[time-nuts] Leap Quirks

M. Warner Losh imp at bsdimp.com
Sat Jan 3 17:21:29 UTC 2009


In message: <495F7285.3040003 at erols.com>
            Chuck Harris <cfharris at erols.com> writes:
: christopher hoover wrote:
: > Hal Murray wrote: 
: >> Two of my Linux systems hung.  One was running a 2.6.25 kernel and one
: >> 2.6.26.  A system running 2.6.23 worked fine.  I saw a couple of notes
: >> on
: >> comp.protocols.time.ntp about Linux systems locking up.  One said that
: >> it was
: >> a kernel bug in ntp.c but I haven't seen any details.
: > 
: > None of mine (many dozens) hung.    This is typical:
: > 
: > ch at snaggle:~$ uname -a
: > Linux snaggle.murgatroid.com 2.6.26-1-amd64 #1 SMP Mon Dec 15 19:40:58 UTC
: > 2008 x86_64 GNU/Linux
: > ch at snaggle:~$ dmesg | grep leap 
: > [844362.415072] Clock: inserting leap second 23:59:60 UTC
: > ch at snaggle:~$
: > 
: > 
: > -ch
: 
: None of my linux systems hung either!  My typical message was:
: 
: $ dmesg | grep leap
: [6181904.453104] Clock: inserting leap second 23:59:60 UTC
: 
: The message implies that linux clocks counted:
: 
: 58..59..60..00..01
: 
: Which would not be the POSIX way.

That message doesn't imply that at all...  Well, maybe it is the
implication, but POSIX *CANNOT* count that way.  It is number where
23:59:60 maps to, through normalization and *mktime, 00:00:00 (or maps
to 23:59:59 if you are ticking time, which isn't required to do the
mktime stuff).

Warner





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