The grub menu displayed as if the system knew which partition contains the bootloader. The root partition mounted by itself. Neither dmesg nor my init/process manager threw any errors. The boot partition was not mounted, neither was swap.
I did manually create an fstab from within the installed system and all is fine, so my question is purely academic. Do modern systems not need an fstab in order to know which devices and partitions to mount where?
To be clear, grub itself doesn’t mount your root partition. Grub provides the root partition device path or id to the kernel via kernel command line. Then kernel mounts the root partition early in its boot sequence with a limited set of options (typically read only).
Logically, the root partition should be mountable without fstab because otherwise it would be a chicken and egg problem :)
Usually once the userspace starts, an init script will remount the root partition with its normal options from fstab.
(It’s a bit more complicated if initramfs is involved, but the principle is the same).
Thanks! I guess I need to read up on the boot process. 😅
Good thinking :)