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