mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-20 11:11:24 +00:00
143 lines
5.0 KiB
Groff
143 lines
5.0 KiB
Groff
.\" Copyright (c) 1996-1999 Whistle Communications, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Subject to the following obligations and disclaimer of warranty, use and
|
|
.\" redistribution of this software, in source or object code forms, with or
|
|
.\" without modifications are expressly permitted by Whistle Communications;
|
|
.\" provided, however, that:
|
|
.\" 1. Any and all reproductions of the source or object code must include the
|
|
.\" copyright notice above and the following disclaimer of warranties; and
|
|
.\" 2. No rights are granted, in any manner or form, to use Whistle
|
|
.\" Communications, Inc. trademarks, including the mark "WHISTLE
|
|
.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as
|
|
.\" such appears in the above copyright notice or in the software.
|
|
.\"
|
|
.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
|
|
.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
|
|
.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
|
|
.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
|
|
.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
|
|
.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
|
|
.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
|
|
.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
|
|
.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
|
|
.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
|
|
.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
|
|
.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
|
|
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
|
|
.\" OF SUCH DAMAGE.
|
|
.\"
|
|
.\" Author: Archie Cobbs <archie@FreeBSD.org>
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\" $Whistle: ng_tty.8,v 1.5 1999/01/25 23:46:28 archie Exp $
|
|
.\"
|
|
.Dd January 19, 1999
|
|
.Dt NG_TTY 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ng_tty
|
|
.Nd netgraph node type that is also a line discipline
|
|
.Sh SYNOPSIS
|
|
.In sys/types.h
|
|
.In sys/ttycom.h
|
|
.In netgraph/ng_tty.h
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm tty
|
|
node type is both a netgraph node type and a line discipline.
|
|
A new node is created when the corresponding line discipline,
|
|
.Dv NETGRAPHDISC ,
|
|
is registered on a tty device (see
|
|
.Xr tty 4 ) .
|
|
.Pp
|
|
The node has a single hook called
|
|
.Dv hook .
|
|
Incoming bytes received on the tty device are sent out on this hook,
|
|
and frames received on
|
|
.Dv hook
|
|
are transmitted out on the tty device.
|
|
No modification to the data is performed in either direction.
|
|
While the line discipline is installed on a tty, the normal
|
|
read and write operations are unavailable, returning
|
|
.Er EIO .
|
|
.Pp
|
|
The node supports an optional
|
|
.Dq hot character .
|
|
If set to non-zero, incoming
|
|
data from the tty device is queued until this character is seen.
|
|
This avoids sending lots of mbufs containing a small number of bytes,
|
|
but introduces potentially infinite latency.
|
|
The default hot character is 0x7e, consistent with
|
|
.Dv hook
|
|
being connected to a
|
|
.Xr ng_async 4
|
|
type node.
|
|
The hot character has no effect on the transmission of data.
|
|
.Pp
|
|
The node will attempt to give itself the same netgraph name as the name
|
|
of the tty device.
|
|
In any case, information about the node is available via the netgraph
|
|
.Xr ioctl 2
|
|
command
|
|
.Dv NGIOCGINFO .
|
|
This command returns a
|
|
.Dv "struct nodeinfo"
|
|
similar to the
|
|
.Dv NGM_NODEINFO
|
|
netgraph control message.
|
|
.Sh HOOKS
|
|
This node type supports the following hooks:
|
|
.Pp
|
|
.Bl -tag -width foobar
|
|
.It Dv hook
|
|
.Xr tty 4
|
|
serial data contained in
|
|
.Dv mbuf
|
|
structures, with arbitrary inter-frame boundaries.
|
|
.El
|
|
.Sh CONTROL MESSAGES
|
|
This node type supports the generic control messages, plus the following:
|
|
.Bl -tag -width foo
|
|
.It Dv NGM_TTY_SET_HOTCHAR
|
|
This command takes an integer argument and sets the hot character
|
|
from the lower 8 bits.
|
|
A hot character of zero disables queueing,
|
|
so that all received data is forwarded immediately.
|
|
.It Dv NGM_TTY_GET_HOTCHAR
|
|
Returns an integer containing the current hot character in the lower
|
|
eight bits.
|
|
.El
|
|
.Sh SHUTDOWN
|
|
This node shuts down when the corresponding device is closed
|
|
(or the line discipline is uninstalled on the device).
|
|
The
|
|
.Dv NGM_SHUTDOWN
|
|
control message is not valid, and always returns the error
|
|
.Er EOPNOTSUPP .
|
|
.Sh SEE ALSO
|
|
.Xr ioctl 2 ,
|
|
.Xr netgraph 4 ,
|
|
.Xr ng_async 4 ,
|
|
.Xr tty 4 ,
|
|
.Xr ngctl 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
node type was implemented in
|
|
.Fx 4.0 .
|
|
.Sh AUTHORS
|
|
.An Archie Cobbs Aq archie@FreeBSD.org
|
|
.Sh BUGS
|
|
The serial driver code also has a notion of a
|
|
.Dq hot character .
|
|
Unfortunately, this value is statically defined in terms of the
|
|
line discipline and cannot be changed.
|
|
Therefore, if a hot character other than 0x7e (the default) is set for the
|
|
.Nm
|
|
node, the node has no way to convey this information to the
|
|
serial driver, and sub-optimal performance may result.
|