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@@ -1,15 +1,19 @@
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- Linux Serial Console
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+Linux Serial Console
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+====================
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To use a serial port as console you need to compile the support into your
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kernel - by default it is not compiled in. For PC style serial ports
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-it's the config option next to "Standard/generic (dumb) serial support".
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+it's the config option next to menu option:
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+
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+:menuselection:`Character devices --> Serial drivers --> 8250/16550 and compatible serial support --> Console on 8250/16550 and compatible serial port`
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+
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You must compile serial support into the kernel and not as a module.
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It is possible to specify multiple devices for console output. You can
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define a new kernel command line option to select which device(s) to
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use for console output.
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-The format of this option is:
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+The format of this option is::
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console=device,options
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@@ -28,11 +32,11 @@ The format of this option is:
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You can specify multiple console= options on the kernel command line.
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Output will appear on all of them. The last device will be used when
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-you open /dev/console. So, for example:
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+you open ``/dev/console``. So, for example::
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console=ttyS1,9600 console=tty0
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-defines that opening /dev/console will get you the current foreground
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+defines that opening ``/dev/console`` will get you the current foreground
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virtual console, and kernel messages will appear on both the VGA
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console and the 2nd serial port (ttyS1 or COM2) at 9600 baud.
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@@ -44,61 +48,61 @@ first looks for a VGA card and then for a serial port. So if you don't
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have a VGA card in your system the first serial port will automatically
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become the console.
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-You will need to create a new device to use /dev/console. The official
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-/dev/console is now character device 5,1.
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+You will need to create a new device to use ``/dev/console``. The official
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+``/dev/console`` is now character device 5,1.
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(You can also use a network device as a console. See
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-Documentation/networking/netconsole.txt for information on that.)
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+``Documentation/networking/netconsole.txt`` for information on that.)
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-Here's an example that will use /dev/ttyS1 (COM2) as the console.
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+Here's an example that will use ``/dev/ttyS1`` (COM2) as the console.
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Replace the sample values as needed.
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-1. Create /dev/console (real console) and /dev/tty0 (master virtual
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- console):
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+1. Create ``/dev/console`` (real console) and ``/dev/tty0`` (master virtual
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+ console)::
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- cd /dev
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- rm -f console tty0
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- mknod -m 622 console c 5 1
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- mknod -m 622 tty0 c 4 0
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+ cd /dev
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+ rm -f console tty0
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+ mknod -m 622 console c 5 1
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+ mknod -m 622 tty0 c 4 0
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2. LILO can also take input from a serial device. This is a very
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useful option. To tell LILO to use the serial port:
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- In lilo.conf (global section):
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+ In lilo.conf (global section)::
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- serial = 1,9600n8 (ttyS1, 9600 bd, no parity, 8 bits)
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+ serial = 1,9600n8 (ttyS1, 9600 bd, no parity, 8 bits)
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3. Adjust to kernel flags for the new kernel,
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- again in lilo.conf (kernel section)
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+ again in lilo.conf (kernel section)::
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- append = "console=ttyS1,9600"
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+ append = "console=ttyS1,9600"
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4. Make sure a getty runs on the serial port so that you can login to
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it once the system is done booting. This is done by adding a line
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- like this to /etc/inittab (exact syntax depends on your getty):
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+ like this to ``/etc/inittab`` (exact syntax depends on your getty)::
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- S1:23:respawn:/sbin/getty -L ttyS1 9600 vt100
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+ S1:23:respawn:/sbin/getty -L ttyS1 9600 vt100
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-5. Init and /etc/ioctl.save
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+5. Init and ``/etc/ioctl.save``
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- Sysvinit remembers its stty settings in a file in /etc, called
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- `/etc/ioctl.save'. REMOVE THIS FILE before using the serial
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+ Sysvinit remembers its stty settings in a file in ``/etc``, called
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+ ``/etc/ioctl.save``. REMOVE THIS FILE before using the serial
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console for the first time, because otherwise init will probably
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set the baudrate to 38400 (baudrate of the virtual console).
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-6. /dev/console and X
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+6. ``/dev/console`` and X
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Programs that want to do something with the virtual console usually
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- open /dev/console. If you have created the new /dev/console device,
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+ open ``/dev/console``. If you have created the new ``/dev/console`` device,
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and your console is NOT the virtual console some programs will fail.
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Those are programs that want to access the VT interface, and use
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- /dev/console instead of /dev/tty0. Some of those programs are:
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+ ``/dev/console instead of /dev/tty0``. Some of those programs are::
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- Xfree86, svgalib, gpm, SVGATextMode
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+ Xfree86, svgalib, gpm, SVGATextMode
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It should be fixed in modern versions of these programs though.
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- Note that if you boot without a console= option (or with
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- console=/dev/tty0), /dev/console is the same as /dev/tty0. In that
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- case everything will still work.
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+ Note that if you boot without a ``console=`` option (or with
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+ ``console=/dev/tty0``), ``/dev/console`` is the same as ``/dev/tty0``.
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+ In that case everything will still work.
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7. Thanks
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