udev: clarify man page regarding starting dameons

TODO

@@ -19,17 +19,20 @@ Features:
 
 * cg_create_and_attach() should fail for non-available controllers
 
-* make gtk-doc optional (like kmod?)
+* udevd: SIGKILL all non-udevd processes in udev.service cgroup when entering idle
+  (the time to be able start services from udev rules is over on systemd systems)
 
-* udev: find a way to tell udev to not cancel firmware requests in initramfs
+* udev: remove /sys and /dev configurability
 
-* udev: scsi_id -> sg3_utils?
+* udev: find a way to tell udev to not cancel firmware requests when running in initramfs
 
-* udev: add trigger --subsystem-match=usb/usb_device
+* udev: scsi_id -> sg3_utils -> kill scsi_id
+
+* udev: add trigger --subsystem-match=usb/usb_device device
 
 * udev: libudev.so.1
-  - remove deprecated symbols
   - use symbol versioning
+  - remove deprecated symbols
   - return object with *_unref()
   - kill: udev_monitor_from_socket()
   - kill: udev_queue_get_failed_list_entry()

man/udev.xml

@@ -287,6 +287,8 @@
             successfully. The device properties are made available to the
             executed program in the environment. The program's stdout
             is available in the RESULT key.</para>
+            <para>This can only be used for very short-running foreground tasks. For details
+            see <option>RUN</option>.</para>
           </listitem>
         </varlistentry>
 
@@ -401,10 +403,12 @@
             /usr/lib/udev, otherwise the absolute path must be specified. The program
             name and following arguments are separated by spaces. Single quotes can
             be used to specify arguments with spaces.</para>
-            <para>This can only be used for very short running tasks. Running an
+            <para>This can only be used for very short-running foreground tasks. Running an
             event process for a long period of time may block all further events for
-            this or a dependent device. Starting daemons or other long running processes
-            is not appropriate for udev.</para>
+            this or a dependent device.</para>
+            <para>Starting daemons or other long running processes is not appropriate
+            for udev; the forked processes, detached or not, will be unconditionally
+            killed after the event handling has finished.</para>
           </listitem>
         </varlistentry>
 
@@ -470,6 +474,8 @@
                 </listitem>
               </varlistentry>
             </variablelist>
+            <para>This can only be used for very short-running foreground tasks. For details
+            see <option>RUN</option>.</para>
           </listitem>
         </varlistentry>