>If a user puts init=/whatever on the command line and /whatever can't be run, then the kernel will try a few default options before giving up. If init=/whatever came from a bootloader prompt, then this probably makes sense. On the other hand, if it comes from a script (e.g. a tool like virtme or perhaps a future kselftest script), then the fallbacks are likely to exist, but they'll do the wrong thing. For example, they might unexpectedly invoke systemd.