diff --git a/doc/openocd.texi b/doc/openocd.texi
index 12a8ca56d..03c5190ad 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -2180,6 +2180,9 @@ In such cases, just specify the relevant port number as "disabled".
 If you disable all access through TCP/IP, you will need to
 use the command line @option{-pipe} option.
 
+You can request the operating system to select one of the available
+ports for the server by specifying the relevant port number as "0".
+
 @anchor{gdb_port}
 @deffn {Config Command} {gdb_port} [number]
 @cindex GDB server