Autoinstall - Dual boot with Windows 10

[kaarejens]

Hi,

I work for a company using Ubuntu LTS for developers, and we are using LVM and LUKS in a dual boot with Windows 10/11. Up until 22.04, this worked with manual installations, but as of 24.04, due to installer limitation, we are forced to work with autoinstall yaml configuration instead, due to our LVM setup.
I have been able to get a working LVM/LUKS configuration for pure Ubuntu machines, but when I try to do the same with Windows preinstalled, using preserve - the windows and EFI drives are preserved, but os-prober is not run (I guess since it is deactivated by default), and when activating os-prober after booting into the fresh install, no windows are detected by os-prober.

How can I make autoinstall turn on os-prober and detect an UEFI installed windows partition?

I am not able to find any information on how to configure grub/os-prober, or how to correctly preserve windows in any official documentation, nor on google, so I hope someone here are able to help me. Any help would be greatly appreciated.

My current config looks like the following:

  storage:
    config:
      - id: disk-system
        type: disk
        ptable: gpt
        path: /dev/nvme0n1
        preserve: true        

      - id: part-efi
        type: partition
        number: 1
        device: disk-system
        size: 100M
        flag: boot
        grub_device: true
        preserve: true

      - id: msr-partition
        type: partition
        number: 2
        device: disk-system
        flag: msftres
        size: 16M
        preserve: true

      - id: part1
        type: partition
        number: 3
        device: disk-system
        grub_device: false
        size: 125358137856
        preserve: true

      - id: part-boot
        type: partition
        number: 4
        device: disk-system
        size: 1G

      - id: part-encrypted
        type: partition
        number: 5
        device: disk-system
        size: -1

      - id: dm-encrypted
        type: dm_crypt
        volume: part-encrypted
        key: "REDACTED"

      - id: vg-linsys
        type: lvm_volgroup
        name: linsys
        devices:
          - dm-encrypted

      - id: lv-swap
        type: lvm_partition
        name: swap
        size: 8G
        volgroup: vg-linsys

      - id: lv-root
        type: lvm_partition
        name: root
        volgroup: vg-linsys
        size: -1

      - id: format-efi
        type: format
        volume: part-efi
        fstype: fat32

      - id: format-boot
        type: format
        volume: part-boot
        fstype: ext4

      - id: format-root
        type: format
        volume: lv-root
        fstype: ext4

      - id: format-swap
        type: format
        volume: lv-swap
        fstype: swap

      - id: mount-root
        type: mount
        device: format-root
        path: /

      - id: mount-swap
        type: mount
        device: format-swap
        path: none

      - id: mount-boot
        type: mount
        device: format-boot
        path: /boot

      - id: mount-efi
        type: mount
        device: format-efi
        path: /boot/efi

[grahammechanical]

As a double check and to eliminate at least one possible cause - what state is Windows in? Fast Start Up on?

Regards

[kaarejens]

Thank you for your quick reply!

I have not checked this setting, but I assume it is in fast boot-up, as I understand that is the default. I have basically just installed a fresh win10 PRO, made sure bitlocker was disabled, rebooted into live ubuntu 24 and used autoinstall. This has always worked flawlessly doing a manual install with the 22.04 ubuntu LTS, so I have never changed fast boot options previously, to make dual boot work. Could this affect os-probers ability to detect Windows?

I am looking for the correct way to actually activate os-prober (aside from doing a post-autoinstall sed/awk command on the 30-os-prober file, followed by update-grub or something like that) from within the autoinstall script (or a best practice for how to do this any other way combined with autoinstall), so this is run during install. But I see your point that doing this manually, also not working, would suggest something more is a miss. I just can't understand what.

I will test your fast startup tip, and see if that makes a difference, but if you or anyone else have made an autoinstall dual boot work, I would really love to see how you did it Any best practices in regard to this topic, would also be greatly appreciated!

Cheers,
Kaare

[yancek]

Having fast boot or hibernation on prevents Linux from mounting to access a windows filesystem. It is a simple process to turn off/on as explained at the Microsoft site at the link below.

https://learn.microsoft.com/en-us/tr...le-hibernation