freebsd-dev/share/man/man4/targ.4
2003-02-24 22:53:26 +00:00

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.\" Copyright (c) 2002
.\" Nate Lawson. All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" 2. Neither the name of the author nor the names of any co-contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY Nate Lawson AND CONTRIBUTORS ``AS IS'' AND
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" $FreeBSD$
.\"
.Dd November 15, 2002
.Dt TARG 4
.Os
.Sh NAME
.Nm targ
.Nd SCSI target emulator driver
.Sh SYNOPSIS
.Cd device targ
.Sh DESCRIPTION
The
.Nm
driver provides an interface for usermode programs to emulate SCSI target
devices.
A sample program that emulates a disk drive (similar to
.Xr da 4 )
can be found in
.Pa /usr/share/examples/scsi_target .
.Pp
The
.Nm
driver supplies control devices,
.Pa /dev/targ0 ,
.Pa /dev/targ1 ,
etc.
If a device is already in use,
.Xr open 2
will fail and
.Va errno
will be set to
.Er EBUSY .
After opening the device, the file descriptor must be bound to a
specific bus/target/LUN and enabled to process CCBs using the
.Dv TARGIOCENABLE
ioctl.
The process then uses
.Xr write 2
to send CCBs to the SIM and
.Xr poll 2
or
.Xr kqueue 2
to see if responses are ready.
Pointers to completed CCBs are returned via
.Xr read 2 .
Any data transfers requested by the user CCBs are done via zero-copy IO.
.Sh IOCTLS
The following
.Xr ioctl 2
calls are defined in the header file
.Aq Pa cam/scsi/scsi_targetio.h .
.Bl -tag -width ".Dv TARGIOCDISABLE"
.It Dv TARGIOCENABLE
.Pq Vt "struct ioc_enable_lun"
Enable target mode on the LUN specified by the following structure:
.Bd -literal -offset indent
struct ioc_enable_lun {
path_id_t path_id;
target_id_t target_id;
lun_id_t lun_id;
int grp6_len;
int grp7_len;
};
.Ed
.Pp
The selected path (bus), target, and LUN must not already be in use or
.Er EADDRINUSE
is returned.
If
.Va grp6_len
or
.Va grp7_len
are non-zero, reception of vendor-specific commands
is enabled.
.It Dv TARGIOCDISABLE
Disable target mode and abort all pending CCBs.
The CCBs may optionally be read as they complete.
.Dv TARGIOCENABLE
can then be called to activate a different LUN.
Multiple disable calls have no effect.
The
.Xr close 2
system call automatically disables target mode if enabled.
.It Dv TARGIOCDEBUG
.Pq Vt int
Enables
.Dv CAM_PERIPH
debugging if the argument is non-zero, otherwise disables
it.
.El
.Sh FILES
.Bl -tag -width ".Pa /sys/cam/scsi/scsi_target.c" -compact
.It Aq Pa cam/scsi/scsi_targetio.h
describes the usermode interface.
.It Pa /sys/cam/scsi/scsi_target.c
is the driver source file.
.It Pa /dev/targ*
are the control devices.
.El
.Sh SEE ALSO
.Pa /usr/share/examples/scsi_target ,
.Xr ahc 4 ,
.Xr isp 4 ,
.Xr scsi 4
.Rs
.%T "FreeBSD Target Information"
.%O http://www.root.org/~nate/freebsd/
.Re
.Sh BUGS
Currently, only the
.Xr ahc 4
and
.Xr isp 4
drivers fully support target mode.
.Pp
The
.Xr ahc 4
driver does not support tagged queuing in target mode.
.Sh AUTHORS
.An -nosplit
The
.Nm
driver first appeared in
.Fx 3.0
and was written by
.An Justin T. Gibbs .
It was rewritten
for
.Fx 5.0
by
.An Nate Lawson Aq nate@root.org .