NAME¶
xpt
—
CAM transport layer interface
SYNOPSIS¶
None.
DESCRIPTION¶
The
xpt
driver provides a way for userland
applications to issue certain CAM CCBs to the kernel.
Since the
xpt
driver allows direct access to
the CAM subsystem, system administrators should exercise caution when granting
access to this driver. If used improperly, this driver can allow userland
applications to crash a machine or cause data loss.
KERNEL CONFIGURATION¶
There is no kernel configuration required for the
xpt
driver. It is enabled when SCSI support
is enabled in the kernel. There is one instance of the xpt driver per CAM
transport layer instance. Since there is currently only one CAM transport
layer, there will only be one instance of this driver.
IOCTLS¶
- CAMIOCOMMAND
- This ioctl takes certain kinds of CAM CCBs and passes them through to the
CAM transport layer for action. Only the following CCB types are
supported:
- XPT_SCAN_BUS
-
- XPT_RESET_BUS
-
- XPT_SCAN_LUN
-
- XPT_ENG_INQ
-
- XPT_ENG_EXEC
-
- XPT_DEBUG
-
- XPT_DEV_MATCH
-
- XPT_PATH_INQ
-
The above CCBs are the only ones supported since it makes more sense to send
them through a generic passthrough device rather than a passthrough device
tied to a particular underlying SCSI device.
- CAMGETPASSTHRU
- This ioctl takes an XPT_GDEVLIST CCB, and returns the passthrough device
corresponding to the device in question.
FILES¶
- /dev/xpt0
- Character device node for the
xpt
driver.
DIAGNOSTICS¶
None.
SEE ALSO¶
cam(3),
cam_cdbparse(3),
pass(4),
camcontrol(8)
HISTORY¶
The CAM transport layer driver first appeared in
FreeBSD
3.0.
AUTHORS¶
Kenneth Merry
⟨ken@FreeBSD.org⟩