[SOLVED] Triple boot issues

[lcharles]

I got a new hard drive. I set up the system as UEFI only and partitioned the drive accordingly. I created a partition for Windows 10 and installed it.I set up partitions for Kubuntu 16.04 and Ubuntu 17.04. I installed them. Everything went fine. I had no problems booting, GRUB came up with all three OS's and I could boot into all three. At some point Kubuntu and Ubuntu upgraded their respective kernels. The updater ran "update-grub". I had no problems and things continued to boot just fine.

It's clear from from the boot order in the GRUB boot screen that the configuration file came from the Ubuntu installation, the one I installed last. My question is can I use "grub-install" to switch the boot loader to use the Kubuntu installation? I assume the installers ran some version of this when the installed the OS. My /boot/efi partition is sda2. So will running "grub-install /dev/sda" from Kubuntu do what I'm looking to do or do I run "grub-install /dev/sda2" ? Or is there something else I should do to get the result I'm looking for?

Just a note when I boot either of the Linux OS's a couple of lines appear during the boot. "Couldn't get size" and a bunch of numbers and letters, followed by a second line "Couldn't get uefi db list". The it boots fine. What do the lines mean? Is there something I should fix?

I have read some of the guides to UEFI here and others I've found on the web. I must say while I get a little of it, mostly it's complex and confusing. I'm glad I didn't need a lot of background to do the installs.

[Qqmike]

My /boot/efi partition is sda2. So will running "grub-install /dev/sda" from Kubuntu do what I'm looking to do or do I run "grub-install /dev/sda2" ?

Not exactly. Simply boot into your Kubuntu and issue the command:
sudo grub-install
(with no device arguments -- it will be assumed to use the ESP you set up for your Kubuntu OS, and it is already mounted at /boot/efi)

Or is there something else I should do to get the result I'm looking for?

I thought of at least 5 ways to dual boot using UEFI. Sometimes when you're bored, have nothing else to do, feel like reading ...
UEFI, GPT, ESP, GRUB2-EFI, (dual)-booting, fixing things
https://www.kubuntuforums.net/showth...-fixing-things

And you can always try the boot manager rEFInd (you'll see that in the list of how-to's in that link).

Just a note when I boot either of the Linux OS's a couple of lines appear during the boot. "Couldn't get size" and a bunch of numbers and letters, followed by a second line "Couldn't get uefi db list". The it boots fine. What do the lines mean? Is there something I should fix?

I don't know, haven't see that, but I wouldn't worry, as long as it is working -- it is probably just your UEFI firmware talking to you, or maybe GRUB, who knows.

One disclaimer here: I have no experience dual booting with Windows, which may present its own whole different game, so I hear and read. googling it usually brings up tons of things people are trying and using successfully; you seem to be successful doing it as you have things set up.

[lcharles]

Thanks, I'll keep reading.