From 91214a37ef4eb8042d2598aa89bae52b410d11a7 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 13 Dec 2016 12:45:19 +0100
Subject: fstab-generator: add support for volatile boots

This adds support for a new kernel command line option "systemd.volatile=" that
provides the same functionality that systemd-nspawn's --volatile= switch
provides, but for host systems (i.e. systems booting with a kernel).

It takes the same parameter and has the same effect.

In order to implement systemd.volatile=yes a new service
systemd-volatile-root.service is introduced that only runs in the initrd and
rearranges the root directory as needed to become a tmpfs instance. Note that
systemd.volatile=state is implemented different: it simply generates a
var.mount unit file that is part of the normal boot and has no effect on the
initrd execution.

The way this is implemented ensures that other explicit configuration for /var
can always override the effect of these options.  Specifically, the var.mount
unit is generated in the "late" generator directory, so that it only is in
effect if nothing else overrides it.
---
 man/systemd-nspawn.xml | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

(limited to 'man/systemd-nspawn.xml')

diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml
index 2bc81ea1aa..f6b3f57fc7 100644
--- a/man/systemd-nspawn.xml
+++ b/man/systemd-nspawn.xml
@@ -939,12 +939,15 @@
         <option>no</option> (the default), the whole OS tree is made
         available writable.</para>
 
-        <para>Note that setting this to <option>yes</option> or
-        <option>state</option> will only work correctly with
-        operating systems in the container that can boot up with only
-        <filename>/usr</filename> mounted, and are able to populate
-        <filename>/var</filename> automatically, as
-        needed.</para></listitem>
+        <para>This option provides similar functionality for containers as the <literal>systemd.volatile=</literal>
+        kernel command line switch provides for host systems. See
+        <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
+        details.</para>
+
+        <para>Note that enabling this setting will only work correctly with operating systems in the container that can
+        boot up with only <filename>/usr</filename> mounted, and are able to automatically populate
+        <filename>/var</filename>, and also <filename>/etc</filename> in case of
+        <literal>--volatile=yes</literal>.</para></listitem>
       </varlistentry>
 
       <varlistentry>
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