f1cd40a19d
After removal of SMB_TRANS some information in the description of SMB_BWRITE has become stale. E.g., the maximum block size has been restored to 32. Also, the descriptions of SMB_BREAD and SMB_BWRITE had some incorrect information on the SMBus protocol details. MFC after: 1 week X-MFC with: r308242 Differential Revision: https://reviews.freebsd.org/D8431
201 lines
5.1 KiB
Groff
201 lines
5.1 KiB
Groff
.\" Copyright (c) 1998, Nicolas Souchu
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.\" Copyright (c) 2004, Joerg Wunsch
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.\" Copyright (c) 2015, Michael Gmelin <freebsd@grem.de>
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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 April 25, 2015
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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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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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.Bd -literal
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#include <sys/types.h>
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struct smbcmd {
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u_char cmd;
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u_char reserved;
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u_short op;
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union {
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char byte;
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char buf[2];
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short word;
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} wdata;
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union {
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char byte;
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char buf[2];
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short word;
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} rdata;
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int slave;
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char *wbuf; /* use wdata if NULL */
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int wcount;
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char *rbuf; /* use rdata if NULL */
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int rcount;
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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.
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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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.Em QuickWrite
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does not transfer any data.
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It just issues the device address with write intent to the bus.
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.It Dv SMB_QUICK_READ Ta
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.Em QuickRead
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does not transfer any data.
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It just issues the device address with read intent to the bus.
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.It Dv SMB_SENDB Ta
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.Em SendByte
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sends the byte provided in
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.Fa cmd
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to the device.
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.It Dv SMB_RECVB Ta
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.Em ReceiveByte
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reads a single byte from the device which is returned in
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.Fa cmd .
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.It Dv SMB_WRITEB Ta
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.Em WriteByte
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first sends the byte from
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.Fa cmd
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to the device, followed by the byte given in
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.Fa wdata.byte .
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.It Dv SMB_WRITEW Ta
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.Em WriteWord
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first sends the byte from
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.Fa cmd
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to the device, followed by the word given in
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.Fa wdata.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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.Em ReadByte
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first sends the byte from
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.Fa cmd
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to the device, then reads one byte of data from
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the device.
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Returned data is stored in
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.Fa rdata.byte .
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.It Dv SMB_READW Ta
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.Em ReadWord
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first sends the byte from
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.Fa cmd
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to the device, then reads one word of data from
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the device.
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Returned data is stored in
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.Fa rdata.word .
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.It Dv SMB_PCALL Ta
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.Em ProcedureCall
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first sends the byte from
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.Fa cmd
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to the device, followed by the word provided in
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.Fa wdata.word .
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It then reads one word of data from the device and returns it
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in
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.Fa rdata.word .
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.It Dv SMB_BWRITE Ta
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.Em BlockWrite
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first sends the byte from
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.Fa cmd
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to the device, then the byte from
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.Fa wcount
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followed by
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.Fa wcount
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bytes of data that are taken from the buffer pointed to by
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.Fa wbuf .
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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 can be read from the constant
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.Dv SMB_MAXBLOCKSIZE .
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.It Dv SMB_BREAD Ta
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.Em BlockRead
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first sends the byte from
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.Fa cmd
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to the device, then reads a count of data bytes that the device
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is going to provide and then reads that many bytes.
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The count is returned in
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.Fa rcount.
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The data is returned in the buffer pointed to by
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.Fa rbuf .
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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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and extended by
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.An Michael Gmelin Aq freebsd@grem.de .
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