[Arm-dev] We need to consider system time

[Robert Moskowitz]

On 12/20/2015 03:17 AM, Fabian Arrotin wrote:
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> On 20/12/15 04:12, Robert Moskowitz wrote:
>> Most armv7 boards lack a battery to maintain system time.  On
>> firstboot they come up a zero time.  This results in the initial
>> log files (and other key files) to have a zero date:
>>
>> # ls /var/log/ -lst total 260 84 -rw-------. 1 root root  82722 Dec
>> 19 21:45 messages 8 -rw-------. 1 root root   4889 Dec 18 16:27
>> secure 16 -rw-------. 1 root root  14517 Dec 18 16:01 cron 4
>> drwx------. 2 root root   4096 Dec 18 00:38 httpd 24 -rw-------. 1
>> root root  19279 Dec 18 00:37 yum.log 0 -rw-------. 1 root root
>> 0 Dec  3 09:07 spooler 0 -rw-------. 1 root root      0 Dec  3
>> 09:05 tallylog 4 drwx------. 2 root root   4096 May 28  2015 ppp 4
>> -rw-------. 1 root utmp   1152 Dec 31  1969 btmp 16 -rw-rw-r--. 1
>> root utmp  13824 Dec 31  1969 wtmp 4 -rw-------. 1 root root    200
>> Dec 31  1969 maillog 28 -rw-r--r--. 1 root root 292292 Dec 31  1969
>> lastlog 4 drwxr-xr-x. 2 root root   4096 Dec 31  1969 tuned 4
>> -rw-r--r--. 1 root root    120 Dec 31  1969 wpa_supplicant.log 4
>> drwxr-x---. 2 root root   4096 Dec 31  1969 audit 8 -rw-r--r--. 1
>> root root   8180 Dec 31  1969 boot.log 24 -rw-r--r--. 1 root root
>> 23322 Dec 31  1969 dmesg 24 -rw-r--r--. 1 root root  23322 Dec 31
>> 1969 dmesg.old
>>
>>
>> Logwatch will have problems with these files (or that has been my
>> prior experience).  I suspect other services will have problems
>> with such 'old' files on the system.
>>
>> First we need to select the time management service:  ntp or
>> timesync (I think I got this service naed correctly)?
> chronyd is the way tto go for el7, reason why I added it on the wiki
> page
> (https://wiki.centos.org/SpecialInterestGroup/AltArch/Arm32#head-d9feb4cde1956642a4a4e36b81a7e17b53a30805)
> and it seems to work for me on a reboot :
>
> Jan 01 01:00:23 rpi2 chronyd[187]: System clock wrong by
> 1450599058.242734 seconds, adjustment started
> Dec 20 09:11:21 rpi2 chronyd[187]: System clock was stepped by
> 1450599058.242734 seconds

OK.  that 'looks' good, but then chronyd needs to be in your base image 
so it is there for firstboot. Not 2nd boot, at best.  ;)

Time syncing is not a niceity on a batteryless Arm board like it is on a 
typical Intel board.  Hopefully this occurs 'soon enough' that we do not 
have log files and others with bad dates.

I will read up on chronyd to see if there is a way to seed it with a 
date from a file.  But perhaps others here already know how to do this?

>
>
>
>> Fedora is using timesync and gets the current proper time from the
>>   network shortly after bootup.  But there are some problems with
>> this that are not so much an issue for a desktop, but are for a
>> server.
>>
>> The firstboot timestamping problem I show above still occurs.
>> Fedora has a later version of timesync that has this function.  The
>>   version in Centos7 does not. What happens when a server restarts
>> after a power outage, but before the external network access is
>> available?  For some time the system runs with time zero+.
> True, as chronyd will need access to network (early in the boot
> process , through systemd) for that change .. we can investigate
> another way of doing that
>
>> Here is what I am thinking as the way to address this:
>>
>> The time services have the ability to read a file for a date hint
>> if the date is less than some set time, or that is what I
>> understand. So add to the centos-arm-installer script (to be made
>> for the fedora-arm-installer script) a set to get the date from the
>> installing system and pushing it into the proper place of the
>> centos7-arm image.
>>
>> Now at first boot, the system SHOULD come up with this date which
>> is at least a good start that will tend to not be too stale.
>>
>> Next this date file should be updated through some automatic
>> process so in the event that a system is turned off then reboots,
>> it comes up with a rather good start time.
>>
>> I don't know what would be a good way to do this on Centos7.  I can
>>   search back in my various discussions on this subject on a couple
>> of lists.  But there are people here that I hope are better able to
>> make the design decisions needed so that our Centos7-armv7 systems
>> have good time.
>>
> Keep us informed ;-)

I do tend to do that...