Initiating the I/O operation
The following list outlines the steps involved
when a peripheral driver initiates
a read request.
A similar process occurs for a write request.
Peripheral driver's read(D2osdi) routine-
Create and populate a
scsi_io_req(D4osdi)
(also called REQ_IO or request block)
structure to define the I/O operation.
This structure defines
various characteristics of the I/O operation,
and points to the
scsi_cdb(D4osdi)
Command Descriptor Block (CDB) structure
that tells the host adapter
what operation is required.
Then call the host adapter's
_entry(D2osdi)
routine that is defined in the peripheral driver's
scsi_dev_cfg(D4osdi)
structure and block with the
sleep(D3)
function.
Host adapter's _entry(D2osdi) routine-
extracts the
scsi_cdb(D4osdi)
(CDB or Command Descriptor Block)
from the REQ_IO structure
and initiates the appropriate I/O operation.
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