1.\"-
2.\" Copyright (c) 2001 Miodrag Vallat.
3.\" Copyright (c) 2005 Marius Strobl <marius@FreeBSD.org>
4.\" All rights reserved.
5.\"
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7.\" modification, are permitted provided that the following conditions
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15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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26.\"	from: OpenBSD: pcons.4,v 1.4 2003/06/02 16:16:26 miod Exp
27.\" $FreeBSD$
28.\"
29.Dd January 16, 2021
30.Dt OFW_CONSOLE 4 powerpc
31.Os
32.Sh NAME
33.Nm ofw_console
34.Nd "Open Firmware console"
35.Sh SYNOPSIS
36.Cd "cpu AIM"
37.Cd "options OFWCONS_POLL_HZ=N"
38.Pp
39.Cd "options KDB"
40.Cd "options DDB"
41.Cd "options ALT_BREAK_TO_DEBUGGER"
42.Sh DESCRIPTION
43The
44.Nm
45driver provides a simple text console,
46using the Open Firmware services for input and output.
47It will use the Open Firmware console devices set via the
48.Va input-device
49and
50.Va output-device
51variables.
52.Pp
53This driver is deprecated and only provided as a fallback console mechanism
54if the real console hardware can not be driven by
55.Fx .
56.Pp
57In case the
58.Nm
59console appears to work too slowly, its responsiveness probably can be improved
60by including
61.Cd "options OFWCONS_POLL_HZ=N" .
62When omitted,
63.Dv OFWCONS_POLL_HZ
64defaults to 4.
65For example, on
66.Tn Sun Ultra 2
67a value of 20 or higher works best.
68Too high values, on the other hand, can cause
69.Nm
70to unnecessarily consume CPU.
71.Sh FILES
72.Bl -tag -width ".Pa /dev/keyboard" -compact
73.It Pa /dev/console
74.It Pa /dev/keyboard
75terminal input device in case the console input device is the keyboard
76.It Pa /dev/screen
77terminal output device in case the console output device is the screen
78.It Pa /dev/tty[a-z]
79terminal device in case both the console input and output device is tty[a-z]
80.El
81.Sh SEE ALSO
82.Xr akbd 4 ,
83.Xr powermac_nvram 4 ,
84.Xr vt 4
85.Sh HISTORY
86The
87.Nm
88driver first appeared in
89.Fx 5.0 .
90.Sh AUTHORS
91The
92.Nm
93driver was written by
94.An Benno Rice Aq Mt benno@FreeBSD.org .
95.Sh CAVEATS
96Since the Open Firmware will handle BREAK
97(or Stop-A)
98sequences before
99.Nm ,
100the preferred way to enter
101.Xr ddb 4
102when using
103.Nm
104is to include
105.Cd "options ALT_BREAK_TO_DEBUGGER"
106in a ddb-enabled kernel, and enter the alternate BREAK sequence
107(RETURN TILDE CTRL-b).
108.Sh BUGS
109The
110.Nm
111driver also not attach to the hardware resources it actually talks to.
112