[MULTI BOOT] I can't dual boot win10 and kubuntu 22.04

[Josephus]

I finally installed Kubuntu and I must say, I am glad I did...so many options I can change...I'm having some fun!

I only have 1 semi serious whine: I have since 2010 had a dual boot system: Win10 on one partition (for games) and a Linux partition (some type of Linux for everything else).

The way I have always done it is using Gparted (the stand alone Partition Manager), I make 2 partitions, one NTFS for win10 and one ext4 for Linux. Then I start the installs, usually Win10 first, and then Linux. I've done this at least 20 times with other Linux, and never had any problems (This time I also tried linux first, same results).

I'm having a very hard time setting up dual boot with Kubuntu. For some reason Kub doesn't want to play with Win10. It wants the entire disk, and the only way I can see to change it is to use the partition manager included in the installer, which I always mess up. Which means: Start Over.

It's frustrating if I want to play agame, as the only way I can do it right now, is to remove the Kub drive from the PC and plug in the win10 drive, which you can imagine gets old real fast.

I have tried installing win10 first and Kub first, but either way Kub refuses to share. I have never had this problem and honestly don't know how to fix it, so I thought I would ask here first, before I shoot the computer.

Many thanks for any ideas or suggestions.

[Qqmike]

This is how I did it several years ago, on an ASUS laptop, using modern UEFI booting.
I did use the Manual method during installation, by the way.
https://www.kubuntuforums.net/forum/...176#post597176
(I have since wiped Windows completely off! but I never had any problems dual-booting with Kubuntu.)

[Schwarzer Kater]

I understand you have two seperate drives.
Perhaps the problem why the Windows drive (or anything else) is not seen by Kubuntu anymore simply is because GRUB is set by Ubuntu to not probe for other OSes anymore.

In this case open /etc/default/grub with the Kate text editor after the installation has completed (and you have plugged in both drives) and add this line at the end:
GRUB_DISABLE_OS_PROBER=false
and save the file (you will have to enter your password to do so).

Open the Konsole terminal emulator and enter:
sudo update-grub
(You will have to enter your password again and should see something about Windows being found.)

I hope this did help.

[jlittle]

... since 2010...
Kub refuses to share.

Is it the same computer since 2010? If so, maybe it's BIOS/MBR, and Kubuntu wants to do UEFI. If you've been reinstalling Windows, have you made it UEFI?

I am confused by your problem description. The third and fourth paragraphs imply partitioning a drive and later you use the word "share", but then you say they have separate drives.

Another idea... you may have run into a change in grub, that by default disables the OS prober on new installs. (Running the OS prober has been deemed a security risk.) From the grub info:

'GRUB_DISABLE_OS_PROBER'
The 'grub-mkconfig' has a feature to use the external 'os-prober'
program to discover other operating systems installed on the same
machine and generate appropriate menu entries for them. It is
disabled by default since automatic and silent execution of
'os-prober', and creating boot entries based on that data, is a
potential attack vector. Set this option to 'false' to enable this
feature in the 'grub-mkconfig' command.

I suggest you check /etc/default/grub. I find the implicit double negative confusing, but logically you want to enable the OS prober, so you need GRUB_DISABLE_OS_PROBER=false. If you make a change to that file, run sudo update-grub to make it take effect.

[Josephus]

JLITTLE : Thanks you! No, it's not the same computer...I meant I have been dual booting since 2010 without any problems.
"
S, Kater: Thank you! You are right :

"Perhaps the problem why the Windows drive (or anything else) is not seen by Kubuntu anymore simply is because GRUB is set by Ubuntu to not probe for other OSes anymore." <-----------there lies the problem. I did not know of this change. I tried to load up Mate 22.04 = same problem.

Time to rephrase the question: One computer, I disk, 2 partitions: Partition Home = Kubuntu 22.04 Partition Forum = win10.
How do I dual boot using this configuration?

[Schwarzer Kater]

Well, as jlittle and me described: edit the file /etc/default/grub accordingly (add GRUB_DISABLE_OS_PROBER=false - e.g. with Kate) and in Konsole sudo update-grub afterwards. Simple as that.

It does not matter if you have two (or more) seperate drives with seperate installations or just one drive with multiple partitions.

Oh, and mind two things:
1. always install Windows first (optional: disable "secure boot" in BIOS/UEFI - makes things a little easier with Linux, especially if you have more than one)
2. disable "fast boot" in Windows (see: https://www.howtogeek.com/856514/how-to-disable-fast-startup-on-windows-10/ ).

[Josephus]

S. Kater: Once again I appreciate your knowledge and responses.

" 1. always install Windows first (optional: disable "secure boot" in BIOS/UEFI - makes things a little easier with Linux, especially if you have more than one)
2. disable "fast boot" in Windows (see: https://www.howtogeek.com/856514/how-to-disable-fast-startup-on-windows-10/ )."

I'm sorry, but I just don't understand what you mean. I did change the GRUB and added the statement, you suggested.

What I don't understand, is, If I must install Win10 first, (as I always do), then how can I change the GRUB, when KUB has not been installed yet?

1) I could install KUB first, change the GRUB, and then install win10.
2) And then later, after everything works, change the boot order in GRUB so KUB is my first choice (which is not crucial).
This makes sense to me...Please tell me why I should not do it that way?

Thank you for you time and patience with my ignorance.

[Schwarzer Kater]

GRUB is not a part of Windows, but of Linux (Kubuntu in your case). So of course you can only add the line in /etc/default/grub after you have installed Kubuntu too.

-> If your computer does not boot from Kubuntu but from Windows only (because there is no GRUB boot menu at all) after you have installed both on two seperate drives, the boot order setting of your drives in UEFI/BIOS (the "firmware" of your motherboard) has to be changed. Or as an quick alternative: exchange the ports the two drives are connected to.
If you use two seperate drives the installation order is not that important - just don't forget to change /etc/default/grub and run sudo update-grub in Kubuntu after both are installed so there is Windows in the (then visible) boot menu too.

-> If you wanted to install Kubuntu and Windows on the same drive (but on seperate partitions, of course) you should take my suggestion 1) into account (one drive, but two or more operating systems on it - that is what 1) was meant for).

Suggestions 2) one should always do, if there is a Windows somewhere additionally to e.g. Linux on one's computer.

There is a bit of confusion about what you have done and what you want to do: both systems on two seperate drives or both systems on the same (one) drive…
I hope this explanation brings a bit light into the dark.

[Josephus]

I know what grub is. I will try my idea and if it works, then I'm done...if it doesn't, it's time to move on and do something else.
Honestly I've had enough. No need to respond. Thank you for your help.