Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help 
NMDM(4)			    Kernel Interfaces Manual		       NMDM(4)

NAME
       nmdm -- nullmodem terminal driver

SYNOPSIS
       To  compile  this  driver  into the kernel, place the following line in
       your kernel configuration file:

	     device nmdm

       Alternatively, to load the driver as a module at	boot time,  place  the
       following line in loader.conf(5):

	     nmdm_load="YES"

DESCRIPTION
       The  nmdm  driver  provides  two	 tty(4)	devices	connected by a virtual
       "null modem" cable.

       If either of the	 two  tty  devices  have  the  CDSR_OFLOW  bit	("stty
       dsrflow")  set  in  their line discipline, the nmdm device will emulate
       the speed configured in the termios(4) settings.	 The  speed  emulation
       works  independently  in	 the  two directions, controlled by the	slower
       end's termios settings (c_ispeed, c_ospeed, CS5	...  CS8,  CSTOPB  and
       PARENB).

FILES
       /dev/nmdmN[AB]  nullmodem  device nodes.	 Where the A node has a	match-
		       ing B node.

       The nmdm	driver implements "on-demand device creation"  so  simply  ac-
       cessing a given instance	in /dev	will create it.

DIAGNOSTICS
       None.

SEE ALSO
       stty(1),	termios(4), tty(4), ttys(5)

HISTORY
       The nmdm	driver first appeared in FreeBSD 4.4.

FreeBSD	14.3			 July 11, 2020			       NMDM(4)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=nmdm&manpath=FreeBSD+14.3-RELEASE+and+Ports>

home | help