Re: single user v multiuser boot

On Fri, 18 Feb 2005, Warner Losh wrote:

> One can get to single user mode without a fully working vm system.  One
> can get to single user mode without having process termination working
> or image rundown working.  Multiuser also requires that the various
> synchronization primitives be fully functional.  So things like
> fork/exec don't have to work completely.  Back when /sbin/init and
> /bin/sh were statically linked, getting to single user didn't even
> require mmap to work correctly. 

I think the defintions so far have been pretty developer-centric.  From a
user perspective, the benefit of single user mode is that, other than
/sbin/init, /bin/sh, and some /dev entries necessary to launch a process,
there are few dependencies to get into a maintenance mode that can be used
to partially start the system, perform recovery, etc.  I frequently use
networking, swap, etc, from single-user, but with single-user you get the
choice to say "don't depend on <x>, because it's broke".  

Robert N M Watson