From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94EFAC4646B for ; Tue, 25 Jun 2019 01:53:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C00720665 for ; Tue, 25 Jun 2019 01:53:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730196AbfFYBx6 (ORCPT ); Mon, 24 Jun 2019 21:53:58 -0400 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:59876 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729450AbfFYBx6 (ORCPT ); Mon, 24 Jun 2019 21:53:58 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by kvm5.telegraphics.com.au (Postfix) with ESMTP id 7913729AF7; Mon, 24 Jun 2019 21:53:52 -0400 (EDT) Date: Tue, 25 Jun 2019 11:53:49 +1000 (AEST) From: Finn Thain To: Alexandre Belloni cc: Alessandro Zummo , userm57@yahoo.com, linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rtc: Don't state that the RTC holds UTC in case it doesn't In-Reply-To: <20190624195705.GD5690@piout.net> Message-ID: References: <3e1e24a326b8b623b1a8b66a905ac6494ef74a07.1561081886.git.fthain@telegraphics.com.au> <20190624195705.GD5690@piout.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org On Mon, 24 Jun 2019, Alexandre Belloni wrote: > On 21/06/2019 11:51:26+1000, Finn Thain wrote: > > Some machines store local time in the Real Time Clock. The hard-coded > > "UTC" string is wrong on those machines so just omit that string. > > Update the log parser so it doesn't require the string "UTC". > > > > I don't agree, hctossys will always think the RTC is in UTC. Well, I wasn't speculating about a theoretical problem. This is a bug that was reported to me by a user of Debian/powerpc system. I was able to confirm that the bug also affects dual-boot Windows/Linux on x86 with CONFIG_RTC_HCTOSYS=y. > If you store local time in the RTC, then you are probably not using > hctosys because it definitively doesn't know about the timezone and will > incorrectly set the system time. That information is usually kept in > /etc/adjtime. > In the Debian/powerpc bug report, the timezone is obtained from the NVRAM: [ 0.000000] PowerMac motherboard: PowerBook Wallstreet ... [ 0.000000] GMT Delta read from XPRAM: -360 minutes, DST: on ... [ 37.605859] rtc-generic rtc-generic: rtc core: registered rtc-generic as rtc0 ... [ 40.346255] rtc-generic rtc-generic: setting system clock to 2019-06-19 15:17:35 UTC (1560957455) ... Though I don't know whether the sys_tz value is relevant here. Anyway, here's the bug reproduced on x86 -- # dmesg | grep rtc_cmos [ 0.543878] rtc_cmos 00:02: RTC can wake from S4 [ 0.544090] rtc_cmos 00:02: rtc core: registered rtc_cmos as rtc0 [ 0.544090] rtc_cmos 00:02: alarms up to one month, y3k, 114 bytes nvram, hpet irqs [ 0.545807] rtc_cmos 00:02: setting system clock to 2019-06-25 11:24:14 UTC (1561461854) # grep . /etc/adjtime /etc/timezone /etc/adjtime:0.000120 1550184138 0.000000 /etc/adjtime:1550184138 /etc/adjtime:LOCAL /etc/timezone:Australia/Melbourne # hwclock --show 2019-06-25 11:47:49.702660+10:00 # date --iso-8601=s 2019-06-25T11:48:01+10:00 # Looks wrong to me. What am I missing? -- > > Signed-off-by: Finn Thain > > --- > > drivers/rtc/hctosys.c | 2 +- > > tools/power/pm-graph/bootgraph.py | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/rtc/hctosys.c b/drivers/rtc/hctosys.c > > index ff2092a0d38c..2270eca23203 100644 > > --- a/drivers/rtc/hctosys.c > > +++ b/drivers/rtc/hctosys.c > > @@ -58,7 +58,7 @@ static int __init rtc_hctosys(void) > > > > err = do_settimeofday64(&tv64); > > > > - dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n", > > + dev_info(rtc->dev.parent, "setting system clock to %ptR (%lld)\n", > > &tm, (long long)tv64.tv_sec); > > > > err_read: > > diff --git a/tools/power/pm-graph/bootgraph.py b/tools/power/pm-graph/bootgraph.py > > index 6dae57041537..5a045d1cb879 100755 > > --- a/tools/power/pm-graph/bootgraph.py > > +++ b/tools/power/pm-graph/bootgraph.py > > @@ -333,7 +333,7 @@ def parseKernelLog(): > > if(not sysvals.stamp['kernel']): > > sysvals.stamp['kernel'] = sysvals.kernelVersion(msg) > > continue > > - m = re.match('.* setting system clock to (?P.*) UTC.*', msg) > > + m = re.match('.* setting system clock to (?P.*) (?:UTC )?\(.*', msg) > > if(m): > > bt = datetime.strptime(m.group('t'), '%Y-%m-%d %H:%M:%S') > > bt = bt - timedelta(seconds=int(ktime)) > > -- > > 2.21.0 > > > > -- > Alexandre Belloni, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com >