linux-kernel - [SUSPECTED SPAM] Re: [linux-pm] Proposal for a new algorithm for reading & writing a hibernation image.

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Message-ID: <9rpccea67yy402c975fqru8r.1275576653521@email.android.com>
Date:	Thu, 03 Jun 2010 16:50:53 +0200
From:	Pavel Machek <pavel@....cz>
To:	Nigel Cunningham <ncunningham@...a.org.au>
CC:	pm list <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	TuxOnIce-devel <tuxonice-devel@...onice.net>
Subject: [SUSPECTED SPAM] Re: [linux-pm] Proposal for a new algorithm for reading & writing a hibernation image.



"Nigel Cunningham" <ncunningham@...a.org.au> wrote:

>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.

I'm not sure it is impossible, but it certainly seems way too complex to be
practical.

2mb pages will probably present a problem, as will bat mappings on powerpc.
--
Sent from my Android phone with K-9. Please excuse my brevity.