From owner-cvs-src@FreeBSD.ORG Mon Apr 7 02:26:09 2003 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 791C637B401; Mon, 7 Apr 2003 02:26:09 -0700 (PDT) Received: from cirb503493.alcatel.com.au (c18609.belrs1.nsw.optusnet.com.au [210.49.80.204]) by mx1.FreeBSD.org (Postfix) with ESMTP id B73C943F75; Mon, 7 Apr 2003 02:26:07 -0700 (PDT) (envelope-from peterjeremy@optushome.com.au) Received: from cirb503493.alcatel.com.au (localhost.alcatel.com.au [127.0.0.1])h379Q5M2041536; Mon, 7 Apr 2003 19:26:05 +1000 (EST) (envelope-from jeremyp@cirb503493.alcatel.com.au) Received: (from jeremyp@localhost) by cirb503493.alcatel.com.au (8.12.8/8.12.8/Submit) id h379Q3FT041535; Mon, 7 Apr 2003 19:26:03 +1000 (EST) Date: Mon, 7 Apr 2003 19:26:02 +1000 From: Peter Jeremy To: Poul-Henning Kamp Message-ID: <20030407092602.GA41279@cirb503493.alcatel.com.au> References: <20030407163148.L3478@gamplex.bde.org> <4145.1049705887@critter.freebsd.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4145.1049705887@critter.freebsd.dk> User-Agent: Mutt/1.4.1i cc: cvs-src@freebsd.org cc: src-committers@freebsd.org cc: cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/conf options.i386 src/sys/i386/i386 tsc.c src/sys/i386/conf NOTES X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Apr 2003 09:26:09 -0000 On Mon, Apr 07, 2003 at 10:58:07AM +0200, Poul-Henning Kamp wrote: >The best result I have had so far, and the only one I have sufficient >faith in to advocate its use in general, takes an entirely different >route: > >The RTC interrupts us at 128Hz for statclock, divide this in software >to get 1Hz and take timestamps and feed them to the NTP kernel-FLL code >and tell NTPD to lock to that at a high stratum. Given that this clock is effectively free-running compared to real time, could this cause the kernel clock to jump if ntpd switches to/from this clock source? Do you have patches available to do this? I know I did something similar in 2.2 but never keep the code up to date and I think I've lost it. >[1] fun fact: The 14.318MHz is four times the color burst frequency >of NTSC television signals, fun fact 2: 4.77MHz is 14.318MHz/3. The divide-by-3 is because the i8284 (8086/88 clock generator chip) divides the crystal by 3 to generate the system clock. This means the CGA could use the crystal on the motherboard (though I don't know if it did actually use the ISA clock). > and was chosen by IBM for the original >IBM PC because it made it possible to generate four different colors >in a purely digital fasion on a television connected to the CGA. I think Apple was the first to make use of this. Peter