Re: 11 minute RTC update (was Re: Remove RTC UIP)

[Alessandro Zummo <alessandro.zummo@towertech.it>]

On Tue, 28 Mar 2006 19:21:37 -0600
Matt Mackall <mpm@selenic.com> wrote:

> > > With existing NTP setups, and the kernel no longer writing to the RTC,
> > > you might have the RTC drift far enough that NTP failed to sync on the
> > > next boot. (Correct me if I'm wrong, of course.)
> > 
> >  That's probably true, I'm not expert on the matter. The new subsystem only
> >  covers platforms that were not covered before (i.e. without external patches),
> >  so that this should not impact users because the NTP update mode
> >  was not working on them.
> > 
> >  The problem might arise when other RTC drivers (i.e. x86) will be converted
> >  and deployed.
> > 
> >  We need a migration plan. Any suggestion? 
> 
> I guess the question then becomes: is existing userspace (ntpd)
> already doing its own updates. If so, we can schedule the feature for
> removal in the near future. If not, it may take quite a bit longer.

 I think it isn't. Ideally ntpd should open /dev/rtcX and write the time,
 but I'm not sure if it belongs to it or if a simple hwclock --systohc /dev/rtcX
 should be used.

 Obviously hwclock needs to be updated to support multiple RTCs.

-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Turin, Italy

  http://www.towertech.it