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[PATCH] doc: more serial-console info

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

Signed-off-by: Randy Dunlap <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>
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1 parent 174e27c commit f1a1c2dc2a956c375b432d2a9a28e52ba9d81c7c Randy Dunlap committed with Linus Torvalds Mar 25, 2006
Showing with 18 additions and 8 deletions.
  1. +10 −5 Documentation/kernel-parameters.txt
  2. +8 −3 Documentation/serial-console.txt
@@ -367,12 +367,17 @@ running once the system is up.
tty<n> Use the virtual console device <n>.
+ 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.
@@ -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.

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