From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758550Ab3FTXLN (ORCPT ); Thu, 20 Jun 2013 19:11:13 -0400 Received: from h1446028.stratoserver.net ([85.214.92.142]:51340 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754296Ab3FTXLL (ORCPT ); Thu, 20 Jun 2013 19:11:11 -0400 Message-ID: <51C38BFE.9000405@ahsoftware.de> Date: Fri, 21 Jun 2013 01:10:54 +0200 From: Alexander Holler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: John Stultz CC: rtc-linux@googlegroups.com, linux-kernel@vger.kernel.org, Andrew Morton , Thomas Gleixner , Alessandro Zummo Subject: Re: [rtc-linux] Re: [PATCH 4/9 RESEND] RFC: timekeeping: introduce flag systime_was_set References: <51BA1FF7.4000206@ahsoftware.de> <1371228732-5749-1-git-send-email-holler@ahsoftware.de> <1371228732-5749-5-git-send-email-holler@ahsoftware.de> <51BB55C0.7090603@linaro.org> <51BB5B65.3000400@ahsoftware.de> <51BB60B1.6040007@linaro.org> <51BC034C.8080702@ahsoftware.de> <51BF5132.1060400@linaro.org> <51C2D62A.3060906@ahsoftware.de> <51C33B9B.7030600@linaro.org> <51C34DCC.8080501@ahsoftware.de> <51C357ED.7080409@linaro.org> In-Reply-To: <51C357ED.7080409@linaro.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 20.06.2013 21:28, schrieb John Stultz: >>> >>> But ntpd can be installed afterwards, and it would be silly to require >>> users edit their boot arguments when installing the ntp package. >>> > > This point you left un-addressed, and is the key problem I see with > requiring boot arguments. There is no requirement for an additional boot argument. That would only be necessary if you start ntpdate without using a persistent clock and before loading of (working) rtc-modules would have finished. And even then it would only be necessary if you use ntpdate (once) while a driver for the rtc is in it's registration phase and wants to set the clock or if you use ntp and the rtc which registers while ntp sets the time, has a time which would force ntp to refuse further adjustments. And in both cases only, if you don't have disabled the proposed hctosys with using a boot argument. Just because a boot argument makes it possible to disable hctosys by RTC doesn't mean it's necessary. Sorry for beeing pedantic, but I have to defend my decision to avoid locking just because of that possibility. I was fully aware of that unlikely race condition. Anyway, I've already accomplished to add locking to prevent that case. Regards, Alexander Holler