So there is something talking about Microsoft in the EFI partition.
Of course I never try to use that Grub entry (except just now to see what it does) and in day-to-day working it does not bother me. But it could be that some onlooker would see it when I boot the system and I find it rather embarrasing that the word Windows would then be shown on my screen :shame:.
My question: is it normal to have this Grub entry after an installation that wiped Microsoft Windows from the system. And when yes: is this more or less a bug the installer?
os-prober does not care about Windows, it only looks for Windows bootloader. Delete \EFI\Microsoft directory if you no more have Windows installed. You may have copy of Windows bootloader as \EFI\Boot\bootx64.efi as well.
Do I have to remove /boot/efi/EFI/Boot/boot64.efi or even the whole /boot/efi/EFI/Boot?
Stays the question about why the installer does this.
It apparently writes there, because there is /boot/efi/EFI/opensuse (which I bet wasn’t there when I bought the system).
It seems that it does not create fresh contents for the EFI partition and that it only dares to add an opensuse directory thnking it to risky to do anything else.
Installing this system was already some time ago, thus I am not sure anymore on what I did. It is thus possible that I only removed all partitions except /dev/sda1 (EFI) and build up from there. In that case I have some understanding for the installer only adapting EFI to openSUSE.
Maybe, when I then would also had deleted /dev/sda1, the installer would have created a new one with only what is needed.
Tests for the next installation, except when anybody here has already some experience with this.
I recommend removing “bootx64.efi”. Perhaps remove everything in that directory, but do not remove the “Boot” directory.
At some future time (after there has been a grub update), you will again have a “bootx64.efi” file there. But this time, it will have been installed there by openSUSE.
That’s actually a fallback boot option, in case something goes wrong with the one in “/boot/efi/EFI/opensuse”. But your openSUSE install won’t put it there if it sees an entry there from another operating system.
Stays the question about why the installer does this.
It is part of installing grub2 booting on a UEFI system.
Installing this system was already some time ago, thus I am not sure anymore on what I did. It is thus possible that I only removed all partitions except /dev/sda1 (EFI) and build up from there.
Yes, that seems to be what you did.
Maybe, when I then would also had deleted /dev/sda1, the installer would have created a new one with only what is needed.
That would have worked, too. But what you did is fine.
You might also run (as root) the command:
efibootmgr
If it has an entry for Windows, then you can remove it. To remove, use:
efibootmgr -b NNNN -B
where the “NNNN” is replaced by the boot entry number for the Windows boot loader entry (a hexadecimal number). Any use of “efibootmgr” lists those numbers for various boot entries.