<div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial"><div style="margin: 0;">hi Michal & Kevin,</div><div style="margin: 0;"><br></div><div style="margin: 0;">I find that just shutting down *timesync* service can't solve the problem. Build time also affects system time.</div><div style="margin: 0;">My testing process is as follows:</div><div style="margin: 0;">1. systemctl disable systemd-timesyncd</div><div style="margin: 0;"> systemctl mask systemd-timesyncd</div><div style="margin: 0;">2. timedatectl set-time "<b>2001</b>-11-30 17:36:46" --- This time is set years ago.</div><div style="margin: 0;">3. reboot system</div><div style="margin: 0;"><br></div><div style="margin: 0;"><b>View system time after startup</b>：</div><div style="margin: 0;"><div style="margin: 0;"><i>root@demoboard:~# timedatectl</i></div><div style="margin: 0;"><i> Local time: <b>Thu 2020-04-02 17:27:03 CST </b></i><b><i>This time is not the latest time, but it is not the time I set.</i></b><i><b> </b></i></div><div style="margin: 0;"><i> Universal time: <b>Thu 2020-04-02 09:27:03 UTC</b></i></div><div style="margin: 0;"><i> RTC time: n/a</i></div><div style="margin: 0;"><i> Time zone: Asia/Shanghai (CST, +0800)</i></div><div style="margin: 0;"><i>System clock synchronized: no</i></div><div style="margin: 0;"><i> NTP service: <b>n/a</b></i></div><div style="margin: 0;"><i> RTC in local TZ: no</i></div><div style="margin: 0;"><i>root@demoboard:~#</i></div></div><div style="margin: 0;"><br></div><div style="margin: 0;"><b>check the boot log:</b></div><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:24:52 demoboard systemd[1]: </span><span style="font-size: 12px; color: rgb(53, 94, 147);"><b>System time before build time, advancing clock</b></span><span style="font-size: 12px;"><b>. </b></span></div><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:25:02 demoboard systemd[1]: </span><span style="font-size: 12px; color: rgb(53, 94, 147);">logrotate.timer: Not using persistent file timestamp Sat 2020-04-25 13:45:26 CST as it is in the future</span><span style="font-size: 12px;">.</span></div><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:25:04 demoboard systemd[1]: Reached target Timers.</span></div><div style="margin: 0;"><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:25:38 demoboard systemd[1]: Starting Time & Date Service...</span></div><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:25:40 demoboard systemd[1308]: systemd-timedated.service: ProtectHostname=yes is configured, but the kernel does not support UTS namespaces, ignoring namespace setup.</span></div><div style="margin: 0;"><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:25:42 demoboard systemd[1]: Started Time & Date Service.</span></div><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:26:13 demoboard systemd[1]: systemd-timedated.service: Succeeded.</span></div><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:27:03 demoboard systemd[1]: Starting Time & Date Service...</span></div><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:27:03 demoboard systemd[1823]: systemd-timedated.service: ProtectHostname=yes is configured, but the kernel does not support UTS namespaces, ignoring namespace setup.</span></div><div style="margin: 0;"><span style="font-size: 12px;">Apr 02 17:27:03 demoboard systemd[1]: Started Time & Date Service.</span></div></div></div><div style="margin: 0;"><br></div><p style="margin: 0;">It can be seen from the log that after the TimeSync service is disabled, the latest time is obtained from NTP server, but it is<b> not updated to the system</b>. But the system time has also been modified.</p><p style="margin: 0;"><br></p><div style="margin: 0;">I'd like to ask you a few questions：</div><div style="margin: 0;">1. When I shut down the TimeSync service, who modified the system time and according to what?</div><div style="margin: 0;"><br></div><div style="margin: 0;">2. What time does the time in systemd relate to? such as build time。</div><div style="margin: 0;"><br></div><div style="margin: 0;">3. How to realize the time of completely independent control system, no matter TimeSync and build time？</div><div style="margin: 0;"><br></div><div style="margin: 0;">thanks，</div><div style="margin: 0;">Byron</div><div style="position:relative;zoom:1"></div><div id="divNeteaseMailCard"></div><p style="margin: 0;"><br></p><pre><br>At 2020-04-23 14:25:38, "Michał Zegan" <webczat_200@poczta.onet.pl> wrote:
>As I said, there are symlinks in /etc/systemd/system/*.target.wants that
>allows disabling services like this one from starting. It is enough to
>remove the one for systemd-timesync.service from multi-user.target.wants
>directory. If you can do things via some config files you should also be
>able to do this
>
>W dniu 23.04.2020 o 04:14, www pisze:
>>
>> hi Michal and Kevin,
>>
>> We applied systemd to embedded Linux, so we often need to update/flash
>> the whole system. When we select disable *time synchronization*
>> function, the embedded system will use the time itself. After we update
>> the system and restart it, we need the *time synchronization* function
>> is disabled. During the whole startup process, there is no automatic
>> time synchronization, and *the previous time is used*. Because automatic
>> time synchronization may change its original time. （*Because the time
>> of the system itself may be different from that of NTP time.*）
>>
>> There is a *timesyncd.conf* file under the system，can the system
>> automatically turn off the time synchronization function by modifying
>> this file?
