aboutsummaryrefslogtreecommitdiff
path: root/Documentation/DocBook/scsi.tmpl
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/DocBook/scsi.tmpl')
-rw-r--r--Documentation/DocBook/scsi.tmpl409
1 files changed, 409 insertions, 0 deletions
diff --git a/Documentation/DocBook/scsi.tmpl b/Documentation/DocBook/scsi.tmpl
new file mode 100644
index 00000000..324b5349
--- /dev/null
+++ b/Documentation/DocBook/scsi.tmpl
@@ -0,0 +1,409 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
+
+<book id="scsimid">
+ <bookinfo>
+ <title>SCSI Interfaces Guide</title>
+
+ <authorgroup>
+ <author>
+ <firstname>James</firstname>
+ <surname>Bottomley</surname>
+ <affiliation>
+ <address>
+ <email>James.Bottomley@hansenpartnership.com</email>
+ </address>
+ </affiliation>
+ </author>
+
+ <author>
+ <firstname>Rob</firstname>
+ <surname>Landley</surname>
+ <affiliation>
+ <address>
+ <email>rob@landley.net</email>
+ </address>
+ </affiliation>
+ </author>
+
+ </authorgroup>
+
+ <copyright>
+ <year>2007</year>
+ <holder>Linux Foundation</holder>
+ </copyright>
+
+ <legalnotice>
+ <para>
+ This documentation is free software; you can redistribute
+ it and/or modify it under the terms of the GNU General Public
+ License version 2.
+ </para>
+
+ <para>
+ This program is distributed in the hope that it will be
+ useful, but WITHOUT ANY WARRANTY; without even the implied
+ warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ For more details see the file COPYING in the source
+ distribution of Linux.
+ </para>
+ </legalnotice>
+ </bookinfo>
+
+ <toc></toc>
+
+ <chapter id="intro">
+ <title>Introduction</title>
+ <sect1 id="protocol_vs_bus">
+ <title>Protocol vs bus</title>
+ <para>
+ Once upon a time, the Small Computer Systems Interface defined both
+ a parallel I/O bus and a data protocol to connect a wide variety of
+ peripherals (disk drives, tape drives, modems, printers, scanners,
+ optical drives, test equipment, and medical devices) to a host
+ computer.
+ </para>
+ <para>
+ Although the old parallel (fast/wide/ultra) SCSI bus has largely
+ fallen out of use, the SCSI command set is more widely used than ever
+ to communicate with devices over a number of different busses.
+ </para>
+ <para>
+ The <ulink url='http://www.t10.org/scsi-3.htm'>SCSI protocol</ulink>
+ is a big-endian peer-to-peer packet based protocol. SCSI commands
+ are 6, 10, 12, or 16 bytes long, often followed by an associated data
+ payload.
+ </para>
+ <para>
+ SCSI commands can be transported over just about any kind of bus, and
+ are the default protocol for storage devices attached to USB, SATA,
+ SAS, Fibre Channel, FireWire, and ATAPI devices. SCSI packets are
+ also commonly exchanged over Infiniband,
+ <ulink url='http://i2o.shadowconnect.com/faq.php'>I20</ulink>, TCP/IP
+ (<ulink url='http://en.wikipedia.org/wiki/ISCSI'>iSCSI</ulink>), even
+ <ulink url='http://cyberelk.net/tim/parport/parscsi.html'>Parallel
+ ports</ulink>.
+ </para>
+ </sect1>
+ <sect1 id="subsystem_design">
+ <title>Design of the Linux SCSI subsystem</title>
+ <para>
+ The SCSI subsystem uses a three layer design, with upper, mid, and low
+ layers. Every operation involving the SCSI subsystem (such as reading
+ a sector from a disk) uses one driver at each of the 3 levels: one
+ upper layer driver, one lower layer driver, and the SCSI midlayer.
+ </para>
+ <para>
+ The SCSI upper layer provides the interface between userspace and the
+ kernel, in the form of block and char device nodes for I/O and
+ ioctl(). The SCSI lower layer contains drivers for specific hardware
+ devices.
