Subject: Re: [2.6.21.1] resume doesn't run suspended kernel?
From: Nigel Cunningham <nigel@nigel.suspend2.net>
Reply-To: nigel@nigel.suspend2.net
To: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Bill Davidsen <davidsen@tmr.com>,
       Linux Kernel M/L <linux-kernel@vger.kernel.org>
In-Reply-To: <20070529124052.GH23046@elf.ucw.cz>
References: <4658B7DD.3060309@tmr.com>
	 <1180392482.4149.15.camel@nigel.suspend2.net>
	 <20070529112952.GA23046@elf.ucw.cz> <200705291403.09773.rjw@sisk.pl>
	 <20070529124052.GH23046@elf.ucw.cz>
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Date: Tue, 29 May 2007 23:13:45 +1000
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Hi.

On Tue, 2007-05-29 at 14:40 +0200, Pavel Machek wrote:
> On Tue 2007-05-29 14:03:07, Rafael J. Wysocki wrote:
> > On Tuesday, 29 May 2007 13:29, Pavel Machek wrote:
> > > Hi!
> > >=20
> > > > > Yup.  Don't we do something like this for the (ACPI-based) suspen=
d to RAM
> > > > > already?
> > > >=20
> > > > Yeah, I was thinking about this overnight too. It should be doable.=
 In
> > > > addition to what we already do, I think you'd want:
> > > >=20
> > > > - to copy the assembly to do the copying to a safe page;
> > > > - to put the location of the cpu state that was saved in the image
> > > > header so that it can be used after the data is copied back;
> > >=20
> > > ...alternatively, we can just rely on copy routine (and its data) not
> > > changing frequently.
> > >=20
> > > > - to copy the nosave data to a 'safe' page.
> > > >=20
> > > > What else?
> > >=20
> > > page directories need to be on a safe place, too.
> >=20
> > They are already.
>=20
> ...but will that place still be safe when we use other version of
> kernel?

They'll be in the image too, won't they? Failing that, the information
could be stored in the image header.

> Anyway, pagedirs are on the safe place, right? That means that we
> swsusp should no longer clash with page allocation debugging...=20

You mean DEBUG_PAGEALLOC? That can be overcome easily - I have code in
current Suspend2 that works with DEBUG_PAGEALLOC. I handle the page
fault, mapping the page and setting a flag in the fault handler to tell
the atomic copy code to unmap the page again once it has been copied.

Regards,

Nigel

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