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.\" $FreeBSD$ 36.\" $Whistle: ng_tty.8,v 1.5 1999/01/25 23:46:28 archie Exp $ 37.\" 38.Dd December 25, 2008 39.Dt NG_TTY 4 40.Os 41.Sh NAME 42.Nm ng_tty 43.Nd netgraph node type that is also a TTY hook 44.Sh SYNOPSIS 45.In sys/types.h 46.In sys/ttycom.h 47.In netgraph/ng_tty.h 48.Sh DESCRIPTION 49The 50.Nm tty 51node type is both a netgraph node type and a TTY hook. 52.Pp 53The node has a single hook called 54.Dv hook . 55Incoming bytes received on the tty device are sent out on this hook, 56and frames received on 57.Dv hook 58are transmitted out on the tty device. 59No modification to the data is performed in either direction. 60While the hook is installed on a tty, the normal read and write 61operations are unavailable, returning 62.Er EIO . 63.Pp 64Incoming data is delivered directly to ng_tty via the tty bypass hook as a 65buffer pointer and length, this is converted to a mbuf and passed to the peer. 66.Pp 67The node supports an optional 68.Dq hot character . 69If the driver can not deliver data directly to the tty bypass hook then each 70character is input one at a time. 71If set to non-zero and bypass mode is unavailable, 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. 80The hot character has no effect on the transmission of data. 81.Sh HOOKS 82This node type supports the following hooks: 83.Bl -tag -width ".Va hook" 84.It Va hook 85.Xr tty 4 86serial data contained in 87.Dv mbuf 88structures, with arbitrary inter-frame boundaries. 89.El 90.Sh CONTROL MESSAGES 91This node type supports the generic control messages, plus the following: 92.Bl -tag -width foo 93.It Dv NGM_TTY_SET_HOTCHAR 94This command takes an integer argument and sets the hot character 95from the lower 8 bits. 96A hot character of zero disables queueing, 97so that all received data is forwarded immediately. 98.It Dv NGM_TTY_GET_HOTCHAR 99Returns an integer containing the current hot character in the lower 100eight bits. 101.It Dv NGM_TTY_SET_TTY 102This command takes integer process ID and file descriptor of open tty 103and registers the tty hooks. 104.El 105.Sh SHUTDOWN 106This node shuts down when the corresponding device is closed. 107.Sh SEE ALSO 108.Xr ioctl 2 , 109.Xr netgraph 4 , 110.Xr ng_async 4 , 111.Xr tty 4 , 112.Xr ngctl 8 113.Sh HISTORY 114The 115.Nm 116node type was implemented in 117.Fx 4.0 . 118.Sh AUTHORS 119.An Archie Cobbs Aq Mt archie@FreeBSD.org 120.An Andrew Thompson Aq Mt thompsa@FreeBSD.org 121.Sh BUGS 122The serial driver code also has a notion of a 123.Dq hot character . 124Unfortunately, this value is statically defined in terms of the 125line discipline and cannot be changed. 126Therefore, if a hot character other than 0x7e (the default) is set for the 127.Nm 128node, the node has no way to convey this information to the 129serial driver, and sub-optimal performance may result. 130