.\"-
.\" Copyright (c) 2001 Miodrag Vallat.
.\" Copyright (c) 2005 Marius Strobl <marius@FreeBSD.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistribution of source code must retain the above copyright
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.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
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.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\"	from: OpenBSD: pcons.4,v 1.4 2003/06/02 16:16:26 miod Exp
.\" $FreeBSD$
.\"
.Dd June 18, 2005
.Dt OFW_CONSOLE 4 sparc64
.Os
.Sh NAME
.Nm ofw_console
.Nd "Open Firmware console"
.Sh SYNOPSIS
.Cd "device ofw_console"
.Cd "options OFWCONS_POLL_HZ=N"
.Pp
.Cd "options KDB"
.Cd "options DDB"
.Cd "options ALT_BREAK_TO_DEBUGGER"
.Sh DESCRIPTION
The
.Nm
driver provides a simple text console,
using the Open Firmware services for input and output.
It will use the Open Firmware console devices set via the
.Va input-device
and
.Va output-device
variables.
.Pp
This driver is deprecated and only provided as a fallback console mechanism
if the real console hardware can not be driven by
.Fx .
.Pp
In case the
.Nm
console appears to work too slowly, its responsiveness probably can be improved
by including
.Cd "options OFWCONS_POLL_HZ=N" .
When omitted,
.Dv OFWCONS_POLL_HZ
defaults to 4.
For example, on
.Tn Sun Ultra 2
a value of 20 or higher works best.
Too high values, on the other hand, can cause
.Nm
to unnecessarily consume CPU.
.Sh FILES
.Bl -tag -width ".Pa /dev/keyboard" -compact
.It Pa /dev/console
.It Pa /dev/keyboard
terminal input device in case the console input device is the keyboard
.It Pa /dev/screen
terminal output device in case the console output device is the screen
.It Pa /dev/tty[a-z]
terminal device in case both the console input and output device is tty[a-z]
.El
.Sh SEE ALSO
.Xr creator 4 ,
.Xr machfb 4 ,
.Xr syscons 4 ,
.Xr uart 4 ,
.Xr eeprom 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 5.0 .
.Sh AUTHORS
The
.Nm
driver was written by
.An Benno Rice Aq Mt benno@FreeBSD.org .
.Sh CAVEATS
Since the Open Firmware will handle BREAK
(or Stop-A)
sequences before
.Nm ,
the preferred way to enter
.Xr ddb 4
when using
.Nm
is to include
.Cd "options ALT_BREAK_TO_DEBUGGER"
in a ddb-enabled kernel, and enter the alternate BREAK sequence
(RETURN TILDE CTRL-b).
.Sh BUGS
The
.Nm
driver
is not a real
.Xr tty 4
driver and is not MPSAFE.
The
.Nm
driver also does not attach to the hardware resources it actually talks to.
Therefore it cannot be included in the kernel together with real console
hardware drivers
like
.Xr creator 4 ,
.Xr machfb 4
and
.Xr uart 4 .