linux-kernel - Re: [RFC] swap image signature check upon resume

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Date:	Mon, 10 Dec 2007 05:51:04 +0100
From:	Borislav Petkov <bbpetkov@...oo.de>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Pavel Machek <pavel@...e.cz>, linux-kernel@...r.kernel.org
Subject: Re: [RFC] swap image signature check upon resume

On Sun, Dec 09, 2007 at 10:46:35PM +0100, Rafael J. Wysocki wrote:
> On Sunday, 9 of December 2007, Borislav Petkov wrote:
> > On Sun, Dec 09, 2007 at 03:27:57PM +0100, Rafael J. Wysocki wrote:
> > ...
> > 
> > > > Instead, I'd rather issue a warning that the swsusp header mismatches, say with
> > > > which kernel the machine got suspended with and then start the countdown for reboot.
> > > 
> > > What exactly would that change?  You need to reboot anyway and fsck will run on
> > > the filesystems regardless of which kernel you boot with.
> > 
> > well, you'll have the chance to reboot with the kernel the machine got suspended
> > with and then the swsusp image header _will_ match so no fsck-ing. or am i
> > missing something...
> 
> Yes, you are. :-)
> 
> With the new code (which BTW I'm assuming we are talking about) the images are
> not matched against the kernel they were created by, but against a hard-coded
> magic number (defined in suspend_64.c) playing the role of the "header protocol
> version" and against some system parameters, like the amount of RAM etc.
> Since all kernels containing the new code use the same magic number, all of
> them will match or none of them will match.

right, i was kinda wondering when actually a swsusp image won't match after looking
at check_image_kernel() but missed that arch-specific RESTORE_MAGIC bit.
Thanks for clearing that up.

-- 
Regards/Gruß,
    Boris.
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