Dual Booting Between COS2 and Win11?

[LeoNigro]

Hi Everyone,

At the moment I haven't been able to get dual booting working through the Commodore Menu.
COS1 was able to during the Windows 7 era.
UEFI appears to have thrown a spanner in the works.

I've seen people dual boot with Win11 and Debian so it should work, but even following the steps I've still not been able to get it working.
I've been pulling my hair out for several days with this one.

I've been trying it with Win10(which is still 100% app compatible), just in case Win11 is a bit more belligerent about being the sole OS on your computer. And then, see if it retains the bootloader on upgrading from Win10 to Win11. But I gather there is no difference.

However....
I have been able to switch between the two installed OSes merely by changing the boot order in BIOS.
Sometimes just switching a parameter between UEFI and Legacy mode will work.
Sometimes you just need to disable UEFI altogether.
If finding my BIOS a bit tricksy, in that you need to save a config, save it and reboot before the right options are available.

Note: The script from the COS2 Live USB Installer is hard coded to restore GRUB if COS is the first OS installed. Otherwise the drive partition it is writing to is wrong. Nonetheless, even with the correction(or what I think is a correction) it will not perform its intended function with Win11.

If anyone has figured out how to dual boot between Commodore OS 2.0 and Windows 11 please let us know.

A dual boot option would be a nice purchasing configuration for the C64x.

Okay, off to try the Ubuntu installer and see if I can reverse engineer or get a hint as to how they perform the "Install alongside Windows" option.
Hmmmm... Triple boot anybody? Maybe I'll install the Ubuntu Mate edition, so we're comparing apples with apples to debug hardware issues.

Cheers,
Leo

[Plynx]

My install, despite having the previously mentioned NVidia driver problems, installed with dual booting just fine. Not sure if it's what you are talking about, but when I boot I get a Commodore OS selector with many options, one of which is Windows 10. I am using UEFI. Are you saying an upgrade to Windows 11 would destroy the dual boot?

[LeoNigro]

No, they likely work the same.
I'm just a little shocked it worked for you and not for me.
I guess I will have to try again now to be sure.
If I get it working with Win10 I'll perform an upgrade to 11 to check.
I wonder if the Windows edition makes a difference.
Like was it Home, or Professional...or whatever other option. I was installing Pro.
Did you do the Windows install via USB?
Also, had you installed a different Linux prior (which may have set the Grub partition properly)?

Thanks for letting me know.

[Plynx]

I had Windows 10 Pro 22H2 installed on an NTFS 2TB SSD. I don’t recall if I installed it from an USB but it was a fresh install, so it must have been. I shrank my C: partition by 250GB to prepare for the install (from Windows Disk Management). I imaged the CommodoreOS 2.0 iso I downloaded from the torrent to a USB drive with Rufus 4.5. This did not boot properly, so I had to change Rufus to add a persistent partition onto the USB, and then it worked. When I installed CommodoreOS 2.0, I looked carefully through all the options. I formatted the unallocated 250GB to ext4 using GPART. That was the partition I selected for the install. The installer picked the GRUB partition correctly and it installed properly such that now I see the Commodore OS loader every time I boot up, giving me 10 seconds to pick another boot option if I want, including Windows (though I have to scroll down to get to it, and that wasn’t obvious at first). Since then I reskinned GRUB from CommodoreOS to show more options at once.

If you need more information, I had a detailed conversation with an AI assistant while I did every step of the install, asking it about every menu option to make sure I wasn’t making any mistakes, and so I have a detailed log of every step I took along the way if you need it.

[LeoNigro]

Well, that sounds easy......too easy.
I think I pretty much did all that. But I'll give it yet another go.
Please post all the info you here if you can.
If we can lock down the process we can include this as a pre-installed option for C64x purchasers.

When you say "giving me 10 seconds to pick another boot option if I want, including Windows (though I have to scroll down to get to it, and that wasn’t obvious at first)"
What do you mean you have to scroll down to get it? Do you mean pressing the cursor keys, or is there something else going on?
And when you say you had to reskin grub what does that mean? Did you not get the regular skinned C64 OS Selector theme by default?

[Plynx]

Yes, I got a themed C64 selector with very large type, only showing three options (all Linux), with no indication that there were more options below if you kept pressing down arrow. One of these “hidden” options was Windows. I changed it to one at a higher resolution using the GRUB themes in CommodoreOS; it also says CommodoreOS, but the font is smaller and it fits all the options so I can see them all at once.

[LeoNigro]

It must be dependent on motherboard, because try as I might, there is no Windows entry for me.
I install Commodore OS
and then I install Windows 11 Home. (Wow, that tries to suck you in to its ecosystem during the installer)
If you have done the same in the same order, I wonder if you could kindly dm me(or post) your grub.cfg file. IIRC it's under /boot.
Also, could you possibly screenshot and post your GParted drive allocation?
I think the next thing I'll try, is to see if Ubuntu can do it, and perhaps it will give me some hints.

[Ixel]

I don't know if this is much help:
The ASRock bios gives you the option to select the boot device by pressing F11 during boot. Would be cool if other motherboards did the same.
Since installing Grub properly is quite a chore, I simply installed a second SSD and Linux Mint and COS are on separate hard drives. Handy if there's a problem with one operating system.

Fun fact: You keep the stylish design of the COS grub, which just looks great. It would be a pity if that was no longer there.

[tcr666@gmx.at]

Hi folks,
I actually found 2 solutions to fix this problem:

First one is with the grub bootloader in COS:


Second one is with the grub2win bootloader in Win 11:


The second solution has the advantage that you can give the resolution with to COS, so you don't need to update the kernel.

I'll write a HowTo the next days, when I have more time.

Greetings TCR

[LeoNigro]

I'll have to try this out. Thanks.
I wonder if there is something in the windows C:\grub2\grub.cfg that can be applied in our regular grub to make that work, without the need to install grub2win within Windows.