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PASS(4) BSD Kernel Interfaces Manual PASS(4) NAME pass -- CAM application passthrough driver SYNOPSIS device pass device pass2 at scbus0 target 3 unit 0 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 accessing SCSI devices, and allows the user to access devices which have no "stan- dard" peripheral driver associated with them. KERNEL CONFIGURATION It is only necessary to configure one pass device in the kernel; pass de- vices 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 in- terface. CAMGETPASSTHRU This ioctl takes an XPT_GDEVLIST CCB, and returns the passthrough device corresponding to the device in ques- tion. Although this ioctl is available through the pass driver, it is of limited use, since the caller must al- ready know that the device in question is a passthrough device if they're issuing this ioctl. It is probably more useful to issue this ioctl through the xpt(4) de- vice. FILES /dev/passn Character device nodes for the pass driver. There should be one of these for each device accessed through the CAM subsys- tem. DIAGNOSTICS None. SEE ALSO cam(3), 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
NAME | SYNOPSIS | DESCRIPTION | KERNEL CONFIGURATION | IOCTLS | FILES | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHORS | BUGS
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