Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!mcvax!ukc!dcl-cs!aber-cs!pcg
From: pcg@aber-cs.UUCP (Piercarlo Grandi)
Newsgroups: comp.unix.microport
Subject: Re: swap
Summary: /dev/swap is used by user level programs; kernel only sees swapdev.
Keywords: /dev/swap
Message-ID: <1053@aber-cs.UUCP>
Date: 6 Jul 89 13:11:09 GMT
Reply-To: pcg@cs.aber.ac.uk (Piercarlo Grandi)
Organization: Dept of CS, UCW Aberystwyth
	(Disclaimer: my statements are purely personal)
Lines: 25

In article <368@trevan.UUCP> trevor@trevan.UUCP (trevor) writes:
    
    	The distribution Microport V/AT has a swap device witha major
    number of 1 and minor of 198. This is infact the mem device.

The kernel on the floppy uses a ramdisk for swapping so that the bootable
floppy can be read only. You absolutely don't want a hard disk rooted system
to continue swapping to the ramdisk. Indeed you may want to remove the
ramdisk from the hard disk kernel configuration (in favour of larger buffer
chaches).

    I suspect that it is redundant as the swap devices are also contained in
    the dsk and rdsk directories.

The kernel only obeys the "swapdev" definition given when it is built; it
completely ignores the /dev*swap device files. The /dev*swap device files are
used by "ps" (mainly) to read the u-area/stack of swapped out processes. It
is the system administrator's responsibility that the /dev/*swap devices map
onto the same partition indicated in the "swapdev" variable definition; if
they are not, "ps" (and some other commands) will just report incorrect
things.
-- 
Piercarlo "Peter" Grandi           | ARPA: pcg%cs.aber.ac.uk@nsfnet-relay.ac.uk
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcvax!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk