Commit c2ffd5da authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab

Documentation/serial-console.txt: convert it to ReST markup

- Fix identation for the document title;
- use monotonic fonts for paths;
- use quote blocks where needed;
- adjust spaces to properly format paragraphs;
- use :menuselection: for the menu item;
- add it to the user book.
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent 5902981b
Linux Serial Console
Linux Serial Console
====================
To use a serial port as console you need to compile the support into your
kernel - by default it is not compiled in. For PC style serial ports
it's the config option next to "Standard/generic (dumb) serial support".
it's the config option next to menu option:
:menuselection:`Character devices --> Serial drivers --> 8250/16550 and compatible serial support --> Console on 8250/16550 and compatible serial port`
You must compile serial support into the kernel and not as a module.
It is possible to specify multiple devices for console output. You can
define a new kernel command line option to select which device(s) to
use for console output.
The format of this option is:
The format of this option is::
console=device,options
......@@ -28,11 +32,11 @@ The format of this option is:
You can specify multiple console= options on the kernel command line.
Output will appear on all of them. The last device will be used when
you open /dev/console. So, for example:
you open ``/dev/console``. So, for example::
console=ttyS1,9600 console=tty0
defines that opening /dev/console will get you the current foreground
defines that opening ``/dev/console`` will get you the current foreground
virtual console, and kernel messages will appear on both the VGA
console and the 2nd serial port (ttyS1 or COM2) at 9600 baud.
......@@ -44,17 +48,17 @@ first looks for a VGA card and then for a serial port. So if you don't
have a VGA card in your system the first serial port will automatically
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 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.)
``Documentation/networking/netconsole.txt`` for information on that.)
Here's an example that will use /dev/ttyS1 (COM2) as the console.
Here's an example that will use ``/dev/ttyS1`` (COM2) as the console.
Replace the sample values as needed.
1. Create /dev/console (real console) and /dev/tty0 (master virtual
console):
1. Create ``/dev/console`` (real console) and ``/dev/tty0`` (master virtual
console)::
cd /dev
rm -f console tty0
......@@ -63,42 +67,42 @@ Replace the sample values as needed.
2. LILO can also take input from a serial device. This is a very
useful option. To tell LILO to use the serial port:
In lilo.conf (global section):
In lilo.conf (global section)::
serial = 1,9600n8 (ttyS1, 9600 bd, no parity, 8 bits)
3. Adjust to kernel flags for the new kernel,
again in lilo.conf (kernel section)
again in lilo.conf (kernel section)::
append = "console=ttyS1,9600"
4. Make sure a getty runs on the serial port so that you can login to
it once the system is done booting. This is done by adding a line
like this to /etc/inittab (exact syntax depends on your getty):
like this to ``/etc/inittab`` (exact syntax depends on your getty)::
S1:23:respawn:/sbin/getty -L ttyS1 9600 vt100
5. Init and /etc/ioctl.save
5. Init and ``/etc/ioctl.save``
Sysvinit remembers its stty settings in a file in /etc, called
`/etc/ioctl.save'. REMOVE THIS FILE before using the serial
Sysvinit remembers its stty settings in a file in ``/etc``, called
``/etc/ioctl.save``. REMOVE THIS FILE before using the serial
console for the first time, because otherwise init will probably
set the baudrate to 38400 (baudrate of the virtual console).
6. /dev/console and X
6. ``/dev/console`` and X
Programs that want to do something with the virtual console usually
open /dev/console. If you have created the new /dev/console device,
open ``/dev/console``. If you have created the new ``/dev/console`` device,
and your console is NOT the virtual console some programs will fail.
Those are programs that want to access the VT interface, and use
/dev/console instead of /dev/tty0. Some of those programs are:
``/dev/console instead of /dev/tty0``. Some of those programs are::
Xfree86, svgalib, gpm, SVGATextMode
It should be fixed in modern versions of these programs though.
Note that if you boot without a console= option (or with
console=/dev/tty0), /dev/console is the same as /dev/tty0. In that
case everything will still work.
Note that if you boot without a ``console=`` option (or with
``console=/dev/tty0``), ``/dev/console`` is the same as ``/dev/tty0``.
In that case everything will still work.
7. Thanks
......
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