Multibooting with Ubuntu

[Rich Oliver]

So I like to have an Ubuntu OS as a secondary OS. I also have Windows 7 and Tumbleweed. Tumbleweed has its own UEFI Grub, so thats no problem I just have to use efibootmgr to reset the UEFI entry order from time to time after I've updated Tumbleweed. For 17.10 I installed Ubuntu before Kubuntu so Kubuntu would overwrite the grub for Ubuntu and allow me to boot through the Grub of my primary (kubuntu 17.10) OS. But a while back when I updated Ubuntu it decided to reinstall Grub and wipe out my Kubuntu GRUB. Not the end of the world but still irritating.

Was this a Meltdown related thing? Could it happen again if I install Ubuntu 18.04, before Kubuntu 18.04?

[jlittle]

I have failed to follow your post, sorry, despite wrestling with grub myself today. But perhaps I can point out one unobvious thing:

The ubuntu installer, ubiquity, that all *buntu flavours use, always wants to install grub somewhere. Supposedly this is by design, to many people will end up unbootable if the GUI let you turn off the grub install. But ubiquity can do it, you have to start it with "-b". On booting the iso, choose Try Kubuntu, then open a konsole, and

ubiquity -b

If grub would list out the available EFI boot images, it would be so simple. I don't know how to do that.

Ideally, I'd like to use the set up I had for years with Grub on it's own partition minding its own business. Can anyone give pointers on how to achieve the same result with a grub btrfs subvolume?

[oshunluvr]

Ideally, I'd like to use the set up I had for years with Grub on it's own partition minding its own business. Can anyone give pointers on how to achieve the same result with a grub btrfs subvolume?

Yes

https://www.kubuntuforums.net/showth...868#post413868

[Rich Oliver]

So Ubuntu / Kubuntu/ opensuse all mount the efi partition at /boot/efi. Tumbleweed and Opensuse install their grubs in the opensuse folder of the EFI folder hence

/boot/efi/EFI/opensuse

The problem is that both Ubuntu and Kubuntu install their uefi grub bootloaders at

/boot/efi/EFI/ubuntu

I notice I've got a neon folder from an old install, but generally I believe the ubuntu flavours all use the ubuntu folder. Is there a way to get kubuntu to use /boot/efi/EFI/kubuntu for its grub? Then there will be no problem. I can just use efibootmgr to set which grub I want to use.

[Qqmike]

Is there a way to get kubuntu to use /boot/efi/EFI/kubuntu for its grub? Then there will be no problem. I can just use efibootmgr to set which grub I want to use.

A master table of contents to EFI topics @ kubuntuforums:

UEFI, GPT, ESP, GRUB2-EFI, (dual)-booting, fixing things
https://www.kubuntuforums.net/showth...l=1#post412601

For example, you will want to look at:

UEFI for Kubuntu--simplified. And ... some dual-booting tips for Kubuntu
https://www.kubuntuforums.net/showthread.php/43221-GRUB-2-A-Guide-for-Users/page13?p=373198&viewfull=1#post373198
SECTION 6:

Section 6: All about dual-booting, 5 ways to do it, how to fix it; creating separate EFI subdirectories for your (K)Ubuntu OSs (using --no-uefi-secure-boot option).; creating and using more than one ESP, changing labels on UEFI boot entries (useful for multiple "ubuntu" entries).

It's all there, just requires a little study, like most things

[Rich Oliver]

Ah thanks, the key command was grub-install. I can just reinstall grub followed by an update-grub and everything is restored.

Normally update-grub has no effect if the grub has been wiped by another ubuntu install. But the behaviour seems to have changed. Sometime ubunutus automatically reinstall grub, but still mostly they don't.

[Qqmike]

... and you can see from the link that there are also ways to "separate" the ubuntu's in the /boot/efi/EFI subdirectories, which was one concern you had.

But, also, as you indicate, if you grub-install, that restores control to the "main" ubuntu you wish to have run the /boot/efi/EFI/ubuntu show, then the update-grub will make sure that your other ubuntu's are listed on your "main" ubuntu's grub boot menu.

Many ways to do this, right?

Glad you got it fixed.