multiboot [Solved]

[fehlix]

And when installing any system I didn't change any parameters - everything by default (apart from choosing the partition, local settings, of course). But since I installed MS Windows first, there may have been UEFI already there

The ESP created by Windows would be ok to choose. When you run MX Boot Repair from a MX LiveUSB do choose the existing ESP on the GPT drive. (Don't get confused if it offers the ESP of the LiveUSB.) The EFI-grub loader copied onto the ESP by MX Boot repair is only about ~1-2 MB.
You might find later within UEFI Boot loader Options (a fresh entry for MX19 - on most system requiers a Fn-key to list available UEFI boot loader entries to choose from) The MX19 EFI-grub loader should be at first position.
You shall find the freshly generated EFI-grub loader on the ESP under /EFI/MX19..?/grubx64.efi.
The MX partition holding /boot/grub is burned into /EFI/MX19..?/grubx64.efi, hence you would need to regenerate/refresh the efi-grub loader to point to the valid /-partition holding the /boot/grub folder of the MX KDE installation.

[ancer]

Thank You all for help!
Huckleberry Finn, when I use "Sudo efibootmgr" I get:
BootCurrent: 0003
Timeout: 1 seconds
BootOrder: 0003,0001,0002,0000
Boot0000* ubuntu
Boot0001* MX19
Boot0002* Windows Boot Manager
Boot0003* pclinuxos

So now I have to boot from live USB (MX KDE) system and install it to the very same pendrive and choose boot location my MX partition on SSD?

[Huckleberry Finn]

(Particularly when booted to your installed MX)

Code: Select all

sudo efibootmgr -o 0001,0003,0002,0000

Reboot.

This will make MX #1, PCL. #2 ... (Later you can even delete some of them (those belonging to other removed distros etc.) again with efibootmgr ... )
__________________________________________________________________________

If after doing the above then rebooting doesn't work, then just reinstall grub as above on live session.
Just as Fehlix mentioned, one needs to not confuse the esp partition of the usb stick and the esp of the disk drive. (You need to install on the ESP on SSD )

So, you just need to select the one beginning with nvme0n1p (probably nvme0n1p1 , since we don't know your partitions, I just guess).

Install On: ESP

Location: nvme0n1p... vfat

Select /boot location: nvme0n1p3

[fehlix]

Thank You all for help!
Huckleberry Finn, when I use "Sudo efibootmgr" I get:
BootCurrent: 0003
Timeout: 1 seconds
BootOrder: 0003,0001,0002,0000
Boot0000* ubuntu
Boot0001* MX19
Boot0002* Windows Boot Manager
Boot0003* pclinuxos

So now I have to boot from live USB (MX KDE) system and install it to the very same pendrive and choose boot location my MX partition on SSD?

Assuming you have chosen the ESP on the SSD, when you installed MX KDE,
this might be easier, instead of booting from a LiveUSB:
Boot into MX KDE ( from PC LinuxOS GRUB menu)
Open terminal and copy over the efi grub-boot loader from MX KDE installation onto the ESP:

Code: Select all

sudo cp /boot/grub/x86_64-efi/core.efi /boot/efi/EFI/MX19/grubx64.efi

Next make MX19 boot entry the first one:

Code: Select all

sudo efibootmgr --verbose --bootorder 0001,0002,0003,0000

If that works and you can boot into MX Linux KDE.
Do tidy up the ESP:

Code: Select all

sudo rm  -r /boot/efi/EFI/ubuntu
sudo rm  -r /boot/efi/EFI/pclinux

and remove the not used EFI-boot loader entries:

Code: Select all

sudo efiboomgr -v -b 0003 -B
sudo efiboomgr -v -b 0000 -B

And last : copy MX KDE efi-grub loader into the fallback position:

Code: Select all

sudo cp /boot/grub/x86_64-efi/core.efi /boot/efi/EFI/Boot/bootx64.efi

HTH

[ancer]

Thank You both for Your patience with me.
I haven't removed PCLinuxOS just yet, but I am back to MX boot menu with MX booting first.
So next time I install another distro and want to restore MX boot menu I just repeat the steps You kindly provided me - I hope I don't bother You again with the same problem :-)

[Huckleberry Finn]

Glad you solved it and thank you for marking the thread :)
___________________________

P.S. On installation of any distro (including MX) just remember to have a look if there's an option / checkbox to install Grub or not. This way, you can install any distro skipping the grub installation and then on your main distro (say MX in this example) just sudo update-grub simply in a terminal , just to make the new distro to be detected and added on Grub menu ... :)