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AIX Version 4.3 Kernel and Subsystems Technical Reference, 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:
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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