linux-kernel - Re: 2.6.18-rc4 (and earlier): CMOS clock corruption during suspend to disk on i386

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Message-ID: <20060810001232.GB4249@ucw.cz>
Date:	Thu, 10 Aug 2006 00:12:33 +0000
From:	Pavel Machek <pavel@...e.cz>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Andrew Morton <akpm@...l.org>, LKML <linux-kernel@...r.kernel.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>
Subject: Re: 2.6.18-rc4 (and earlier): CMOS clock corruption during suspend to disk on i386

Hi!

> > > > > It looks like the CMOS clock gets corrupted during the suspend to disk
> > > > > on i386.  I've observed this on 2 different boxes.  Moreover, one of them is
> > > > > AMD64-based and the x86_64 kernel doesn't have this problem on it.
> > > > > 
> > > > > Also, I've done some tests that indicate the corruption doesn't occur before
> > > > > saving the suspend image.  It rather happens when the box is powered off
> > > > > or rebooted (tested both cases).
> > > > > 
> > > > > Unfortunately, I have no more time to debug it further right now.
> > > > 
> > > > Do you have Linus' "please corrupt my cmos for debuggin" hack enabled?
> > > 
> > > Well, I know nothing about that. ;-)
> > 
> > CONFIG_PM_TRACE=y will scrog your CMOS clock each time you suspend.
> 
> Oh dear.  Of course it's set in my .config.  Thanks a lot for this hint. :-)
> 
> BTW, it's a dangerous setting, because some drivers get mad if the time after
> the resume appears to be earlier than the time before the suspend.  Also the
> timer .suspend/.resume routines aren't prepared for that.

Its config option should just go away. People comfortable using *that*
should just edit some header file. Rafael, could you do patch doing
something like that?

-- 
Thanks for all the (sleeping) penguins.
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