[698] in linux-net channel archive
Re: Getting and setting time for client, how?
daemon@ATHENA.MIT.EDU (Rob Janssen reading Linux mailingl)
Sat Jul 15 22:59:10 1995
From: linux@pe1chl.ampr.org (Rob Janssen reading Linux mailinglist)
To: TaRDiS@mail.utexas.edu (lilo)
Date: Sat, 15 Jul 1995 23:25:06 +0200 (MET DST)
Cc: linux-net@vger.rutgers.edu, jonathan@DSG.Stanford.EDU, drew@poohsticks.org,
GeisJ@rnd3.indy.tce.com
In-Reply-To: <Pine.LNX.3.91.950715062853.18681B-100000@slip-5-8.ots.utexas.edu> from "lilo" at Jul 15, 95 06:30:57 am
Reply-To: linux-vger@wab-tis.rabobank.nl
According to lilo:
> > With proper kernel patches it is possible to PLL this clock to a
> > pulse-per-second receiver that receives one of the time standard transmitters
> > available on Longwave or Shortwave.
> > I keep my clock within about 20us (day) or 200us (night) jitter from
> > one of these time standard signals. The jitter is caused mostly by
> > propagation effects, I think.
> > (I have sent the patches to Linus but they don't appear in the kernel
> > for some reason unknown to me)
>
> I'm also curious about this. I run xntpd and it would be very helpful
> IMO to have these patches integrated into the 1.3.x kernels.
>
> Speaking of which, where can I obtain your patches? I'm running 1.3.10
> at present....
My patches (actually they are written by Harald Koenig and I have only
updated them for the newest kernels) are not related to xntpd, but they
enable a system to be synchronized to a PPS clock receiver connected to
a serial port.
The patches merely enable timestamping of events on the serial port, and
a user-mode daemon reads the timestamps, evaluates the error of the local
clock, and controls it using the existing adjtimex call.
The patches are necessary to avoid errors caused by the scheduler.
(the daemon is not immediately scheduled when a character arrives, so
calling gettimeofday from the daemon to obtain the time difference between
the local system and the time standard is no good)
Originally the stuff by Harald Koenig was on:
ftp.informatik.tu-muenchen.de:/tmp/dcf77-koenig.tar.gz
I don't know if it is still there. I could send the patch on this list.
Rob
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