From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominique Michel Subject: Re: daylight saving makes computer wake up late Date: Sun, 8 Apr 2007 21:50:37 +0200 Message-ID: <20070408215037.425b4883@localhost> References: <135ab3ff0704080512k2bcf3973m46c8153ff6a6f7df@mail.gmail.com> <20070408141040.GA14308@khazad-dum.debian.net> <135ab3ff0704081118g3bebd25bj7394483a50549dea@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail.alinto.citycable.ch ([85.218.0.111]:39454 "HELO citycable.ch" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1751975AbXDHT5M convert rfc822-to-8bit (ORCPT ); Sun, 8 Apr 2007 15:57:12 -0400 In-Reply-To: <135ab3ff0704081118g3bebd25bj7394483a50549dea@mail.gmail.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Morten Friesgaard , linux-acpi@vger.kernel.org Le Sun, 8 Apr 2007 20:18:28 +0200, "Morten Friesgaard" a =C3=A9crit : > I'm not sure what to do, how do I make these changes? >=20 > when I run the following it gives me somewhat the same values, but it > seems the BIOS clock i different (?!) > # hwclock ; date > Sun Apr 8 20:13:56 2007 -0.069330 seconds > Sun Apr 8 20:13:55 CEST 2007 >=20 > it worked before daylight savings, is it something I can ignore and > still get it to wake up the corret time? >=20 > should I change > TIMEZONE=3D"Europe/Copenhagen" >=20 > to > TIMEZONE=3D"UTC" > ?? >=20 > /Morten >=20 You must have 2 things: CLOCK=3D"UTC" TIMEZONE=3D"Europe/Copenhagen" The first one tell the OS that the rtc use UTC time, the second one at = it must convert the UTC time into Europe/Copenhagen time to get the current sys= tem time. On gentoo I also have an option that set the Hardware Clock to the curr= ent System Time during shutdown: CLOCK_SYSTOHC=3D"yes" Some linux distributions use CLOCK=3D"local" because, I guess, they are thinking at it is best to do so when you are double booting with window= s. It is wrong because when the rtc use local time, the system have to change th= e time in the rtc (read in the hardware) when the daylight is changing, and ea= ch OS will change the time in the rtc.=20 So, you will get the correct time after booting the first OS, a shift o= f one hour after booting the second OS, and so on. It is much simpler to use = UTC with all the OS in the box, and that even with window$ (it is an option= in the register base, I don't remember where but a google search will give you= the reference.) With CLOCK=3D"UTC", the time in the rtc (in the hardware) will never ch= ange, the OS will just interpret it with the value of TIMEZONE. Ciao, Dominique >=20 > On 08/04/07, Henrique de Moraes Holschuh wrote: > > On Sun, 08 Apr 2007, Morten Friesgaard wrote: > > > I'm running a mythbox, and ever since we had our yearly change of > > > daylight savings (summer time) my computer wakes up late. At firs= t it > > > was only an hour, then I set the time with hwclock (realised that > > > CLOCK_SYSTOHC=3D"no"), now it is 2 hours late. And it is really p= recise > > > (1-2 hours later), and it is certainly because of daylight saving= s. > > > > > > Any ideas? > > > > My guess is that you have to set ACPI wake times to *exactly* the t= ime zone > > you use your RTC in. Typically UTC, but semi-broken MS-compatible = setups > > use the local time zone. > > > > The kernel can know the timezone, but almost nobody ever sets that = right, > > and it is not summer-time aware anyway (too complex). It is best t= o just > > keep everything UTC as far as the kernel goes, *including* the RTC. > > > > -- > > "One disk to rule them all, One disk to find them. One disk to br= ing > > them all and in the darkness grind them. In the Land of Redmond > > where the shadows lie." -- The Silicon Valley Tarot > > Henrique Holschuh > > > - > To unsubscribe from this list: send the line "unsubscribe linux-acpi"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html --=20 Dominique Michel -- N.B.: Tous les emails que je re=C3=A7ois sont filtr=C3=A9s par spamassa= ssin avant de me parvenir. - To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html