+ </para>
+ <para>
+ In between is the SCSI mid-layer, analogous to a network routing
+ layer such as the IPv4 stack. The SCSI mid-layer routes a packet
+ based data protocol between the upper layer's /dev nodes and the
+ corresponding devices in the lower layer. It manages command queues,
+ provides error handling and power management functions, and responds
+ to ioctl() requests.
+ </para>
+ </sect1>
+ </chapter>
+
+ <chapter id="upper_layer">
+ <title>SCSI upper layer</title>
+ <para>
+ The upper layer supports the user-kernel interface by providing
+ device nodes.
+ </para>
+ <sect1 id="sd">
+ <title>sd (SCSI Disk)</title>
+ <para>sd (sd_mod.o)</para>
+<!-- !Idrivers/scsi/sd.c -->
+ </sect1>
+ <sect1 id="sr">
+ <title>sr (SCSI CD-ROM)</title>
+ <para>sr (sr_mod.o)</para>
+ </sect1>
+ <sect1 id="st">
+ <title>st (SCSI Tape)</title>
+ <para>st (st.o)</para>
+ </sect1>
+ <sect1 id="sg">
+ <title>sg (SCSI Generic)</title>
+ <para>sg (sg.o)</para>
+ </sect1>
+ <sect1 id="ch">
+ <title>ch (SCSI Media Changer)</title>
+ <para>ch (ch.c)</para>
+ </sect1>
+ </chapter>
+
+ <chapter id="mid_layer">
+ <title>SCSI mid layer</title>
+
+ <sect1 id="midlayer_implementation">
+ <title>SCSI midlayer implementation</title>
+ <sect2 id="scsi_device.h">
+ <title>include/scsi/scsi_device.h</title>
+ <para>
+ </para>
+!Iinclude/scsi/scsi_device.h
+ </sect2>
+
+ <sect2 id="scsi.c">
+ <title>drivers/scsi/scsi.c</title>
+ <para>Main file for the SCSI midlayer.</para>
+!Edrivers/scsi/scsi.c
+ </sect2>
+ <sect2 id="scsicam.c">
+ <title>drivers/scsi/scsicam.c</title>
+ <para>
+ <ulink url='http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf'>SCSI
+ Common Access Method</ulink> support functions, for use with
+ HDIO_GETGEO, etc.
+ </para>
+!Edrivers/scsi/scsicam.c
+ </sect2>
+ <sect2 id="scsi_error.c">
+ <title>drivers/scsi/scsi_error.c</title>
+ <para>Common SCSI error/timeout handling routines.</para>
+!Edrivers/scsi/scsi_error.c
+ </sect2>
+ <sect2 id="scsi_devinfo.c">
+ <title>drivers/scsi/scsi_devinfo.c</title>
+ <para>
+ Manage scsi_dev_info_list, which tracks blacklisted and whitelisted
+ devices.
+ </para>
+!Idrivers/scsi/scsi_devinfo.c
+ </sect2>
+ <sect2 id="scsi_ioctl.c">
+ <title>drivers/scsi/scsi_ioctl.c</title>
+ <para>
+ Handle ioctl() calls for SCSI devices.
+ </para>
+!Edrivers/scsi/scsi_ioctl.c
+ </sect2>
+ <sect2 id="scsi_lib.c">
+ <title>drivers/scsi/scsi_lib.c</title>
+ <para>
+ SCSI queuing library.
+ </para>
+!Edrivers/scsi/scsi_lib.c
+ </sect2>
+ <sect2 id="scsi_lib_dma.c">
+ <title>drivers/scsi/scsi_lib_dma.c</title>
+ <para>
+ SCSI library functions depending on DMA
+ (map and unmap scatter-gather lists).
+ </para>
+!Edrivers/scsi/scsi_lib_dma.c
+ </sect2>
+ <sect2 id="scsi_module.c">
+ <title>drivers/scsi/scsi_module.c</title>
+ <para>
+ The file drivers/scsi/scsi_module.c contains legacy support for
+ old-style host templates. It should never be used by any new driver.
