So, in Tumbleweed what is the output of
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
Is there a line “Found Mabox Linux … on /dev/sdc4” ?
If yes, then
sudo efibootmgr -c -w -L "opensuseneu" -d /dev/sdb4 -p 6 -l "/EFI/opensuse/grubx64.efi"
would create an opensuseneu entry which can be selected in BIOS
and do not run any grub related command from mabox. Uninstall grub2 in mabox.(to prevent spoiling anything). Fingers crossed.
Based on this and tested on my system I’m not on Btrfs, but efi is not there.
Hi again – running
su grub2-mkconfig -o /boot/grub2/grub.cfg
in opensuse always finds the Mabox installation on sdc4.
As far as I know grub2 is not present in my mabox system, but I will check that.
At last one question: What do you mean with „which can be selected in BIOS”? Do you mean the boot-option-menu, that opensuse presents at start-up? Or do you mean I have to access my BIOS-settings by interrupting boot by pressing the delete-tab (at least in my case).
There is a precedence list where to boot from. In my laptop pressing F12 during boot I can select an ‘ad hoc’ line or with F2 in setup modify the Boot devices precedence with F6 up, F7 down.
Edit the opening title starting with [SOLVED] so that Boxer can go ‘zur Kasse’.
Schildkröte
Hi zolw results are as follows:
- “opensuseneu” entry was created
- but gone after restarting the machine
So no option to select “opensuseneu” in BIOS, because it isn’t there. Running efibootmgr -v right after applying your command, shows “opensuseneu” in the output. Running ebibootmgr -v after a reboot does not.
I think, it’s really time to think about reinstalling mabox. Thanks for all your help an patience 
Carsten
PS: I didn’t get the clou regards “boxer” and “kasse”…
PS2: I saw in the post you linked to, that the last expression in quotation marks is written in capital letters. I tried that, but with no success either.
Hello @avwasser,
Ooops. I thought everything is OK.
We have to study efibootmgr command
read this pls: https://www.linuxbabe.com/command-line/how-to-use-linux-efibootmgr-examples
efibootmgr -h shows help
-p | --part part Partition containing loader (defaults to 1 on partitioned devices). — It was wrong??
delete old lines as written in chapter 4
cashdesk (there is no such thing) was a flat joke, forget it.
But if you saved your data it is a good idea to reinstall mabox
Edit:
@avwasser, Try this:
sudo efibootmgr -c -d /dev/sdb -p 4 -L Mabox -l \\EFI\\Mabox\\grubx64.efi
this should create a Boot item in NVRAM pointing to the hopefully existing mabox grub.
Plan B if you have a (Ventoy) USB copy https://sourceforge.net/projects/supergrub2/ ISO there
and it explores your system for bootable systems.
Booting can be tried manually. It does not modify anything by default AFAIK (as far I know)
sudo efibootmgr -c -w -L "opensuseneu" -d /dev/sdb4 -p 6 -l "/EFI/opensuse/grubx64.efi"
Is not gonna work on your system.
Your root disk is sdb wich is the disk that should be boot nr 1 in bios and where bootloader should be.
Just read the link provided by zolw . Read carefully pkt 3. , 4. and 5.
It explains this just fine. Or fix it from a live system.
I’m out 
sudo efibootmgr -c -d /dev/sdb -p 4 -L Mabox -l \\EFI\\Mabox\\grubx64.efi
@avwasser this is my next tip. Backslashes are double or use quotes.
Hi there,
just to complete my “story”. After discussing my issue here, I chose the “edit method” during boot to get into my mabox system (#10) – for me this was the most simple and (with regards to my linux knowledge) most “harmless” solution Today I decided “out of the blue” to check, whether it is possible again to enter mabox via it’s entry in opensuse’s grub menu – and, damn, it was. I don’t know why but assume, that one of the updates (opensuse tumbleweed or mabox) within the last months healed the problem.
So: In the end, this thread is solved, hopefully.
Thanks a lot again for helping me
Carsten
PS: Is there a way to mark this thread as “solved”?