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$FreeBSD: stable/10/share/man/man4/nmdm.4 328921 2018-02-06 07:50:30Z delphij $
.Dd January 23, 2018 .Dt NMDM 4 .Os .Sh NAME .Nm nmdm .Nd nullmodem terminal driver .Sh SYNOPSIS To compile this driver into the kernel, place the following line in your kernel configuration file: d -ragged -offset indent .Cd "device nmdm" .Ed
p Alternatively, to load the driver as a module at boot time, place the following line in .Xr loader.conf 5 : d -literal -offset indent nmdm_load="YES" .Ed .Sh DESCRIPTION The .Nm driver provides two .Xr tty 4 devices connected by a virtual .Dq "null modem" cable.
p If either of the two tty devices have the .Dv CDSR_OFLOW bit
q Dq Li "stty dsrflow" set in their line discipline, the .Nm device will emulate the speed configured in the .Xr termios 4 settings. The speed emulation works independently in the two directions, controlled by the slower end's termios settings .Va ( c_ispeed , c_ospeed , .Dv CS5 ... CS8 , CSTOPB and .Dv PARENB ) . .Sh FILES l -tag -width ".Pa /dev/nmdm Ns Ar N Ns Op Pa AB" -compact t Pa /dev/nmdm Ns Ar N Ns Op Pa AB nullmodem device nodes. Where the
a A node has a matching
a B node. .El
p The .Nm driver implements .Dq "on-demand device creation" so simply accessing a given instance in
a /dev will create it. .Sh DIAGNOSTICS None. .Sh SEE ALSO .Xr stty 1 , .Xr termios 4 , .Xr tty 4 .Sh HISTORY The .Nm driver first appeared in .Fx 4.4 .