1.\" Copyright (c) 1996-1999 Whistle Communications, Inc. 2.\" All rights reserved. 3.\" 4.\" Subject to the following obligations and disclaimer of warranty, use and 5.\" redistribution of this software, in source or object code forms, with or 6.\" without modifications are expressly permitted by Whistle Communications; 7.\" provided, however, that: 8.\" 1. Any and all reproductions of the source or object code must include the 9.\" copyright notice above and the following disclaimer of warranties; and 10.\" 2. No rights are granted, in any manner or form, to use Whistle 11.\" Communications, Inc. trademarks, including the mark "WHISTLE 12.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as 13.\" such appears in the above copyright notice or in the software. 14.\" 15.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 16.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 17.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 18.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 19.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 20.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 21.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 22.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 23.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 24.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 25.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 26.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 27.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 31.\" OF SUCH DAMAGE. 32.\" 33.\" Author: Archie Cobbs <archie@FreeBSD.org> 34.\" 35.\" $FreeBSD: src/share/man/man4/ng_tty.4,v 1.14.2.1 2001/12/21 09:00:51 ru Exp $ 36.\" $DragonFly: src/share/man/man4/ng_tty.4,v 1.4 2006/08/18 01:42:58 swildner Exp $ 37.\" $Whistle: ng_tty.8,v 1.5 1999/01/25 23:46:28 archie Exp $ 38.\" 39.Dd January 19, 1999 40.Dt NG_TTY 4 41.Os 42.Sh NAME 43.Nm ng_tty 44.Nd netgraph node type that is also a line discipline 45.Sh SYNOPSIS 46.In sys/ttycom.h 47.In netgraph/ng_message.h 48.In netgraph/tty/ng_tty.h 49.Sh DESCRIPTION 50The 51.Nm tty 52node type is both a netgraph node type and a line discipline. 53A new node is created when the corresponding line discipline, 54.Dv NETGRAPHDISC , 55is registered on a tty device (see 56.Xr tty 4 ) . 57.Pp 58The node has a single hook called 59.Dv hook . 60Incoming bytes received on the tty device are sent out on this hook, 61and frames received on 62.Dv hook 63are transmitted out on the tty device. 64No modification to the data is performed in either direction. 65While the line discipline is installed on a tty, the normal 66read and write operations are unavailable, returning 67.Er EIO . 68.Pp 69The node supports an optional 70.Dq hot character . 71If set to non-zero, incoming 72data from the tty device is queued until this character is seen. 73This avoids sending lots of mbufs containing a small number of bytes, 74but introduces potentially infinite latency. 75The default hot character is 0x7e, consistent with 76.Dv hook 77being connected to a 78.Xr ng_async 4 79type node. The hot character has no effect on the transmission of data. 80.Pp 81The node will attempt to give itself the same netgraph name as the name 82of the tty device. 83In any case, information about the node is available via the netgraph 84.Xr ioctl 2 85command 86.Dv NGIOCGINFO . 87This command returns a 88.Dv "struct nodeinfo" 89similar to the 90.Dv NGM_NODEINFO 91netgraph control message. 92.Sh HOOKS 93This node type supports the following hooks: 94.Pp 95.Bl -tag -width foobar 96.It Dv hook 97.Xr tty 4 98serial data contained in 99.Dv mbuf 100structures, with arbitrary inter-frame boundaries. 101.El 102.Sh CONTROL MESSAGES 103This node type supports the generic control messages, plus the following: 104.Bl -tag -width foo 105.It Dv NGM_TTY_SET_HOTCHAR 106This command takes an integer argument and sets the hot character 107from the lower 8 bits. A hot character of zero disables queueing, 108so that all received data is forwarded immediately. 109.It Dv NGM_TTY_GET_HOTCHAR 110Returns an integer containing the current hot character in the lower 111eight bits. 112.El 113.Sh SHUTDOWN 114This node shuts down when the corresponding device is closed 115(or the line discipline is uninstalled on the device). 116The 117.Dv NGM_SHUTDOWN 118control message is not valid, and always returns the error 119.Er EOPNOTSUPP . 120.Sh SEE ALSO 121.Xr ioctl 2 , 122.Xr netgraph 4 , 123.Xr ng_async 4 , 124.Xr tty 4 , 125.Xr ngctl 8 126.Sh HISTORY 127The 128.Nm 129node type was implemented in 130.Fx 4.0 . 131.Sh AUTHORS 132.An Archie Cobbs Aq archie@FreeBSD.org 133.Sh BUGS 134The serial driver code also has a notion of a 135.Dq hot character . 136Unfortunately, this value is statically defined in terms of the 137line discipline and cannot be changed. 138Therefore, if a hot character other than 0x7e (the default) is set for the 139.Nm 140node, the node has no way to convey this information to the 141serial driver, and sub-optimal performance may result. 142