Felix Miata <[email protected]> writes: > Richmond composed on 2025-09-17 18:14 (UTC+0100): > >> Why did this all go so wrong? Why would >> Debian 13 boot without displaying Grub, even though it had a timeout of >> 5 seconds? > > Grub's upstream default changed to disabling os-prober, so 13's Grub doesn't > look > for anything else, and since the new installation had only one kernel to > offer, > there was no reason to assume other than the sole known kernel to boot. Change > /etc/default/grub to enable os-prober, and following next update of grub.cfg, > you > should find 12, 13 and openSUSE in your 13 Grub menu.
I didn't find a grub menu, and os-probe was running. It was all puzzling. I have two EFI System partitions so this must have been the cause of the problem. In the old days installation used to say "you already have grub, do you want to overwrite it?" or something like that but there was no such question. Immediately after the installation I did see a Debian 13 grub menu, but trying to fix Debian 12 caused it to vanish and never come back. So how is it that re-installing grub from the boot media rescued Debian 12, but re-installing grub from Debian 12 did not? At some point I did these commands which may have been a bad idea: sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=debian12 sudo update-grub >From Debian 12 I see: /boot/efi/EFI# ls -l total 20 drwx------ 2 root root 4096 Oct 31 2014 Boot drwx------ 2 root root 4096 Dec 28 2023 debian drwx------ 2 root root 4096 Sep 17 17:13 debian12 drwx------ 3 root root 4096 Jul 6 2014 Dell drwx------ 4 root root 4096 Oct 31 2014 Microsoft The Opensuse one is: ls -l /mnt/EFI total 4 drwxr-xr-x 2 root root 2048 Apr 7 2024 boot drwxr-xr-x 2 root root 2048 Apr 7 2024 opensuse
