Ubuntu Core boot in multi-drive setup

device
1

Hello,

My setup consists of two hard drives:

  • one drive stores and boots normal Ubuntu by default
  • another drive stores Ubuntu Core

I need the following functionality: I want to boot the Ubuntu Core from Ubuntu system via grub, which is located on other hard drive.

The problem is that grub doesn’t show me any other options other than just normal Ubuntu, so I assume I need to add custom boot option to grub? Does anyone know how to configure it?

2

If you intend to use TPM based full disk encryption, you will not be able to chain boot from the grub from Ubuntu.

You can use UEFI boot entries to select what disk to start. Then that should work.

But there are also drawbacks. Shim from one installation might revoke the shim from the other. And only one OS can really provision the TPM (at least because only one can manage the lockout). In general it is not a great idea to have two full operating systems on the same machine. It might be that having both Ubuntu classic without TPM support + Ubuntu Core work fine together now. But that might change in the future.