+@subsection QEMU_AUDIO_ environment variables and -audio-help (since 4.0)
+
+The ``-audiodev'' argument is now the preferred way to specify audio
+backend settings instead of environment variables. To ease migration to
+the new format, the ``-audiodev-help'' option can be used to convert
+the current values of the environment variables to ``-audiodev'' options.
+
+@subsection -mon ...,control=readline,pretty=on|off (since 4.1)
+
+The @code{pretty=on|off} switch has no effect for HMP monitors, but is
+silently ignored. Using the switch with HMP monitors will become an
+error in the future.
+
+@subsection -realtime (since 4.1)
+
+The @code{-realtime mlock=on|off} argument has been replaced by the
+@code{-overcommit mem-lock=on|off} argument.
+
+@subsection -virtfs_synth (since 4.1)
+
+The ``-virtfs_synth'' argument is now deprecated. Please use ``-fsdev synth''
+and ``-device virtio-9p-...'' instead.
+