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 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 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*                   are the control devices.

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.

Debian                                          November 15, 2002                                        TARG(4)