Message-ID: <4C07645D.1060409@crca.org.au>
Date: Thu, 03 Jun 2010 18:14:21 +1000
From: Nigel Cunningham <ncunningham@crca.org.au>
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To: Pavel Machek <pavel@ucw.cz>
CC: pm list <linux-pm@lists.linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>,
       TuxOnIce-devel <tuxonice-devel@tuxonice.net>
Subject: Re: [linux-pm] Proposal for a new algorithm for reading & writing
 a hibernation image.
References: <4BE7475A.8030901@crca.org.au> <20100530052546.GA25287@ucw.cz>
In-Reply-To: <20100530052546.GA25287@ucw.cz>
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Hi.

On 30/05/10 15:25, Pavel Machek wrote:
> Hi!
>
>> 2. Prior to writing any of the image, also set up new 4k page tables
>> such that an attempt to make a change to any of the pages we're about to
>> write to disk will result in a page fault, giving us an opportunity to
>> flag the page as needing an atomic copy later. Once this is done, write
>> protection for the page can be disabled and the write that caused the
>> fault allowed to proceed.
>
> Tricky.
>
> page faulting code touches memory, too...

Yeah. I realise we'd need to make the pages that are used to record the 
faults be unprotected themselves. I'm imagining a bitmap for that.

Do you see any reason that it could be inherently impossible? That's 
what I really want to know before (potentially) wasting time trying it.

Regards,

Nigel
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