Subject: Re: Swsusp, resume and kernel versions
From: Nigel Cunningham <ncunningham@cyclades.com>
Reply-To: ncunningham@cyclades.com
To: Dmitry Torokhov <dtor_core@ameritech.net>
Cc: Pavel Machek <pavel@ucw.cz>, LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <200502170038.30033.dtor_core@ameritech.net>
References: <200502162346.26143.dtor_core@ameritech.net>
	 <1108617332.4471.33.camel@desktop.cunningham.myip.net.au>
	 <200502170038.30033.dtor_core@ameritech.net>
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Message-Id: <1108627778.4471.54.camel@desktop.cunningham.myip.net.au>
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Date: Thu, 17 Feb 2005 19:09:38 +1100
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Hi.

On Thu, 2005-02-17 at 16:38, Dmitry Torokhov wrote:
> On Thursday 17 February 2005 00:15, Nigel Cunningham wrote:
> > On Thu, 2005-02-17 at 15:46, Dmitry Torokhov wrote:
> > > But I think there is one pretty severe issue present - even if swsusp
> > > is not enabled kernel should check if there is an image in swap and
> > > erase it. Today I has somewhat unpleasant experience - after suspending
> > > I accidentially loaded a vendor kernel. I was in hurry and decided that
> > > resume just failed for some reason so I did couple of things and left
> > > the box running. In the evening I realized that I am running vendor kernel
> > > and decided to reboot into my devel. version. What I did not expect is for
> > > the kernel to find a valid suspend image and restore it. As you might
> > > imagine messed up my disk somewhat.
> > > 
> > > Any chance this can be done?
> > 
> > One of my suspend2 users had the same thing yesterday. Unfortunately
> > there's no easy way for us to detect that another kernel has been
> > booted.
> 
> What do you mean? I thought it already compares signatures of the booting
> kernel and suspend image. Just wipe it out if it does not match, or, even
> better, just stop if signature does not match unless one boots with
> "nosuspend". This way even if I start booting wrong image I have a chance
> to select right one and avoid fsck.

That would work if the alternate kernel is suspend-enabled. Suspend2
handles that case nicely and I'm sure swsusp will handle it as well
(although exactly what it does, I'm not sure. It used to panic IIRC).

If the mistakenly booted kernel isn't suspend enabled, however, you need
a more generic method of removing the image, such as mkswapping the
storage device. This is what I was speaking of.

Regards,

Nigel
-- 
Nigel Cunningham
Software Engineer, Canberra, Australia
http://www.cyclades.com

Ph: +61 (2) 6292 8028      Mob: +61 (417) 100 574

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