I Dont Understand

[TNKEG]

Hello,
I recently found Kubuntu and tried it on a flash drive. It is a very well thought out and polished distro , I enjoy it immensely. I decided that it was good enough to stop using it on flash drives, as their read and write speeds slow the operating system, and install it on my secondary hard drive with several other distro's.
When I installed it I created three partitions, EFI Boot, root and home. I already had a swap file.I told the installer to put grub on the EFI ESP boot partition I created on my secondary hard drive.I sat and watched it install, watched it put up a notification that it was installing Grub to my EFI partion on /sdb and rebooted.I wanted to keep all my Grub boots on /sdb and leave my first hard drive /sda untouched.The other distros, I have, installed just as I expected.After I rebooted I noticed that Grub has attached itself to my Windows EFI boot loader on my primary hard drive /sda.
Does anyone have any idea what I did wrong? I installed it just like I did Linux Mint and it is fine so I know I can put Grub on my secondary hard drive.I tried using a Windows program "Easy UEFI" to correct the boot path to no avail.It is firmly attached to Windows EFI partition and the links to my /sdb EFI partition boot path are broken.

[Qqmike]

Answer:

You have set up two ESPs (EFI System Partitions, what you are calling the EFI ESP boot partition), say they are sda1 (being used for Windows) and sdb1 (that you will use for you Linux dual-boot OSs). For Kubuntu, you wish to use sdb1 as your ESP (where the Kubuntu GRUB2-EFI boot files will go for Kubuntu). Ok, then ...
Before you install Kubuntu, hide the sda1 ESP. Make sure sdb1 is created and ready (FAT32). Then install Kubuntu and its GRUB will see your sdb1 and use it. After re-booting and testing Kubuntu, turn on the ESP sda1 (so your Windows will boot).

How to hide the sda1 ESP?
I don't use Windows and so can not offer a solution from its side. However, in Linux, like your Mint, or a live Kubuntu DVD, or a live GParted CD/USB (a very good partition editor most of us here use), you can see a "boot" flag set on sda1. If you are using the command line, you can see the ESP marked as type EF00. I always simply go by the boot flag set using GParted (or the KDE partition editor from a live Kubunt DVD). My point here is simply this: Turn off that boot flag set on sda1. In Gparted Live CD/USB, you simply do this by, well, by turning it off, by simply removing the boot flag on sda1.

Gparted (a super-handy tool)
http://gparted.org/livecd.php

Obviously, after you install Kubuntu, re-boot to test it; then reset the boot flag on sda1 so your Windows will also boot.

Useful fact
If you are booted into Kubuntu (or Mint, for example). Open Konsole (a terminal), and issue the command
df /boot/efi
It will show you the device (sda1, sdb1, whatever) mounted at /boot/efi so you can confirm the ESP is correct.
In your case, your Kubuntu will see sdb1 as your ESP, mounted at /boot/efi (as seen from within your Kubuntu).

Comment
In my experience, Mint exhibited the same problem behavior as Kubuntu in this regard. As do other Linux OSs. Many OSs will by default look for the ESP at sda1. However, your experience in this regard seems different. Par for the course with the UEFI business -- things may or may not work, and then consistently or not, so it seems at times.

Summary
So if you ever wish to use "another" ESP, simply turn off all your other ESPs while you are doing your work; then afterwards, turn them all back on.

My how-to:
UEFI Simplified, A Quicker Version [for Kubuntu]
https://www.kubuntuforums.net/showth...l=1#post379977

[Qqmike]

btw, TNKEG, welcome to Kubuntu and to the forums here. You'll find this a friendly place. I switched from Windows to Kubuntu in 2006, have stayed with Kubuntu, and have never looked back. Like many of us here, I have also tried many other distros. Mint seems good. But I continue to use Kubuntu as my main OS and only experiment booting the others (for booting practice, actually). (Many people here dual boot Kubuntu with Windows and other distros.)

[TNKEG]

Qqmike,
Thank you for your reply.A straight, to the point, simple fix.I see exactly what you are saying.I can boot into an installed distro, like Kubuntu, use Gparted to mark Windows boot EFI flag to hidden . Do my installing and then unhide it afterward.
I think my problem was that I am very new to Linux and partitioning.Being new, I created a separate EFI ESP boot partition for each of the distros I have on my secondary hard drive and the installer got confused and went to the default /sda partition.I realize now that I only needed the one EFI partition on /sdb for all the distros I have.
I'm not sure how or if this forum marks things as "solved" but I consider your answer the solution.Thanks Again..

[Qqmike]

Above the line of your Post #1, on the right, Thread Tools --> Mark as Solved.

You're welcome, glad it makes sense. As you know, you can, in fact, use just one ESP (your sda1) for all your OSs on all your disks. I see your objective, though, to use one ESP for Windows and use separate ESP(s) for other OSs.