.. SPDX-License-Identifier: GPL-2.0
-=======================================
-Notes on Linux SCSI Generic (sg) driver
-=======================================
+========================
+SCSI Generic (sg) driver
+========================
20020126
Introduction
============
The SCSI Generic driver (sg) is one of the four "high level" SCSI device
-drivers along with sd, st and sr (disk, tape and CDROM respectively). Sg
+drivers along with sd, st and sr (disk, tape and CD-ROM respectively). Sg
is more generalized (but lower level) than its siblings and tends to be
used on SCSI devices that don't fit into the already serviced categories.
Thus sg is used for scanners, CD writers and reading audio CDs digitally
Major versions of the sg driver
===============================
-There are three major versions of sg found in the linux kernel (lk):
+There are three major versions of sg found in the Linux kernel (lk):
- sg version 1 (original) from 1992 to early 1999 (lk 2.2.5) .
It is based in the sg_header interface structure.
- sg version 2 from lk 2.2.6 in the 2.2 series. It is based on
Sg driver documentation
=======================
-The most recent documentation of the sg driver is kept at the Linux
-Documentation Project's (LDP) site:
+The most recent documentation of the sg driver is kept at
-- http://www.tldp.org/HOWTO/SCSI-Generic-HOWTO
+- https://sg.danny.cz/sg/
This describes the sg version 3 driver found in the lk 2.4 series.
-The LDP renders documents in single and multiple page HTML, postscript
-and pdf. This document can also be found at:
+Documentation (large version) for the version 2 sg driver found in the
+lk 2.2 series can be found at
-- http://sg.danny.cz/sg/p/sg_v3_ho.html
-
-Documentation for the version 2 sg driver found in the lk 2.2 series can
-be found at http://sg.danny.cz/sg/. A larger version
-is at: http://sg.danny.cz/sg/p/scsi-generic_long.txt.
+- https://sg.danny.cz/sg/p/scsi-generic_long.txt.
The original documentation for the sg driver (prior to lk 2.2.6) can be
-found at http://www.torque.net/sg/p/original/SCSI-Programming-HOWTO.txt
-and in the LDP archives.
+found in the LDP archives at
-A changelog with brief notes can be found in the
-/usr/src/linux/include/scsi/sg.h file. Note that the glibc maintainers copy
-and edit this file (removing its changelog for example) before placing it
-in /usr/include/scsi/sg.h . Driver debugging information and other notes
-can be found at the top of the /usr/src/linux/drivers/scsi/sg.c file.
+- https://tldp.org/HOWTO/archived/SCSI-Programming-HOWTO/index.html
A more general description of the Linux SCSI subsystem of which sg is a
-part can be found at http://www.tldp.org/HOWTO/SCSI-2.4-HOWTO .
+part can be found at https://www.tldp.org/HOWTO/SCSI-2.4-HOWTO .
Example code and utilities
and earlier
========= ==========================================================
-Both packages will work in the lk 2.4 series however sg3_utils offers more
-capabilities. They can be found at: http://sg.danny.cz/sg/sg3_utils.html and
+Both packages will work in the lk 2.4 series. However, sg3_utils offers more
+capabilities. They can be found at: https://sg.danny.cz/sg/sg3_utils.html and
freecode.com
Another approach is to look at the applications that use the sg driver.
Mapping of Linux kernel versions to sg driver versions
======================================================
-Here is a list of linux kernels in the 2.4 series that had new version
+Here is a list of Linux kernels in the 2.4 series that had the new version
of the sg driver:
- lk 2.4.0 : sg version 3.1.17
- lk 2.4.17 : sg version 3.1.22
.. [#] There were 3 changes to sg version 3.1.20 by third parties in the
- next six linux kernel versions.
+ next six Linux kernel versions.
-For reference here is a list of linux kernels in the 2.2 series that had
-new version of the sg driver:
+For reference here is a list of Linux kernels in the 2.2 series that had
+the new version of the sg driver:
- lk 2.2.0 : original sg version [with no version number]
- lk 2.2.6 : sg version 2.1.31
- lk 2.2.17 : sg version 2.1.39
- lk 2.2.20 : sg version 2.1.40
-The lk 2.5 development series has recently commenced and it currently
-contains sg version 3.5.23 which is functionally equivalent to sg
-version 3.1.22 found in lk 2.4.17.
+The lk 2.5 development series currently contains sg version 3.5.23
+which is functionally equivalent to sg version 3.1.22 found in lk 2.4.17.
Douglas Gilbert