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 targ 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 targ 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 <cam/scsi/scsi_targetio.h>.

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

FILES

     <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, http://www.root.org/~nate/freebsd/.

AUTHORS

     The targ driver first appeared in FreeBSD 3.0 and was written by Justin T. Gibbs.  It was rewritten for
     FreeBSD 5.0 by Nate Lawson <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.