+ </para>
+ </sect2>
+ <sect2 id="scsi_proc.c">
+ <title>drivers/scsi/scsi_proc.c</title>
+ <para>
+ The functions in this file provide an interface between
+ the PROC file system and the SCSI device drivers
+ It is mainly used for debugging, statistics and to pass
+ information directly to the lowlevel driver.
+
+ I.E. plumbing to manage /proc/scsi/*
+ </para>
+!Idrivers/scsi/scsi_proc.c
+ </sect2>
+ <sect2 id="scsi_netlink.c">
+ <title>drivers/scsi/scsi_netlink.c</title>
+ <para>
+ Infrastructure to provide async events from transports to userspace
+ via netlink, using a single NETLINK_SCSITRANSPORT protocol for all
+ transports.
+
+ See <ulink url='http://marc.info/?l=linux-scsi&amp;m=115507374832500&amp;w=2'>the
+ original patch submission</ulink> for more details.
+ </para>
+!Idrivers/scsi/scsi_netlink.c
+ </sect2>
+ <sect2 id="scsi_scan.c">
+ <title>drivers/scsi/scsi_scan.c</title>
+ <para>
+ Scan a host to determine which (if any) devices are attached.
+
+ The general scanning/probing algorithm is as follows, exceptions are
+ made to it depending on device specific flags, compilation options,
+ and global variable (boot or module load time) settings.
+
+ A specific LUN is scanned via an INQUIRY command; if the LUN has a
+ device attached, a scsi_device is allocated and setup for it.
+
+ For every id of every channel on the given host, start by scanning
+ LUN 0. Skip hosts that don't respond at all to a scan of LUN 0.
+ Otherwise, if LUN 0 has a device attached, allocate and setup a
+ scsi_device for it. If target is SCSI-3 or up, issue a REPORT LUN,
+ and scan all of the LUNs returned by the REPORT LUN; else,
+ sequentially scan LUNs up until some maximum is reached, or a LUN is
+ seen that cannot have a device attached to it.
+ </para>
+!Idrivers/scsi/scsi_scan.c
+ </sect2>
+ <sect2 id="scsi_sysctl.c">
+ <title>drivers/scsi/scsi_sysctl.c</title>
+ <para>
+ Set up the sysctl entry: "/dev/scsi/logging_level"
+ (DEV_SCSI_LOGGING_LEVEL) which sets/returns scsi_logging_level.
+ </para>
+ </sect2>
+ <sect2 id="scsi_sysfs.c">
+ <title>drivers/scsi/scsi_sysfs.c</title>
+ <para>
+ SCSI sysfs interface routines.
+ </para>
+!Edrivers/scsi/scsi_sysfs.c
+ </sect2>
+ <sect2 id="hosts.c">
+ <title>drivers/scsi/hosts.c</title>
+ <para>
+ mid to lowlevel SCSI driver interface
+ </para>
+!Edrivers/scsi/hosts.c
+ </sect2>
+ <sect2 id="constants.c">
+ <title>drivers/scsi/constants.c</title>
+ <para>
+ mid to lowlevel SCSI driver interface
+ </para>
+!Edrivers/scsi/constants.c
+ </sect2>
+ </sect1>
+
+ <sect1 id="Transport_classes">
+ <title>Transport classes</title>
+ <para>
+ Transport classes are service libraries for drivers in the SCSI
+ lower layer, which expose transport attributes in sysfs.
+ </para>
+ <sect2 id="Fibre_Channel_transport">
+ <title>Fibre Channel transport</title>
+ <para>
+ The file drivers/scsi/scsi_transport_fc.c defines transport attributes
+ for Fibre Channel.
+ </para>
+!Edrivers/scsi/scsi_transport_fc.c
+ </sect2>
+ <sect2 id="iSCSI_transport">
+ <title>iSCSI transport class</title>
+ <para>
+ The file drivers/scsi/scsi_transport_iscsi.c defines transport
+ attributes for the iSCSI class, which sends SCSI packets over TCP/IP
+ connections.
