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targ (4)
>> targ (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
targ
- SCSI target emulator driver
SYNOPSIS
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 control devices,
/dev/targ0
/dev/targ1
etc.
If a device is already in use,
open(2)
will fail and
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
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.
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.
