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⟩
