trying to find out how to install Kubuntu without GRUB

Warning, I've never attempted using EFIstub.
If you want to use an EFIstub set up, I suggest a read of the Arch wiki EFI boot stub.

Linux needs to be told where root is via its command line, and the initial RAM disk. grub can be set up to do this silently, and this might be the easy approach for you.

I've heard (from searches on the internet) that I need to run the Kubuntu installer (Ubiquity) with a specific option to prevent it from installing GRUB as the primary boot loader.

One runs ubiquity from a konsole with the -b switch:

sudo ubiquity -b

(With later versions of Kubuntu, calamares is the installer, and to install without a boot loader one does manual partitioning and does not specify a location for /boot/efi.)

This is want I always wanted but ended up with GRUB or rEFInd instead and I don’t like them.

Strictly IMO, your dislike is entirely rational. The way grub is set up by default is a convoluted mess IMO. Sooner or later in multiple boot set ups it always lets you down.

I want both operating systems to be loaded by choosing the boot order.

That's quite reasonable, but IMO both softwares, Windows and Linux, have tendencies to spoil that approach.

I will usually use these operating systems at week or so at time, so I will not be jumping and back forth every day.

(BTW, IMO far better than jumping back and forth, is to run both at once, with Windows in a qemu/kvm VM if you have extra monitors. When I used a work Lenovo with 2 extra monitors, and had to use Windows sometimes, I'd park Windows on one of the monitors and it was nearly seamless. I used to say Windows ran better in a VM than when I dual-booted. When a heavy windows update came down my co-workers would be twiddling their thumbs while I happily worked in Linux. I didn't run any heavy graphical software though.)

The current situation for installing Kubuntu manually with the EFISTUB bootloader (or just doing it manually) is a bit of a challenge for me and I wish I could find some instructions somewhere.

Again, the Arch wiki is a good start. Look in /boot to see the name of Linux (on my 25.10 it's vmlinuz) and the name of the initial ram disk (on my 25.10 it's initrd.img).

[JeffRedd]

Many thanks to Jlittle and to Snowhog. It seems that now I have another problem. I used to be able to run Ubuntu and all the Ubuntu flavors (including Kubuntu) on my Lenovo ThinkPadX1 computer as it was Ubuntu certified but I can not run it now. I just downloaded Kubuntu 24.04.3 (Noble Numbat) and used the latest Rufus (Rufus 4.11.2285) and wrote it as an ISO image but it wouldn't boot on either one of my Lenovo computers. So I used the latest BalenaEtcher which is (BalenaEtcher v2.1.4) and it wouldn't work on my Lenovo ThinkPad X1, which is where I'm trying to install it but it WOULD boot on my Lenovo ThinkPad T-16 without any problem. I tired to reinstall the ISO on the USB flash drive with Rufus but this time I used the DD Image mode instead of the ISO Image mode. Once again it would not boot on my Lenovo ThinkPad T-16 but it did boot on my Lenovo ThinkPad X1.

It is very apparent that no Linux Ubuntu flavor, including the Kubuntu operating system is going to install on my Lenovo ThinkPad X1 and I used to run several different versions of Kubuntu on it before. I have no idea what is happening now. I'm not sure if I should call Lenovo because my computer may not still be under warranty and they may tell me that it is only certified for Ubuntu only. Right now I'm just trying to figure this part out. Is it possible that one of the UEFI updates caused Linux to not run or crash on my system. As it is right now it will not even boot to the USB flash drive and just has a blank or black screen.

I can't tell you how much I appreciate your help. When I get this great advice, with all the details, that Snowhog and Jlittle game me I save it to text file because it's gold to me. Thanks again.

[Snowhog]

Check in the BIOS of the laptop to see if Secure Boot is enabled (if it exists). If it is enabled, disable it.

[JeffRedd]

Snowhog said:

Check in the BIOS of the laptop to see if Secure Boot is enabled (if it exists). If it is enabled, disable it.

Snowhog, I did as you said and went into my UEFI when it booted. I was able to find the secure boot and it was turned on. I turned it off and I was able to boot to the Kubuntu ISO that was on my USB flash drive. I must have forgot that I did that. Snowhog you’re an absolute genius! I never even thought about that, but I have heard before that it can cause issues but I just didn’t think about it. Thanks again.

[claydoh]

To add to this;

My little HP thin client/mini PC thing I have running my main OS (neon, based on Ubuntu 24.04), along with Kubuntu 24.04 and a dusty Windows 10 on a second drive.
For whatever reason, the two Linux grub installs (on separate drives) do not detect each other, though they find Windows just fine.

So, being lazy after a tiny bit of research and troubleshooting, I just use a hotkey during boot to bring up the hardware's EFI boot selector when I want to boot a different OS.
In my HP's case, this is F9.