HP-UX Reference (11i v1 05/09) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

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scsi_ctl(7) scsi_ctl(7)

}

else

{

/* unknown state */

}

WARNINGS

Incorrect use of scsi_ctl operations (even those attempting access to non-existent devices) can cause

data loss, system panics, and device damage.

The SIOC_EXCLUSIVE

ioctl should be used to gain exclusive access to a device prior to attempting

SIOC_IO commands. If exclusive access is not obtained,

SIOC_IO commands will be intermixed with

device-speciﬁc driver commands, which can lead to undesirable results.

Device-speciﬁc drivers can reject inappropriate or troublesome

SIOC_IO commands. However, since not

all such operations are known and detected, care should be exercised to avoid disrupting device-speciﬁc

drivers when using commands that modify internal device states.

It is very easy to cause system deadlock through incorrect use of the

SIOC_PRIORITY_MODE

ioctl. Nor-

mally it is necessary to lock the calling process into memory (see plock(2)) prior to enabling priority mode.

Most

SCSI commands have a logical unit number (LUN) ﬁeld. Parallel

SCSI implementations on the HP-UX

operating system select logical units via the SCSI IDENTIFY message. The LUN portion of the cdb should

normally be set to zero, even when the LUN being accessed is not zero.

Use of linked commands is not supported.

Most SCSI commands with a data phase expect the data length information to be included somewhere in the

command bytes. Both the data_length ﬁeld and any cdb data length values must be correctly speciﬁed

to get correct command results.

Very large (or inﬁnite) timeout values can cause a parallel SCSI bus (potentially the entire system) to hang.

Device and/or bus reset operations can be used to regain a device’s attention when a timeout expires.

Resetting a device can cause

I/O errors and/or loss of cached data. This can result in loss of data and/or sys-

tem panics.

Obtaining SCSI INQUIRY data by use of the SIOC_INQUIRY ioctl instead of by use of the

SIOC_IO ioctl is

generally preferable since

SCSI implementations on the

HP-UX operating system synchronize access of

inquiry data during driver open calls.

Since communication parameters can be affected by device-speciﬁc driver capabilities, device-speciﬁc driver

use might result in communication parameter changes.

The

SIOC_CAPACITY ioctl is not supported by

scsi_ctl because the meaning of capacity is device-

speciﬁc.

FILES

/usr/include/sys/scsi.h

/usr/include/sys/scsi_ctl.h