b11fd9c5ab
(LSB is 0). The iic(4) manpage probably needs similar language to describe the format it expects.
206 lines
5.2 KiB
Groff
206 lines
5.2 KiB
Groff
.\" Copyright (c) 1998, Nicolas Souchu
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.\" Copyright (c) 2004, Joerg Wunsch
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 6, 2009
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.Dt SMB 4
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.Os
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.Sh NAME
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.Nm smb
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.Nd SMB generic I/O device driver
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.Sh SYNOPSIS
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.Cd "device smb"
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.Sh DESCRIPTION
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The
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.Em smb
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character device driver provides generic i/o to any
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.Xr smbus 4
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instance.
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In order to control SMB devices, use
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.Pa /dev/smb?
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with the ioctls described below.
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Any of these ioctl commands takes a pointer to
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.Vt struct smbcmd
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as its argument.
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.Pp
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.Bd -literal
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#include <sys/types.h>
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struct smbcmd {
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char cmd;
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int count;
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u_char slave;
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union {
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char byte;
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short word;
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char *byte_ptr;
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short *word_ptr;
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struct {
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short sdata;
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short *rdata;
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} process;
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} data;
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};
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.Ed
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.Pp
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The
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.Fa slave
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field is always used, and provides the address of the
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SMBus slave device to talk to.
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The slave address is specified in the seven most significant bits
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.Pq i.e. Dq "left-justified" .
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The least significant bit of the slave address must be zero.
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.Pp
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.Bl -column ".Dv SMB_QUICK_WRITE" -compact
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.It Em Ioctl Ta Em Description
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.Pp
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.It Dv SMB_QUICK_WRITE Ta
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The
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.Em QuickWrite
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command just issues the device address with write intent
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to the bus, without transferring any data.
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.It Dv SMB_QUICK_READ Ta
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The
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.Em QuickRead
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command just issues the device address with read intent
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to the bus, without transferring any data.
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.It Dv SMB_SENDB Ta
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The
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.Em SendByte
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command sends the byte provided in the
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.Fa cmd
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field to the device.
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.It Dv SMB_RECVB Ta
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The
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.Em ReceiveByte
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command reads a single byte from the device which will
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be returned in the
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.Fa cmd
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field.
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.It Dv SMB_WRITEB Ta
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The
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.Em WriteByte
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command first sends the byte from the
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.Fa cmd
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field to the device, followed by the byte given in
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.Fa data.byte .
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.It Dv SMB_WRITEW Ta
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The
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.Em WriteWord
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command first sends the byte from the
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.Fa cmd
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field to the device, followed by the word given in
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.Fa data.word .
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Note that the SMBus byte-order is little-endian by definition.
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.It Dv SMB_READB Ta
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The
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.Em ReadByte
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command first sends the byte from the
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.Fa cmd
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field to the device, and then reads one byte of data from
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the device.
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The returned data will be stored in the location pointed to by
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.Fa data.byte_ptr .
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.It Dv SMB_READW Ta
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The
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.Em ReadWord
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command first sends the byte from the
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.Fa cmd
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field to the device, and then reads one word of data from
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the device.
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The returned data will be stored in the location pointed to by
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.Fa data.word_ptr .
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.It Dv SMB_PCALL Ta
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The
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.Em ProcedureCall
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command first sends the byte from the
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.Fa cmd
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field to the device, followed by the word provided in
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.Fa data.process.sdata .
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It then reads one word of data from the device, and returns it
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in the location pointed to by
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.Fa data.process.rdata .
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.It Dv SMB_BWRITE Ta
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The
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.Em BlockWrite
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command first sends the byte from the
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.Fa cmd
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field to the device, followed by
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.Fa count
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bytes of data that are taken from the buffer pointed to by
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.Fa data.byte_ptr .
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The SMBus specification mandates that no more than 32 bytes of
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data can be transferred in a single block read or write command.
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This value is available in the constant
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.Dv SMB_MAXBLOCKSIZE .
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.It Dv SMB_BREAD Ta
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The
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.Em BlockRead
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command first sends the byte from the
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.Fa cmd
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field to the device, and then reads
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.Fa count
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bytes of data that from the device.
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These data will be returned in the buffer pointed to by
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.Fa data.byte_ptr .
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.El
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.Pp
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The
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.Xr read 2
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and
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.Xr write 2
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system calls are not implemented by this driver.
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.Sh ERRORS
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The
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.Xr ioctl 2
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commands can cause the following driver-specific errors:
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.Bl -tag -width Er
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.It Bq Er ENXIO
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Device did not respond to selection.
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.It Bq Er EBUSY
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Device still in use.
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.It Bq Er ENODEV
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Operation not supported by device (not supposed to happen).
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.It Bq Er EINVAL
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General argument error.
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.It Bq Er EWOULDBLOCK
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SMBus transaction timed out.
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.El
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.Sh SEE ALSO
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.Xr ioctl 2 ,
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.Xr smbus 4
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.Sh HISTORY
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The
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.Nm
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manual page first appeared in
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.Fx 3.0 .
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.Sh AUTHORS
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This
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manual page was written by
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.An Nicolas Souchu .
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