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Date: Sat, 5 May 2012 12:02:59 +0200
From: Richard Cochran <richardcochran@gmail.com>
To: John Stultz <john.stultz@linaro.org>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/1] ntp: advertise correct TAI offset during leap
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On Tue, May 01, 2012 at 08:16:05AM +0200, Richard Cochran wrote:
> On Mon, Apr 30, 2012 at 12:48:22PM -0700, John Stultz wrote:
> > On 04/27/2012 11:17 PM, Richard Cochran wrote:
> > >
> > >Wait a minute. If user space manages this variable, then shouldn't the
> > >kernel leave it alone?
> > 
> > Right. That's why I'm asking. I actually haven't spent much time
> > looking at how the tai value provided via adjtimex is handled, and I
> > want to make sure its ok if we modify it from the kernel.
> 
> We *are* already modifying it in kernel, but at the wrong time.
> 
> I don't know either what ntpd does, but I will find out.
> 
> [ But if ntpd just uses adjtimex() to use the kernel as storage for
>   variables, then that is really stupid. ]

I took a look at ntp-4.2.6p5, and ntpd unconditionally sets the TAI
offset using MOD_TAI when it thinks the offset has changed.

But I think it won't hurt if the kernel changes the offset
automatically, since ntpd will just try and set the same value again.

Thanks,
Richard