linux-kernel - Re: Suspend to disk: do we HAVE to use swap?

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Message-Id: <200610312019.38368.rjw@sisk.pl>
Date:	Tue, 31 Oct 2006 20:19:37 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alistair John Strachan <s0348365@....ed.ac.uk>
Cc:	Luca Tettamanti <kronos.it@...il.com>,
	linux-kernel@...r.kernel.org,
	John Richard Moser <nigelenki@...cast.net>
Subject: Re: Suspend to disk:  do we HAVE to use swap?

On Tuesday, 31 October 2006 20:05, Alistair John Strachan wrote:
> On Tuesday 31 October 2006 17:40, Luca Tettamanti wrote:
> > Alistair John Strachan <s0348365@....ed.ac.uk> ha scritto:
> > > On Tuesday 31 October 2006 06:16, Rafael J. Wysocki wrote:
> > > [snip]
> > >
> > >> However, we already have code that allows us to use swap files for the
> > >> suspend and turning a regular file into a swap file is as easy as
> > >> running 'mkswap' and 'swapon' on it.
> > >
> > > How is this feature enabled? I don't see it in 2.6.19-rc4.
> >
> > Swap files have been supported for ages. suspend-to-swapfile is very
> > new, you need a -mm kernel and userspace suspend from CVS:
> > http://suspend.sf.net
> 
> I know, I use swap files, and not a partition. This has prevented me from 
> using suspend to disk "for ages". ;-)
> 
> Is userspace suspend REQUIRED for this feature?

No, but unfortunately one piece is still missing: You'll need to figure out
where your swap file's header is located.

However, if you apply the attached patch the kernel will tell you where it is
(after you do 'swapon' grep dmesg for 'swap' and use the value in the
'offset' field).

Please read Documentation/power/swsusp-and-swap-files.txt before you begin. 

Greetings,
Rafael


-- 
You never change things by fighting the existing reality.
		R. Buckminster Fuller

View attachment "mm-print-offset-for-swap-files.patch" of type "text/x-diff" (2290 bytes)