This one has been inspired by these guys:

  http://www.informatimago.com/linux/emacs-on-user-mode-linux.html
  https://raymii.org/s/blog/Vim_as_PID_1_Boot_to_Vim.html

It's aimed at building images running their main userspace
piece instead of ramdisk's init, that means PID=1, UID=0.

Mostly fun of course but it suddenly became interesting with
kernel IP autoconfiguration and e.g. elinks running this way
(NB: requires patched make-initrd 0.8.8 at the moment to get
resolver configured).

And startup times are way better than sysvinit and systemd combined!