Browse Prior Art Database

Small Computer System Interface Linear Mapping Mechanism

IP.com Disclosure Number: IPCOM000107826D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 80K

Publishing Venue

IBM

Related People

Sotomayor Jr, GG: AUTHOR

Abstract

This article describes a technique by which a device driver for a specific small computer system interface (SCSI) device may create a linear ordering for the SCSI device that it wishes to support and also allows an individual device driver to determine what devices are to be included in that ordering.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Small Computer System Interface Linear Mapping Mechanism

       This article describes a technique by which a device
driver for a specific small computer system interface (SCSI) device
may create a linear ordering for the SCSI device that it wishes to
support and also allows an individual device driver to determine what
devices are to be included in that ordering.

      For purposes of this disclosure it is assumed that the device
driver is part of a SCSI sub-system and the SCSI sub-system provides
generic services.  One of the generic services that the SCSI sub-
system should provide is a list of all of the devices that are
attached to all of the SCSI buses on the particular system.  The form
of that data is not important, but it must contain some basic
information about the devices.  What must be included is:
o    card number
o    physical unit number (PUN)
o    logic unit number (LUN)

      It may also include other information, but that is not
required.

      An SCSI device driver will provide a list of devices that it
will support.  Each device that is supported contains an entry in a
table.  Each entry in the table contains information that would be
returned from an SCSI Device Inquiry command.  Some of the fields in
this table would be:
o    Device Type
o    Device Modifier
o    Vendor Name
o    Product Name
o    Revision Level
o    Revision Date

      To keep the table from growing excessively, the table can
contain wild cards in the ASCII fields.  Since the table may also
contain other information, wild cards can be used to customize the
various other fields for a device.  For example, a generic direct
memory access device (DASD) table entry may be provided, but to
support another specific DASD, it may be necessary for the device
driver to know that it is dealing with a specific DASD.  Wild cards
provide that ability.

      All of the device...