man: mention new OPTIONS=log_level= udev rule

1 files changed, 18 insertions, 0 deletions

diff --git a/man/udev.xml b/man/udev.xml
index 14e4c21aae..c3168b0864 100644
--- a/man/udev.xml
+++ b/man/udev.xml
@@ -647,6 +647,24 @@
                     on the transition from initramfs.</para>
                   </listitem>
                 </varlistentry>
+                <varlistentry>
+                  <term><option>log_level=<replaceable>level</replaceable></option></term>
+                  <listitem>
+                    <para>Takes a log level name like <literal>debug</literal> or
+                    <literal>info</literal>, or a special value <literal>reset</literal>. When a log
+                    level name is specified, the maximum log level is changed to that level. When
+                    <literal>reset</literal> is set, then the previously specified log level is
+                    revoked. Defaults to the log level of the main process of
+                    <command>systemd-udevd</command>.</para>
+                    <para>This may be useful when debugging events for certain devices. Note that the
+                    log level is applied when the line including this rule is processed. So, for
+                    debugging, it is recommended that this is specified at earlier place, e.g., the
+                    first line of <filename>00-debug.rules</filename>.</para>
+                    <para>Example for debugging uevent processing for network interfaces.
+                    <programlisting># /etc/udev/rules.d/00-debug-net.rules
+SUBSYSTEM=="net", OPTIONS="log_level=debug"</programlisting></para>
+                  </listitem>
+                </varlistentry>
               </variablelist>
             </listitem>
           </varlistentry>