Introduce suspend-to-hibernate (#8274)

Suspend to Hibernate is a new sleep method that invokes suspend
for a predefined period of time before automatically waking up
and hibernating the system.

It's similar to HybridSleep however there isn't a performance
impact on every suspend cycle.

It's intended to use with systems that may have a higher power
drain in their supported suspend states to prevent battery and
data loss over an extended suspend cycle.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>

1 files changed, 28 insertions, 5 deletions

diff --git a/man/systemd-sleep.conf.xml b/man/systemd-sleep.conf.xml
index 7fecd667de..6ad9ff4b2b 100644
--- a/man/systemd-sleep.conf.xml
+++ b/man/systemd-sleep.conf.xml
@@ -60,7 +60,7 @@
   <refsect1>
     <title>Description</title>
 
-    <para><command>systemd</command> supports three general
+    <para><command>systemd</command> supports four general
     power-saving modes:</para>
 
     <variablelist>
@@ -102,6 +102,17 @@
         suspend-to-both by the kernel.
         </para></listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term>suspend-to-hibernate</term>
+
+        <listitem><para>A low power state where the system is initially suspended
+        (the state is stored in RAM). If not interrupted within the delay specified by
+        <command>HibernateDelaySec=</command>, the system will be woken using an RTC
+        alarm and hibernated (the state is then stored on disk).
+        </para></listitem>
+      </varlistentry>
+
     </variablelist>
 
     <para>Settings in these files determine what strings
@@ -134,8 +145,9 @@
         <filename>/sys/power/disk</filename> by,
         respectively,
         <citerefentry><refentrytitle>systemd-suspend.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
-        <citerefentry><refentrytitle>systemd-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, or
-        <citerefentry><refentrytitle>systemd-hybrid-sleep.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+        <citerefentry><refentrytitle>systemd-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>systemd-hybrid-sleep.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, or
+        <citerefentry><refentrytitle>systemd-suspend-to-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
         More than one value can be specified by separating
         multiple values with whitespace. They will be tried
         in turn, until one is written without error. If
@@ -152,14 +164,24 @@
         <filename>/sys/power/state</filename> by,
         respectively,
         <citerefentry><refentrytitle>systemd-suspend.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
-        <citerefentry><refentrytitle>systemd-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, or
-        <citerefentry><refentrytitle>systemd-hybrid-sleep.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+        <citerefentry><refentrytitle>systemd-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>systemd-hybrid-sleep.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, or
+        <citerefentry><refentrytitle>systemd-suspend-to-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
         More than one value can be specified by separating
         multiple values with whitespace. They will be tried
         in turn, until one is written without error. If
         neither succeeds, the operation will be aborted.
         </para></listitem>
       </varlistentry>
+      <varlistentry>
+        <term><varname>HibernateDelaySec=</varname></term>
+
+        <listitem><para>The amount of time in seconds
+        that will pass before the system is automatically
+        put into hibernate when using
+        <citerefentry><refentrytitle>systemd-suspend-to-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+        </para></listitem>
+      </varlistentry>
     </variablelist>
   </refsect1>
 
@@ -180,6 +202,7 @@ SuspendState=freeze</programlisting></para>
       <citerefentry><refentrytitle>systemd-suspend.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd-hybrid-sleep.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-suspend-to-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
     </para>