97ffdc179c
nmdm(4), ucom(4), and uart(4) PR: 247638 Submitted by: Pau Amma <pauamma@gundo.com> Reported by: 0mp MFC after: 4 weeks Sponsored by: Klara Inc. Event: July 2020 Bugathon
99 lines
2.4 KiB
Groff
99 lines
2.4 KiB
Groff
.\" Copyright (c) 2001
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.\" The FreeBSD Project
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 11, 2020
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.Dt NMDM 4
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.Os
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.Sh NAME
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.Nm nmdm
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.Nd nullmodem terminal driver
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following line in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device nmdm"
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.Ed
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.Pp
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Alternatively, to load the driver as a
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module at boot time, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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nmdm_load="YES"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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driver provides two
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.Xr tty 4
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devices connected
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by a virtual
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.Dq "null modem"
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cable.
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.Pp
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If either of the two tty devices have the
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.Dv CDSR_OFLOW
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bit
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.Pq Dq Li "stty dsrflow"
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set in their line discipline, the
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.Nm
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device will emulate the speed configured in the
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.Xr termios 4
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settings.
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The speed emulation works independently in the two directions,
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controlled by the slower end's termios settings
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.Va ( c_ispeed , c_ospeed ,
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.Dv CS5 ... CS8 , CSTOPB
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and
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.Dv PARENB ) .
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.Sh FILES
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.Bl -tag -width ".Pa /dev/nmdm Ns Ar N Ns Op Pa AB" -compact
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.It Pa /dev/nmdm Ns Ar N Ns Op Pa AB
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nullmodem device nodes.
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Where the
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.Pa A
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node has a matching
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.Pa B
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node.
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.El
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.Pp
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The
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.Nm
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driver implements
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.Dq "on-demand device creation"
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so simply accessing a given instance in
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.Pa /dev
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will create it.
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.Sh DIAGNOSTICS
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None.
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.Sh SEE ALSO
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.Xr stty 1 ,
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.Xr termios 4 ,
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.Xr tty 4 ,
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.Xr ttys 5
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 4.4 .
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