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targ(4)

NAME

     targ -- SCSI target emulator driver

SYNOPSIS

     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 (simi-
     lar to da(4)) can be found in /usr/share/examples/scsi_target.

     The targ driver supplies control devices, /dev/targ0, /dev/targ1, etc.
     If a device is already in use, open(2) will fail and errno will be set to
     EBUSY.  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 com-
		     mands 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* 		  are the control devices.

SEE ALSO

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

     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>.

FreeBSD 5.4		       November 15, 2002		   FreeBSD 5.4

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