153 lines
4.0 KiB
Groff
153 lines
4.0 KiB
Groff
.\" Copyright (c) 2002
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.\" Nate Lawson. 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. Neither the name of the author nor the names of any co-contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY Nate Lawson 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 December 13, 2011
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.Dt TARG 4
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.Os
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.Sh NAME
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.Nm targ
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.Nd SCSI target emulator driver
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following line in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device targ"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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driver provides an interface for usermode programs to emulate SCSI target
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devices.
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A sample program that emulates a disk drive (similar to
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.Xr da 4 )
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can be found in
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.Pa /usr/share/examples/scsi_target .
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.Pp
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The
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.Nm
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driver supplies the control device
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.Pa /dev/targ .
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After opening the device, the file descriptor must be bound to a
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specific bus/target/LUN and enabled to process CCBs using the
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.Dv TARGIOCENABLE
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ioctl.
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The process then uses
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.Xr write 2
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to send CCBs to the SIM and
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.Xr poll 2
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or
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.Xr kqueue 2
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to see if responses are ready.
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Pointers to completed CCBs are returned via
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.Xr read 2 .
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Any data transfers requested by the user CCBs are done via zero-copy IO.
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.Sh IOCTLS
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The following
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.Xr ioctl 2
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calls are defined in the header file
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.In cam/scsi/scsi_targetio.h .
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.Bl -tag -width ".Dv TARGIOCDISABLE"
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.It Dv TARGIOCENABLE
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.Pq Vt "struct ioc_enable_lun"
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Enable target mode on the LUN specified by the following structure:
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.Bd -literal -offset indent
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struct ioc_enable_lun {
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path_id_t path_id;
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target_id_t target_id;
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lun_id_t lun_id;
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int grp6_len;
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int grp7_len;
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};
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.Ed
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.Pp
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The selected path (bus), target, and LUN must not already be in use or
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.Er EADDRINUSE
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is returned.
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If
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.Va grp6_len
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or
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.Va grp7_len
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are non-zero, reception of vendor-specific commands
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is enabled.
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.It Dv TARGIOCDISABLE
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Disable target mode and abort all pending CCBs.
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The CCBs may optionally be read as they complete.
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.Dv TARGIOCENABLE
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can then be called to activate a different LUN.
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Multiple disable calls have no effect.
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The
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.Xr close 2
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system call automatically disables target mode if enabled.
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.It Dv TARGIOCDEBUG
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.Pq Vt int
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Enables
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.Dv CAM_PERIPH
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debugging if the argument is non-zero, otherwise disables
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it.
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.El
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.Sh FILES
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.Bl -tag -width ".Pa /sys/cam/scsi/scsi_target.c" -compact
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.It In cam/scsi/scsi_targetio.h
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describes the usermode interface.
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.It Pa /sys/cam/scsi/scsi_target.c
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is the driver source file.
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.It Pa /dev/targ
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is the control device.
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.El
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.Sh SEE ALSO
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.Pa /usr/share/examples/scsi_target ,
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.Xr ahc 4 ,
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.Xr isp 4 ,
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.Xr scsi 4
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.Rs
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.%T "FreeBSD Target Information"
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.%U http://www.root.org/~nate/freebsd/
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.Re
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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driver first appeared in
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.Fx 3.0
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and was written by
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.An Justin T. Gibbs .
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It was rewritten
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for
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.Fx 5.0
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by
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.An Nate Lawson Aq Mt nate@root.org .
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.Sh BUGS
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Currently, only the
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.Xr ahc 4
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and
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.Xr isp 4
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drivers fully support target mode.
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.Pp
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The
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.Xr ahc 4
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driver does not support tagged queuing in target mode.
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