man: document new systemd.volatile=overlay kernel command line option

[thirdparty/systemd.git] / man / kernel-command-line.xml

diff --git a/man/kernel-command-line.xml b/man/kernel-command-line.xml
index e39f108d8f4975ae1c5db90cb0b3b441c8613745..6e791192b2bbe7d9d02766f8cf665d6b7f9a1bf0 100644 (file)
--- a/man/kernel-command-line.xml
+++ b/man/kernel-command-line.xml
@@ -137,10 +137,13 @@
           enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
           configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
           well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
-          setting is set to <literal>state</literal> the root file system is mounted as usual, however
+          setting is set to <literal>state</literal> the root file system is mounted read-only, however
           <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
-          system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
-          see
+          system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. If
+          this setting is set to <literal>overlay</literal> the root file system is set up as
+          <literal>overlayfs</literal> mount combining the read-only root directory with a writable
+          <literal>tmpfs</literal>, so that no modifications are made to disk, but the file system may be modified
+          nonetheless with all changes being lost at reboot. For details, see
           <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
           and
           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>