xpt(4) [linux man page]
XPT(4) BSD Kernel Interfaces Manual XPT(4) 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> BSD October 10, 1998 BSD
Check Out this Related Man Page
PASS(4) BSD Kernel Interfaces Manual PASS(4) NAME
pass -- CAM application passthrough driver SYNOPSIS
device pass DESCRIPTION
The pass driver provides a way for userland applications to issue CAM CCBs to the kernel. Since the pass 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. The pass driver attaches to every SCSI device found in the system. Since it attaches to every device, it provides a generic means of access- ing SCSI devices, and allows the user to access devices which have no "standard" peripheral driver associated with them. KERNEL CONFIGURATION
It is only necessary to configure one pass device in the kernel; pass devices are automatically allocated as SCSI devices are found. IOCTLS
CAMIOCOMMAND This ioctl takes most kinds of CAM CCBs and passes them through to the CAM transport layer for action. Note that some CCB types are not allowed through the passthrough device, and must be sent through the xpt(4) device instead. Some examples of xpt-only CCBs are XPT_SCAN_BUS, XPT_DEV_MATCH, XPT_RESET_BUS, XPT_SCAN_LUN, XPT_ENG_INQ, and XPT_ENG_EXEC. These CCB types have various attributes that make it illogical or impossible to service them through the passthrough interface. CAMGETPASSTHRU This ioctl takes an XPT_GDEVLIST CCB, and returns the passthrough device corresponding to the device in question. Although this ioctl is available through the pass driver, it is of limited use, since the caller must already know that the device in question is a passthrough device if they are issuing this ioctl. It is probably more useful to issue this ioctl through the xpt(4) device. FILES
/dev/passn Character device nodes for the pass driver. There should be one of these for each device accessed through the CAM subsystem. DIAGNOSTICS
None. SEE ALSO
cam(3), cam(4), cam_cdbparse(3), xpt(4), camcontrol(8) HISTORY
The CAM passthrough driver first appeared in FreeBSD 3.0. AUTHORS
Kenneth Merry <ken@FreeBSD.org> BUGS
It might be nice to have a way to asynchronously send CCBs through the passthrough driver. This would probably require some sort of read/write interface or an asynchronous ioctl interface. BSD October 10, 1998 BSD