From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 8 Jun 2023 08:33:36 +0000 (+0200)
Subject: man: document how calendar times catch up after system suspend/hibernation
X-Git-Tag: v254-rc1~254
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=438874cb105736e1fb59d67127c42a68f30bdf20;p=thirdparty%2Fsystemd.git

man: document how calendar times catch up after system suspend/hibernation

Fixes: #26166
---

diff --git a/man/systemd.timer.xml b/man/systemd.timer.xml
index b0aa5930f01..cdc9bca4c07 100644
--- a/man/systemd.timer.xml
+++ b/man/systemd.timer.xml
@@ -209,7 +209,16 @@
         adjusted to a network time source <emphasis>before</emphasis> the timer event is set up. Timer units
         with at least one <varname>OnCalendar=</varname> expression are automatically ordered after
         <filename>time-sync.target</filename>, which <filename>systemd-time-wait-sync.service</filename> is
-        ordered before.</para></listitem>
+        ordered before.</para>
+
+        <para>When a system is temporarily put to sleep (i.e. system suspend or hibernation) the realtime
+        clock does not pause. When a calendar timer elapses while the system is sleeping it will not be acted
+        on immediately, but once the system is later resumed it will catch up and process all timers that
+        triggered while the system was sleeping. Note that if a calendar timer elapsed more than once while
+        the system was continously sleeping the timer will only result in a single service activation. If
+        <varname>WakeSystem=</varname> (see below) is enabled a calendar time event elapsing while the system
+        is suspended will cause the system to wake up (under the condition the system's hardware supports
+        time-triggered wake-up functionality).</para></listitem>
       </varlistentry>
 
       <varlistentry>