Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!auspex!guy
From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.unix.questions
Subject: Re: more on unix swap space problem
Keywords: swap fstab unix
Message-ID: <1542@auspex.auspex.com>
Date: 3 May 89 07:05:17 GMT
References: <171@larry.sal.wisc.edu>
Reply-To: guy@auspex.auspex.com (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 27

>The Question:  is the :sw: entry in fstab truly needed,

Yes.

>or is the swap info compiled into the kernel?

Yes.  (Probably.)

The problem is that in 4.xBSD's swapping code, as I remember, you have
to both

	1) tell the kernel that it is to permit swapping on a particular
	   device when you build the kernel (so, in that sense, it's
	   compiled into the kernel, although you should be able to
	   reconfigure this without kernel source)

and

	2) tell the kernel that it is to *use* a particular swap area
	   when the system comes up multi-user, which is done by putting
	   a ":sw:" entry in "fstab" and running "/etc/swapon" in one of
	   the "/etc/rc*" files ("/etc/swapon" does a "swapon" call to
	   turn swapping on for a particular partition).  The only
	   exception is the *first* swapping area, which is built into
	   the kernel and automatically turned on when you boot.

I think SunOS 4.0 has lifted restriction 1), which is an improvement.