> as I'm stuck with a (non-EFI x86_64) system with encrypted root
> partition, I have to enter the passphrase twice (grub needs it for
> getting the kernel etc., systemd needs it for mounting the root
> partition). This can be quite inconvenient, especially if the passphrase
> is long and contains special characters, and grub assumes a different
> keyboard layout.
Just fill another LUKS slot with a randomly generated key file and add that
file to your initramfs (which already resides on encrypted /boot, right?). If
your distro cannot do that, you should probably fixing things there, not
adding ugly hacks to the kernel.
Check how it is implemented in Arch, for instance . I'm not sure whether
this is currently possible with openSUSE, though.