[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>

2 files changed, 18 insertions, 8 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 44a25f3f51d1..f8cb55c30b0f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/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".
-
-                        See also Documentation/serial-console.txt.
+                        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 Documentation/serial-console.txt for more
+                        information.  See
+                        Documentation/networking/netconsole.txt for an
+                        alternative.
 
                 uart,io,<addr>[,options]
                 uart,mmio,<addr>[,options]
diff --git a/Documentation/serial-console.txt b/Documentation/serial-console.txt
index 6c689b0df2b8..9a7bc8b3f479 100644
--- a/Documentation/serial-console.txt
+++ b/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.