targ (4)

Leading comments

 Copyright (c) 2002
	Nate Lawson.  All rights reserved.

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 modification, are permitted provided that the following conditions
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 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
 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
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(The comments found at the beginning of the groff file "man4/targ.4freebsd".)

NAME

targ - SCSI target emulator driver

SYNOPSIS

To compile this driver into the kernel, place the following line in your kernel configuration file:

device targ

DESCRIPTION

The driver provides an interface for usermode programs to emulate SCSI target devices. A sample program that emulates a disk drive (similar to da(4)) can be found in /usr/share/examples/scsi_target

The driver supplies the control device /dev/targ After opening the device, the file descriptor must be bound to a specific bus/target/LUN and enabled to process CCBs using the TARGIOCENABLE ioctl. The process then uses write(2) to send CCBs to the SIM and poll(2) or kqueue(2) to see if responses are ready. Pointers to completed CCBs are returned via read(2). Any data transfers requested by the user CCBs are done via zero-copy IO.

IOCTLS

The following ioctl(2) calls are defined in the header file In cam/scsi/scsi_targetio.h .

TARGIOCENABLE

(Vt struct ioc_enable_lun ) Enable target mode on the LUN specified by the following structure:

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;
};

The selected path (bus), target, and LUN must not already be in use or Er EADDRINUSE is returned. If grp6_len or grp7_len are non-zero, reception of vendor-specific commands is enabled.

TARGIOCDISABLE

Disable target mode and abort all pending CCBs. The CCBs may optionally be read as they complete. TARGIOCENABLE can then be called to activate a different LUN. Multiple disable calls have no effect. The close(2) system call automatically disables target mode if enabled.

TARGIOCDEBUG

(Vt int ) Enables CAM_PERIPH debugging if the argument is non-zero, otherwise disables it.

FILES

In cam/scsi/scsi_targetio.h

describes the usermode interface.

/sys/cam/scsi/scsi_target.c

is the driver source file.

/dev/targ

is the control device.

SEE ALSO

/usr/share/examples/scsi_target ahc(4), isp(4), scsi(4)

"FreeBSD Target Information"

AUTHORS

An -nosplit The 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 .

BUGS

Currently, only the ahc(4) and isp(4) drivers fully support target mode.

The ahc(4) driver does not support tagged queuing in target mode.