[systemd-devel] systemd-timesyncd with read-only root filesystem

[André Hartmann]

Hi Martin,

Am 04.12.2016 um 17:48 schrieb Martin Pitt:
> Hello André,
>
> André Hartmann [2016-12-01 11:20 +0100]:
>> In other words: once this symlink is valid, you cannot invalidate it by
>> make it a dangling symlink, you have to remove it. Can somebody confirm this
>> observation?
>
> Not a dangling one, but you should be able to make a symlink in /etc
> pointing to /dev/null. This is called "masking" and what "systemctl
> mask" does, and is sort of a stronger version of "disable" (in the
> sense that it will also not be started any more through Requires= and
> friends).

My main problem is that I cannot disable NTP by setting
the link to /dev/null as the root partition is read-only.

And till now I don't understand how timedatectl decides
"NTP enabled: yes/no". I need a possibility to disable NTP
in case the user will set the date by hand (also enabling
it again if the user decides otherwise).

Which confuses me is the inconsistency between
"systemctl status systemd.timesyncd" and "timedatectl status":

# systemctl status systemd.timesyncd
*  systemd.timesyncd.service
    Loaded: not-found (Reason: No such file or directory)
    Active: inactive (dead)

# timedatectl status
       Local time: Wed 2016-12-07 16:18:06 UTC
   Universal time: Wed 2016-12-07 16:18:06 UTC
         RTC time: n/a
        Time zone: Universal (UTC, +0000)
      NTP enabled: yes
NTP synchronized: no
  RTC in local TZ: no
       DST active: n/a

Any pointers here will be helpful. I assume read-only filesystems are 
common on embedded systems, so I assume somebody already run into this 
issue?!

Thanks, André

[1] systemd 219
+PAM -AUDIT -SELINUX +IMA -APPARMOR +SMACK +SYSVINIT +UTMP
-LIBCRYPTSETUP -GCRYPT +GNUTLS +ACL +XZ -LZ4 -SECCOMP +BLKID
-ELFUTILS +KMOD +IDN

-- 
Best regards / Mit freundlichen Grüßen
André Hartmann, Dipl.-Ing. (FH)
Software Project Manager

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