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scsi - configuration files for SCSI target drivers The architecture of the illumos SCSI subsystem distinguishes two types of device drivers: SCSI target drivers, and SCSI host adapter drivers. Target drivers like sd(4D) and st(4D) manage the device on the other end of the SCSI bus. Host adapter drivers manage the SCSI bus on behalf of all the devices that share it.

Drivers for host adapters provide a common set of interfaces for target drivers. These interfaces comprise the Sun Common SCSI Architecture ( SCSA) which are documented as part of the illumos DDI/DKI. See scsi_ifgetcap(9F), scsi_init_pkt(9F), and scsi_transport(9F) for further details of these, and associated routines.

Depending on the interconnect (transport), SCSI target devices are either self-identifying or rely on driver.conf(5) entries to be recognized by the system. For self-identifying target devices the driver binding is chosen based on the IEEE-1275 like 'compatible' forms of the target devices. Currently the Fibre Channel interconnects, fcp(4D), ifp(4D), scsi_vhci(4D), sf(4D), and the SATA framework drivers (see sata(4D)) are self-identifying. You must specify other possible interconnects target devices by using the target driver driver.conf(5) configuration files.

Host adapter drivers of class scsi-self-identifying that dynamically create self-identifying target device children establish a compatible property on each child. The compatible property is an ordered array of strings, each string is a compatible form. High precedence forms are defined first. For a particular device, the highest precedence form that has an established driver alias selects the driver for the device. Driver associations to compatible forms, called aliases, are administered by way of add_drv(8), update_drv(8), and rem_drv(8) utilities.

The forms for self-identifying SCSI target devices are derived from the SCSI target device's INQUIRY data. A diverse set of forms is defined, allowing for flexibility in binding.

From the SCSI INQUIRY data, three types of information are extracted: scsi_dtype, flag bits, and SCSI_ASCII vendor product revision.

The scsi_dtype is the first component of most forms. It is represented as two hex digits. For nodes that represent embedded secondary functions, such as an embedded enclosure service or media changer, additional forms are generated that contain the dtype of the secondary function followed by the dtype of the device in which the secondary function is embedded.

For forms that use flag bits, all applicable flags are concatenated (in alphabetical order) into a single flags string. Removable media is represented by a flag. For forms that use the SCSI_ASCII INQUIRY vendor, product, and revision fields, a one-way conversion algorithm translates SCSI_ASCII to a IEEE 1275 compatible string.

It is possible that a device might change the INQUIRY data it returns over time as a result of a device initialization sequence or in response to out-of-band management. A device node's compatible property is based on the INQUIRY data when the device node was created.

The following forms, in high to low precedence order, are defined for SCSI target device nodes.

scsiclass,DDEEFFF.vVVVVVVVV.pPPPPPPPPPPPPPPPP.rRRRR (1 *1&2)
scsiclass,DDEE.vVVVVVVVV.pPPPPPPPPPPPPPPPP.rRRRR (2 *1)
scsiclass,DDFFF.vVVVVVVVV.pPPPPPPPPPPPPPPPP.rRRRR (3 *2)
scsiclass,DD.vVVVVVVVV.pPPPPPPPPPPPPPPPP.rRRRR (4)
scsiclass,DDEEFFF.vVVVVVVVV.pPPPPPPPPPPPPPPPP (5 *1&2)
scsiclass,DDEE.vVVVVVVVV.pPPPPPPPPPPPPPPPP (6 *1)
scsiclass,DDFFF.vVVVVVVVV.pPPPPPPPPPPPPPPPP (7 *2)
scsiclass,DD.vVVVVVVVV.pPPPPPPPPPPPPPPPP (8)
scsiclass,DDEEFFF (9 *1&2)
scsiclass,DDEE (10 *1)
scsiclass,DDFFF (11 *2)
scsiclass,DD (12)
scsiclass (13)
 *1 only produced on a secondary function node
 *2 only produced on a node with flags

where: v

VVVVVVVV p PPPPPPPPPPPPPPPP r RRRR DD EE FFF

illumos might create additional compatible forms not described. These forms are for illumos internal use only. Any additional use of these forms is discouraged. Future releases of illumos might not produce these forms.

Configuration files for SCSI target drivers should identify the host adapter driver implicitly using the class keyword to remove any dependency on the particular host adapter involved.

All host adapter drivers of class scsi recognize the following properties: target

lun

All SCSI target driver configuration file device definitions except stub device definitions for discovery of devid must provide target and lun properties. These properties are used to construct the address part of the device name under /devices. The stub device definitions for discovery of devid must be able to specify or imply the host adapter drivers that might have children that bind to the target driver. So all SCSI target driver configuration file stub device definitions must be defined by property class or parent.

The SCSI target driver configuration files shipped with illumos have entries for LUN 0 only. For devices that support other LUNs, such as some CD changers, the system administrator can edit the driver configuration file to add entries for other LUNs.

Example 1 An Example Configuration File for a SCSI Target Driver

The following is an example configuration file for a SCSI target driver called toaster.conf.

#
# Copyright (c) 1992, by Sun Microsystems, Inc.
#
#ident "@(#)toaster.conf 1.2 92/05/12 SMI"
name="toaster" class="scsi" target=4 lun=0;

Add the following lines to sd.conf for a six- CD changer on target 3, with LUNs 0 to 5.

name="sd" class="scsi" target=3 lun=1;
name="sd" class="scsi" target=3 lun=2;
name="sd" class="scsi" target=3 lun=3;
name="sd" class="scsi" target=3 lun=4;
name="sd" class="scsi" target=3 lun=5;

It is not necessary to add the line for LUN 0, as it already exists in the file shipped with illumos.

Example 2 A Stub Device Definition of sd.conf

The following line is a stub device definition which implies the host adapter drivers of class scsi-self-identifying might have children that bind to the sd(4D) driver:

name="sd" class="scsi-self-identifying";

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE

Interface Stability Committed

fcp (4D), ifp (4D), sata (4D), scsi_vhci (4D), sd (4D), sf (4D), st (4D), driver.conf (5), attributes (7), add_drv (8), rem_drv (8), update_drv (8), scsi_ifgetcap (9F), scsi_init_pkt (9F), scsi_transport (9F)

Writing Device Drivers

ANS X3T9.2/82-2 SMALL COMPUTER SYSTEM INTERFACE (SCSI-1)

ANS X3T9.2/375D Small Computer System Interface - 2 (SCSI-2)

ANS X3T10/994D SCSI-3 Architecture Model (SAM)

IEEE 1275 SCSI Target Device Binding

With driver.conf(5) configuration, you need to ensure that the target and lun values claimed by your target driver do not conflict with existing target drivers on the system. For example, if the target is a direct access device, the standard sd.conf file usually makes sd claim it before any other driver has a chance to probe it.