[PATCH] doc: more serial-console info

Add info on flow control for serial consoles.  Refer to netconsole option
also.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/kernel-parameters.txt

@@ -367,12 +367,17 @@ running once the system is up.
 		tty<n>	Use the virtual console device <n>.
 
 		ttyS<n>[,options]
+		ttyUSB0[,options]
 			Use the specified serial port.  The options are of
-			the form "bbbbpn", where "bbbb" is the baud rate,
-			"p" is parity ("n", "o", or "e"), and "n" is bits.
-			Default is "9600n8".
+			the form "bbbbpnf", where "bbbb" is the baud rate,
+			"p" is parity ("n", "o", or "e"), "n" is number of
+			bits, and "f" is flow control ("r" for RTS or
+			omit it).  Default is "9600n8".
 
-			See also Documentation/serial-console.txt.
+			See Documentation/serial-console.txt for more
+			information.  See
+			Documentation/networking/netconsole.txt for an
+			alternative.
 
 		uart,io,<addr>[,options]
 		uart,mmio,<addr>[,options]

Documentation/serial-console.txt

@@ -17,11 +17,13 @@ The format of this option is:
 			ttyX for any other virtual console
 			ttySx for a serial port
 			lp0 for the first parallel port
+			ttyUSB0 for the first USB serial device
 
 	options:	depend on the driver. For the serial port this
-			defines the baudrate/parity/bits of the port,
-			in the format BBBBPN, where BBBB is the speed,
-			P is parity (n/o/e), and N is bits. Default is
+			defines the baudrate/parity/bits/flow control of
+			the port, in the format BBBBPNF, where BBBB is the
+			speed, P is parity (n/o/e), N is number of bits,
+			and F is flow control ('r' for RTS). Default is
 			9600n8. The maximum baudrate is 115200.
 
 You can specify multiple console= options on the kernel command line.
@@ -45,6 +47,9 @@ become the console.
 You will need to create a new device to use /dev/console. The official
 /dev/console is now character device 5,1.
 
+(You can also use a network device as a console.  See
+Documentation/networking/netconsole.txt for information on that.)
+
 Here's an example that will use /dev/ttyS1 (COM2) as the console.
 Replace the sample values as needed.