+ </para>
+!Edrivers/scsi/scsi_transport_iscsi.c
+ </sect2>
+ <sect2 id="SAS_transport">
+ <title>Serial Attached SCSI (SAS) transport class</title>
+ <para>
+ The file drivers/scsi/scsi_transport_sas.c defines transport
+ attributes for Serial Attached SCSI, a variant of SATA aimed at
+ large high-end systems.
+ </para>
+ <para>
+ The SAS transport class contains common code to deal with SAS HBAs,
+ an aproximated representation of SAS topologies in the driver model,
+ and various sysfs attributes to expose these topologies and management
+ interfaces to userspace.
+ </para>
+ <para>
+ In addition to the basic SCSI core objects this transport class
+ introduces two additional intermediate objects: The SAS PHY
+ as represented by struct sas_phy defines an "outgoing" PHY on
+ a SAS HBA or Expander, and the SAS remote PHY represented by
+ struct sas_rphy defines an "incoming" PHY on a SAS Expander or
+ end device. Note that this is purely a software concept, the
+ underlying hardware for a PHY and a remote PHY is the exactly
+ the same.
+ </para>
+ <para>
+ There is no concept of a SAS port in this code, users can see
+ what PHYs form a wide port based on the port_identifier attribute,
+ which is the same for all PHYs in a port.
+ </para>
+!Edrivers/scsi/scsi_transport_sas.c
+ </sect2>
+ <sect2 id="SATA_transport">
+ <title>SATA transport class</title>
+ <para>
+ The SATA transport is handled by libata, which has its own book of
+ documentation in this directory.
+ </para>
+ </sect2>
+ <sect2 id="SPI_transport">
+ <title>Parallel SCSI (SPI) transport class</title>
+ <para>
+ The file drivers/scsi/scsi_transport_spi.c defines transport
+ attributes for traditional (fast/wide/ultra) SCSI busses.
+ </para>
+!Edrivers/scsi/scsi_transport_spi.c
+ </sect2>
+ <sect2 id="SRP_transport">
+ <title>SCSI RDMA (SRP) transport class</title>
+ <para>
+ The file drivers/scsi/scsi_transport_srp.c defines transport
+ attributes for SCSI over Remote Direct Memory Access.
+ </para>
+!Edrivers/scsi/scsi_transport_srp.c
+ </sect2>
+ </sect1>
+
+ </chapter>
+
+ <chapter id="lower_layer">
+ <title>SCSI lower layer</title>
+ <sect1 id="hba_drivers">
+ <title>Host Bus Adapter transport types</title>
+ <para>
+ Many modern device controllers use the SCSI command set as a protocol to
+ communicate with their devices through many different types of physical
+ connections.
+ </para>
+ <para>
+ In SCSI language a bus capable of carrying SCSI commands is
+ called a "transport", and a controller connecting to such a bus is
+ called a "host bus adapter" (HBA).
+ </para>
+ <sect2 id="scsi_debug.c">
+ <title>Debug transport</title>
+ <para>
+ The file drivers/scsi/scsi_debug.c simulates a host adapter with a
+ variable number of disks (or disk like devices) attached, sharing a
+ common amount of RAM. Does a lot of checking to make sure that we are
+ not getting blocks mixed up, and panics the kernel if anything out of
+ the ordinary is seen.
+ </para>
+ <para>
+ To be more realistic, the simulated devices have the transport
+ attributes of SAS disks.
+ </para>
+ <para>
+ For documentation see
+ <ulink url='http://sg.danny.cz/sg/sdebug26.html'>http://sg.danny.cz/sg/sdebug26.html</ulink>
+ </para>
+<!-- !Edrivers/scsi/scsi_debug.c -->
+ </sect2>
+ <sect2 id="todo">
+ <title>todo</title>
+ <para>Parallel (fast/wide/ultra) SCSI, USB, SATA,
+ SAS, Fibre Channel, FireWire, ATAPI devices, Infiniband,
+ I20, iSCSI, Parallel ports, netlink...
+ </para>
+ </sect2>
+ </sect1>
+ </chapter>
+</book>