>> In this way, when updating, I can save this file to solve this problem.
>>
>>
>> thanks,
>> Byron
>>
>>
>>
>>
>> At 2020-04-17 19:44:48, "Michał Zegan" <webczat_200@poczta.onet.pl> wrote:
>>>I am not quite sure what you mean, but... generally these are symlinks
>>>in /etc/systemd/system/multi-user.target.wants/ so you could delete them
>>>manually if your intention is to make the actual os image with this
>>>disabled from the start...
>>>
>>>W dniu 17.04.2020 o 12:10, www pisze:
>>>>
>>>> I mean that this configuration can be preserved, even after I update the
>>>> system, this function can be saved.
>>>>
>>>> thanks，
>>>> Byron
>>>>
>>>>
>>>>
>>>>
>>>> At 2020-04-17 18:06:15, "Kevin P. Fleming" <kevin@km6g.us> wrote:
>>>>>Both of those changes will stop the service from being started, even
>>>>>when the system is rebooted. You don't need to run these commands
>>>>>every time, running them one time will change the system configuration
>>>>>and the service will no longer be started.
>>>>>
>>>>>On Fri, Apr 17, 2020 at 2:52 AM www <ouyangxuan10@163.com> wrote:
>>>>>>
>>>>>> hi Kevin ,
>>>>>>
>>>>>> Thank you very much for you help. But how can I save this way of closing time synchronization by command after system boot up? After I update the system, the first time I start it, time synchronization is still enabled by default. It's not appropriate if I close it alone every time. So when I need it start every time, this function is off.
>>>>>>
>>>>>>
>>>>>> thanks,
>>>>>> Byron
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> At 2020-04-16 18:28:30, "Kevin P. Fleming" <kevin@km6g.us> wrote:
>>>>>> >There is no need to modify systemd.
>>>>>> >
>>>>>> >$ systemctl disable systemd-timesyncd
>>>>>> >
>>>>>> >That command will stop the systemd-timesyncd service from being
>>>>>> >started. It may also be necessary to mask it:
>>>>>> >
>>>>>> >$ systemctl mask systemd-timesyncd
>>>>>> >
>>>>>> >On Thu, Apr 16, 2020 at 6:22 AM www <ouyangxuan10@163.com> wrote:
>>>>>> >>
>>>>>> >> Dear all，
>>>>>> >>
>>>>>> >> I want to ask a question，How to modify systemd so that the NTP function is disabled when systemd is first started?
>>>>>> >>
>>>>>> >> The default state of systend is to synchronize time from NTP. We can use timedatectl command to disable NTP synchronize time. But if I flash the system, the NTP synchronize time function will auto enable. so I want modify the systemd and disable NTP synchronize time in default state.
>>>>>> >>
>>>>>> >> thanks,
>>>>>> >> Byron
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> _______________________________________________
>>>>>> >> systemd-devel mailing list
>>>>>> >> systemd-devel@lists.freedesktop.org
>>>>>> >> https://lists.freedesktop.org/mailman/listinfo/systemd-devel
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> systemd-devel mailing list
>>>> systemd-devel@lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/systemd-devel
>>>>
>>>
>>
>>
>>
>>
>>
>
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