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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.\" $Whistle: ng_tty.8,v 1.5 1999/01/25 23:46:28 archie Exp $ 37.\" 38.Dd January 19, 1999 39.Dt NG_TTY 4 40.Os 41.Sh NAME 42.Nm ng_tty 43.Nd netgraph node type that is also a line discipline 44.Sh SYNOPSIS 45.In sys/ttycom.h 46.In netgraph/ng_message.h 47.In netgraph/tty/ng_tty.h 48.Sh DESCRIPTION 49The 50.Nm tty 51node type is both a netgraph node type and a line discipline. 52A new node is created when the corresponding line discipline, 53.Dv NETGRAPHDISC , 54is registered on a tty device (see 55.Xr tty 4 ) . 56.Pp 57The node has a single hook called 58.Dv hook . 59Incoming bytes received on the tty device are sent out on this hook, 60and frames received on 61.Dv hook 62are transmitted out on the tty device. 63No modification to the data is performed in either direction. 64While the line discipline is installed on a tty, the normal 65read and write operations are unavailable, returning 66.Er EIO . 67.Pp 68The node supports an optional 69.Dq hot character . 70If set to non-zero, incoming 71data from the tty device is queued until this character is seen. 72This avoids sending lots of mbufs containing a small number of bytes, 73but introduces potentially infinite latency. 74The default hot character is 0x7e, consistent with 75.Dv hook 76being connected to a 77.Xr ng_async 4 78type node. The hot character has no effect on the transmission of data. 79.Pp 80The node will attempt to give itself the same netgraph name as the name 81of the tty device. 82In any case, information about the node is available via the netgraph 83.Xr ioctl 2 84command 85.Dv NGIOCGINFO . 86This command returns a 87.Dv "struct nodeinfo" 88similar to the 89.Dv NGM_NODEINFO 90netgraph control message. 91.Sh HOOKS 92This node type supports the following hooks: 93.Bl -tag -width foobar 94.It Dv hook 95.Xr tty 4 96serial data contained in 97.Dv mbuf 98structures, with arbitrary inter-frame boundaries. 99.El 100.Sh CONTROL MESSAGES 101This node type supports the generic control messages, plus the following: 102.Bl -tag -width foo 103.It Dv NGM_TTY_SET_HOTCHAR 104This command takes an integer argument and sets the hot character 105from the lower 8 bits. A hot character of zero disables queueing, 106so that all received data is forwarded immediately. 107.It Dv NGM_TTY_GET_HOTCHAR 108Returns an integer containing the current hot character in the lower 109eight bits. 110.El 111.Sh SHUTDOWN 112This node shuts down when the corresponding device is closed 113(or the line discipline is uninstalled on the device). 114The 115.Dv NGM_SHUTDOWN 116control message is not valid, and always returns the error 117.Er EOPNOTSUPP . 118.Sh SEE ALSO 119.Xr ioctl 2 , 120.Xr netgraph 4 , 121.Xr ng_async 4 , 122.Xr tty 4 , 123.Xr ngctl 8 124.Sh HISTORY 125The 126.Nm 127node type was implemented in 128.Fx 4.0 . 129.Sh AUTHORS 130.An Archie Cobbs Aq Mt archie@FreeBSD.org 131.Sh BUGS 132The serial driver code also has a notion of a 133.Dq hot character . 134Unfortunately, this value is statically defined in terms of the 135line discipline and cannot be changed. 136Therefore, if a hot character other than 0x7e (the default) is set for the 137.Nm 138node, the node has no way to convey this information to the 139serial driver, and sub-optimal performance may result. 140