man: document that link-ed files must be on /

Fixes #8307.

diff --git a/man/systemctl.xml b/man/systemctl.xml
index c311548f4b02bf68ab9f043ebd0f2229b212cac6..1588ca719da17c9819020f2db8a85b8ffa99eadb 100644 (file)
--- a/man/systemctl.xml
+++ b/man/systemctl.xml
@@ -1120,7 +1120,10 @@ Jan 12 10:46:45 example.com bluetoothd[8900]: gatt-time-server: Input/output err
             automatically searched for unit files with appropriate names), or absolute paths to unit files (in which
             case these files are read directly). If a specified unit file is located outside of the usual unit file
             directories, an additional symlink is created, linking it into the unit configuration path, thus ensuring
-            it is found when requested by commands such as <command>start</command>.</para>
+            it is found when requested by commands such as <command>start</command>. The file system where the linked
+            unit files are located must be accessible when systemd is started (e.g. anything underneath
+            <filename>/home</filename> or <filename>/var</filename> is not allowed, unless those directories are
+            located on the root file system).</para>
 
             <para>This command will print the file system operations executed. This output may be suppressed by passing
             <option>--quiet</option>.
@@ -1350,7 +1353,10 @@ Jan 12 10:46:45 example.com bluetoothd[8900]: gatt-time-server: Input/output err
             <para>Link a unit file that is not in the unit file search paths into the unit file search path. This
             command expects an absolute path to a unit file. The effect of this may be undone with
             <command>disable</command>. The effect of this command is that a unit file is made available for commands
-            such as <command>start</command>, even though it is not installed directly in the unit search path.</para>
+            such as <command>start</command>, even though it is not installed directly in the unit search path. The
+            file system where the linked unit files are located must be accessible when systemd is started
+            (e.g. anything underneath <filename>/home</filename> or <filename>/var</filename> is not allowed, unless
+            those directories are located on the root file system).</para>
           </listitem>
         </varlistentry>