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Technical Reference: Kernel and Subsystems, Volume 2
SCIOREAD (Read) SCSI Adapter Device Driver ioctl Operation
Purpose
Issues a single block SCSI read
command to a selected SCSI device.
Description
The SCIOREAD operation allows
the caller to issue a SCSI device read command to a
selected adapter. System management routines use this command for configuring
SCSI devices.
The arg parameter of the SCIOREAD operation is the address of an sc_readblk structure. This structure is defined in the /usr/include/sys/scsi.h header file.
This command results in the SCSI adapter device driver
issuing a 6-byte format ANSI SCSI-1 read command. The
command is set up to read only a single block. The caller supplies:
- Target device SCSI and LUN ID
- Logical block number to be read
- Length (in bytes) of the block on the device
- Time-out value (in seconds) for the command
- Pointer to the application buffer where the returned
data is to be placed
- Flags parameter
The maximum block length for this command is 4096
bytes. The command will be rejected if the length is found to be larger than
this value.
The SC_ASYNC flag of the flag
parameter must not be set on the initial call to this operation. This flag
is set only if a bus fault occurs and only if this is the caller's last retry
attempt after this error occurs.
Note
The SCSI adapter device driver performs normal error-recovery
procedures during execution of this command.
Return Values
When completed successfully this operation returns
a value of 0. Otherwise, a value of -1 is returned and the errno global variable is set to one of the following values:
Value |
Description |
EFAULT |
Indicates that a bad copy between kernel and user space occurred. |
EINVAL |
Indicates that an SCIOSTART command was not
issued prior to this command. If the SCIOSTART command
was issued, then this indicates the block length field value is too large. |
EIO |
Indicates that an I/O error has occurred. If an EIO value is returned, the caller should retry the SCIOREAD operation since the first command may have cleared an error
condition with the device. In the case of an adapter error, the system error
log records the adapter error status information. |
ENOCONNECT |
Indicates that a bus fault has occurred. The caller should respond
by retrying with the SC_ASYNC flag set in the flag
byte of the passed parameters. If more than one retry is attempted, only
the last retry should be made with the SC_ASYNC flag
set. Generally, the SCSI adapter device driver cannot determine which device
caused the bus fault, so this error is not logged. |
ENODEV |
Indicates that no SCSI controller responded to the requested SCSI
ID. This return value implies that no logical unit numbers (LUNs) exist on
the specified SCSI ID. This condition is not necessarily an error and is
not logged. |
ENOMEM |
Indicates insufficient memory is available to complete the command. |
ETIMEDOUT |
Indicates the adapter did not respond with status before the internal
time-out value expired. The caller should retry this command at least once,
since the first command may have cleared an error condition with the device.
The system error log records this error. |
Files
/dev/scsi0, /dev/scsi1,..., /dev/scsin |
Provide an interface to allow SCSI device drivers to access SCSI
devices/adapters. |
/dev/vscsi0, /dev/vscsi1,...,
/dev/vscsin |
Provide an interface to allow SCSI-2 Fast/Wide Adapter/A and SCSI-2 Differential Fast/Wide Adapter/A
device drivers to access SCSI devices or adapters. |
Related Information
The rmt
SCSI device driver, scdisk
SCSI device driver, SCSI Adapter device driver, tmscsi SCSI device driver.
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