Will 10.2 also ship with a very stale NTP?
junchoon at dec.sakura.ne.jp
Thu Jul 16 12:58:06 UTC 2015
Confirmed MFC of ntp 4.2.8p3 and related kernel fix.
Thanks for your work!
Thanks for approving MFC at this timing, before creating releng/10.2.
Congraturations! We have latest stable version of ntp with 10.2. :-)
On Sun, 12 Jul 2015 12:48:49 -0600
Ian Lepore <ian at freebsd.org> wrote:
> On Mon, 2015-07-13 at 04:31 +1000, Peter Jeremy wrote:
> > On 2015-Jul-12 09:41:43 -0600, Ian Lepore <ian at freebsd.org> wrote:
> > >And let's all just hope that a week or two of testing is enough when
> > >jumping a major piece of software forward several years in its
> > >independent evolution.
> > Whilst I support John's desire for NTP to be updated, I also do not
> > think this is the appropriate time to do so. That said, the final
> > decision is up to re at .
> > >The import of 4.2.8p2 several months ago resulted in complete failure of
> > >timekeeping on all my arm systems. Just last week I tracked it down to
> > >a kernel bug (which I haven't committed the fix for yet). While the bug
> > >has been in the kernel for years, it tooks a small change in ntpd
> > >behavior to trigger it.
> > >
> > >Granted it's an odd corner-case problem that won't affect most users
> > >because they just use the stock ntp.conf file (and it only affects
> > >systems that have a large time step due to no battery-backed clock).
> > >But it took me weeks to find enough time to track down the cause of the
> > >problem.
> > I'm not using the stock ntp.conf on my RPis and didn't notice any NTP
> > issues. Are you able to provide more details of either the ntp.conf
> > options that trigger the bug or the kernel bug itself? A quick search
> > failed to find anything.
> I just committed the kernel fix as r285424; the commit message has some
> info on why the new ntpd made the problem visible.
> I should have said "stock rc.conf and ntp.conf"... To get the problem to
> happen you've got to set rc.conf ntpd_sync_on_start=NO and allow ntpd to
> make a large step (-g without -q, or tinker panic 0). I don't remember
> why I had sync on start disabled on most of my arm systems (probably a
> one-time experiment that I forgot to undo and it got copied around), but
> I suspect most people who don't have battery clocks will have it set to
> yes, and that's why nobody else saw this problem.
> To me, the problem was mainly illustrative of how a tiny innocuous
> change (ntpd making a series of ntp_adjtime() calls in a different, but
> still correct, order than it used to) can expose a completely unexpected
> longstanding bug in our code. Gotta wonder if any more of those are
> lurking. :/
> -- Ian
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Tomoaki AOKI junchoon at dec.sakura.ne.jp
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