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sioc_io(7) sioc_io(7)

NAME

sioc_io - SCSI pass-through interface

DESCRIPTION

SCSI devices are controlled by a device-speciﬁc driver, when one exists. Device-speciﬁc drivers, such as

those for SCSI direct access (disk) and sequential access (tape) devices, coordinate device and driver

states to accomplish correct logical device behavior. The

sioc_io pass-through interface enables the

use of SCSI devices and commands not normally supported by these device-speciﬁc drivers.

Superuser privileges or device write permissions are required to use the

SIOC_IO ioctl. All reserved

ﬁelds in the

sioc_io data structure must be zero-ﬁlled.

The

SIOC_IO ioctl allows an arbitrary SCSI command to be sent to a device. All details of the SCSI com-

mand protocol are handled automatically.

The data structure for the

SIOC_IO ioctl is included from <

sys/scsi.h>:

/* SCSI device control ioctls */

#define SIOC_IO _IOWR(’S’, 22, struct sctl_io)

/* Structure for SIOC_IO ioctl */

struct sctl_io

{

unsigned flags;

unsigned char cdb_length;

unsigned char cdb[16];

void *data;

unsigned data_length;

unsigned max_msecs;

unsigned data_xfer;

unsigned cdb_status;

unsigned char sense[256];

unsigned sense_status;

unsigned char sense_xfer;

unsigned char reserved[64];

};

The following ﬂags can be used to specify the

flags ﬁeld value:

SCTL_READ Data-in phase expected if the data_length ﬁeld is non-zero. The absence of this

ﬂag implies that a data-out phase is expected if the data_length ﬁeld is non-

zero.

The

cdb ﬁeld speciﬁes the SCSI command bytes. The number of command bytes is speciﬁed by the

cdb_length ﬁeld. These command bytes are sent to the target device during the SCSI command phase.

The address of the data area for the data phase of the SCSI command is speciﬁed by the

data ﬁeld. The

data_length ﬁeld speciﬁes the maximum number of data bytes to be transferred. A zero-valued

data_length indicates that no data phase should occur. Most SCSI commands with a data phase

expect the data length information to be included somewhere in the command bytes. The caller is respon-

sible for correctly specifying both the data_length ﬁeld and any cdb data length values. The length

may not be larger than SCSI_MAXPHYS and some implementations further restrict this length.

The

max_msecs ﬁeld speciﬁes the maximum time, in milliseconds, that the device should need to com-

plete the command. If this period of time expires without command completion, the system might

attempt recovery procedures to regain the device’s attention. These recovery procedures might include

abort tag, abort, and device and bus reset operations. A zero value in the max_msec ﬁeld indicates that

the timeout period is inﬁnite and the system should wait indeﬁnitely for command completion.

When the

SIOC_IO ioctl call returns, all command processing has been completed. Most SIOC_IO ioctl

calls will return zero (success). The resulting detailed ioctl data should be used to evaluate ‘‘success’’ or

‘‘failure’’ from the caller’s perspective. The cdb_status ﬁeld indicates the results of the cdb command.

If the cdb_status ﬁeld indicates a S_CHECK_CONDITION status, the sense_status ﬁeld indicates

the results of the SCSI REQUEST SENSE command used to collect the associated sense data. These

status ﬁelds will contain one of the following values:

SCTL_INVALID_REQUEST The SCSI command request is invalid and thus not attempted.

Section 7−−146 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: September 2004