diff --git a/runtime/doc/channel.txt b/runtime/doc/channel.txt
index a306abb..01756f1 100644
--- a/runtime/doc/channel.txt
+++ b/runtime/doc/channel.txt
@@ -633,8 +633,8 @@
 		is going on in real time.
 
 		To enable the log very early, to see what is received from a
-		terminal during startup, use |--cmd|: >
-			vim --cmd "call ch_logfile('logfile', 'w')"
+		terminal during startup, use |--log|: >
+			vim --log logfile
 <
 		This function is not available in the |sandbox|.
 		NOTE: the channel communication is stored in the file, be
diff --git a/runtime/doc/starting.txt b/runtime/doc/starting.txt
index 1600441..9a4014b 100644
--- a/runtime/doc/starting.txt
+++ b/runtime/doc/starting.txt
@@ -344,6 +344,12 @@
 		Example: >
 			vim -V20vimlog foobar
 <
+--log {filename}					*--log*
+		Start logging and write entries to {filename}.
+		This works like calling `ch_logfile({filename}, 'a')` very
+		early during startup.
+		{only available with the +channel feature}
+
 							*-D*
 -D		Debugging.  Go to debugging mode when executing the first
 		command from a script. |debug-mode|
@@ -564,6 +570,7 @@
 		{scriptout} cannot start with a digit.
 		If you want to record what is typed in a human readable for
 		you can use |ch_logfile()|, It adds "raw key input" lines.
+		Also see |--log|.
 
 							*-W*
 -W {scriptout}	Like -w, but do not append, overwrite an existing file.