linux-kernel - Re: [RFC][PATCH -mm 2/5] swsusp: Use memory bitmaps during resume

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Message-ID: <20060809114942.GS3308@elf.ucw.cz>
Date:	Wed, 9 Aug 2006 13:49:42 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	LKML <linux-kernel@...r.kernel.org>, Linux PM <linux-pm@...l.org>
Subject: Re: [RFC][PATCH -mm 2/5] swsusp: Use memory bitmaps during resume

Hi!

> Make swsusp use memory bitmaps to store its internal information during the
> resume phase of the suspend-resume cycle.
> 
> If the pfns of saveable pages are saved during the suspend phase instead of
> the kernel virtual addresses of these pages, we can use them during the resume
> phase directly to set the corresponding bits in a memory bitmap.  Then, this
> bitmap is used to mark the page frames corresponding to the pages that were
> saveable before the suspend (aka "unsafe" page frames).
> 
> Next, we allocate as many page frames as needed to store the entire suspend
> image and make sure that there will be some extra free "safe" page frames for
> the list of PBEs constructed later.  Subsequently, the image is loaded and,
> if possible, the data loaded from it are written into their "original" page frames
> (ie. the ones they had occupied before the suspend).  The image data that
> cannot be written into their "original" page frames are loaded into "safe" page
> frames and their "original" kernel virtual addresses, as well as the addresses
> of the "safe" pages containing their copies, are stored in a list of PBEs.
> Finally, the list of PBEs is used to copy the remaining image data into their
> "original" page frames (this is done atomically, by the architecture-dependent
> parts of swsusp).
> 
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>

ACK. If we get bitmap code we may as well use it. Should wait in -mm
for a while.

> @@ -53,7 +40,7 @@ static inline void pm_restore_console(vo
>  static inline int software_suspend(void)
>  {
>  	printk("Warning: fake suspend called\n");
> -	return -EPERM;
> +	return -ENOSYS;
>  }
>  #endif /* CONFIG_PM */
>  

Heh, yes, it is right.. it is also totally unrelated and changes
userland interface ;-)))... which is probably okay here. But separate
would be nice.
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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