Writing Device Drivers

HBA Configuration Properties

When attaching an instance of an HBA device, scsi_hba_attach_setup(9F) creates a number of SCSI configuration parameter properties for that HBA instance. A particular property is created only if there is no existing property of the same name already attached to the HBA instance, permitting a default property value to be overridden in an HBA configuration file.

An HBA driver must use ddi_prop_get_int(9F) to retrieve each property. The HBA driver then modifies (or accepts the default value of) the properties to configure its specific operation.

scsi-reset-delay Property

The scsi-reset-delay property is an integer specifying the SCSI bus or device reset delay recovery time in milliseconds.

scsi-options Property

The scsi-options property is an integer specifying a number of options through individually defined bits. The bits in scsi_options are:

Per-target scsi-options

An HBA driver may support a per-target scsi-options feature in the following format:

	target<n>-scsi-options=<hex value>

In this example, < n> is the target ID. If the per-target scsi-options property is defined for a particular target, the HBA driver uses the value of the per-target scsi-options property for that target rather than the per-HBA driver instance scsi-options property. This can provide more precise control if, for example, synchronous data transfer needs to be disabled for just one particular target device. The per-target scsi-options property may be defined in the driver.conf(4) file.

Here is an example of a per-target scsi-options property definition to disable synchronous data transfer for target device 3: