From: J William Piggott <elseifthen@gmx.com> To: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Cc: Karel Zak <kzak@redhat.com>, util-linux@vger.kernel.org, Linux List Kernel Mailing <linux-kernel@vger.kernel.org>, linux-rtc@vger.kernel.org Subject: Re: [bugreport] "hwclock -w" reset time instead of setting the right time Date: Thu, 2 Jan 2020 11:58:58 -0500 (EST) Message-ID: <nycvar.YAK.7.76.2001021153220.1385@zhn.tzk.pbz> (raw) In-Reply-To: <CABXGCsMV1GRiqrXCQGHqvpBiendU3mG36h0YoG=4nw6spZHq=w@mail.gmail.com> On Thu, 2 Jan 2020, Mikhail Gavrilov wrote: > On Thu, 2 Jan 2020 at 18:14, Karel Zak <kzak@redhat.com> wrote: >> >> At first glance it seems hwclock works as expected, I do not see >> anything wrong in the output. >> >>> Demonstration: https://youtu.be/Yx27IH2opEc >> >> What is hw time before reboot? Can you verify that hwclock reset the >> clock? (or is it system reboot?) >> >> # hwclock -w -v >> # hwclock -v >> >> Do you see anything interesting in dmesg output before reboot and after >> hwclock -w? >> >> > > Yes, before reboot all look like good: > > [root@localhost ~]# hwclock -v > hwclock from util-linux 2.35-rc1-20-63f8 > System Time: 1577977370.909455 > Trying to open: /dev/rtc0 > Using the rtc interface to the clock. > Last drift adjustment done at 1577973311 seconds after 1969 > Last calibration done at 1577973311 seconds after 1969 > Hardware clock is on UTC time > Assuming hardware clock is kept in UTC time. > Waiting for clock tick... > ...got clock tick > Time read from Hardware Clock: 2020/01/02 15:02:52 > Hw clock time : 2020/01/02 15:02:52 = 1577977372 seconds since 1969 > Time since last adjustment is 4061 seconds > Calculated Hardware Clock drift is 0.000000 seconds > 2020-01-02 20:02:51.077494+05:00 > > > [root@localhost ~]# hwclock -w -v > hwclock from util-linux 2.35-rc1-20-63f8 > System Time: 1577977383.789039 > Trying to open: /dev/rtc0 > Using the rtc interface to the clock. > Last drift adjustment done at 1577973311 seconds after 1969 > Last calibration done at 1577973311 seconds after 1969 > Hardware clock is on UTC time > Assuming hardware clock is kept in UTC time. > RTC type: 'rtc_cmos' > Using delay: 0.500000 seconds > missed it - 1577977383.789405 is too far past 1577977383.500000 > (0.289405 > 0.001000) > 1577977384.500000 is close enough to 1577977384.500000 (0.000000 < 0.002000) > Set RTC to 1577977384 (1577977383 + 1; refsystime = 1577977383.000000) > Setting Hardware Clock to 15:03:04 = 1577977384 seconds since 1969 > ioctl(RTC_SET_TIME) was successful. > Not adjusting drift factor because the --update-drift option was not used. > New /etc/adjtime data: > 0.000000 1577977383 0.000000 > 1577977383 > UTC > > > [root@localhost ~]# hwclock -v > hwclock from util-linux 2.35-rc1-20-63f8 > System Time: 1577977389.540630 > Trying to open: /dev/rtc0 > Using the rtc interface to the clock. > Last drift adjustment done at 1577977383 seconds after 1969 > Last calibration done at 1577977383 seconds after 1969 > Hardware clock is on UTC time > Assuming hardware clock is kept in UTC time. > Waiting for clock tick... > ...got clock tick > Time read from Hardware Clock: 2020/01/02 15:03:10 > Hw clock time : 2020/01/02 15:03:10 = 1577977390 seconds since 1969 > Time since last adjustment is 7 seconds > Calculated Hardware Clock drift is 0.000000 seconds > 2020-01-02 20:03:09.718222+05:00 > > But after reboot, the hwtime is reset: > > === Reboot === > > > [root@localhost ~]# hwclock -v > hwclock from util-linux 2.35-rc1-20-63f8 > System Time: 1576407103.342223 > Trying to open: /dev/rtc0 > Using the rtc interface to the clock. > Last drift adjustment done at 1577977383 seconds after 1969 > Last calibration done at 1577977383 seconds after 1969 > Hardware clock is on UTC time > Assuming hardware clock is kept in UTC time. > Waiting for clock tick... > ...got clock tick > Time read from Hardware Clock: 2019/01/01 00:05:31 > Hw clock time : 2019/01/01 00:05:31 = 1546301131 seconds since 1969 > Time since last adjustment is -31676252 seconds > Calculated Hardware Clock drift is 0.000000 seconds > 2019-01-01 05:05:30.170661+05:00 > > [root@localhost ~]# date > Sun 15 Dec 2019 03:52:01 PM +05 > > > Demonstration: https://youtu.be/X0w2hbAmKmM You've demonstrated that 'hwclock -w' does not 'reset' the RTC. Does your new motherboard use a battery backup for the RTC? Is the battery good? > > > -- > Best Regards, > Mike Gavrilov. >
next prev parent reply index Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <CABXGCsODr3tMpQxJ_nhWQQg5WGakFt4Yu5B8ev6ErOkc+zv9kA@mail.gmail.com> [not found] ` <20200101141748.GA191637@mit.edu> [not found] ` <CABXGCsOv26W6aqB5WPMe-mEynmwy55DTfTeL5Dg9vRq6+Y6WvA@mail.gmail.com> 2020-01-02 8:08 ` Mikhail Gavrilov 2020-01-02 11:08 ` Karel Zak 2020-01-02 11:55 ` Mikhail Gavrilov 2020-01-02 13:14 ` Karel Zak 2020-01-02 15:00 ` Mikhail Gavrilov 2020-01-02 16:58 ` J William Piggott [this message] 2020-01-02 17:17 ` Mikhail Gavrilov 2020-01-03 10:02 ` Alexandre Belloni 2020-01-03 10:11 ` Mikhail Gavrilov 2020-01-03 10:19 ` Alexandre Belloni 2020-01-03 14:22 ` Mikhail Gavrilov 2020-01-04 5:44 ` Jinke Fan 2020-01-04 8:25 ` Mikhail Gavrilov 2020-01-04 11:35 ` Jinke Fan 2020-01-04 12:23 ` Mikhail Gavrilov
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