Linux Fast-STREAMS

Linux Fast-STREAMS Installation and Reference Manual

About This Manual

This is Edition 3, last updated 2007-06-24, of The Linux Fast-STREAMS Installation and Reference Manual, for Version 0.9.2 release 3 of the Linux Fast-STREAMS package.

Preface

Notice

This package is released and distributed under the GPL (see GNU General Public License). Please note, however, that there are different licensing terms for the manual pages and some of the documentation (derived from OpenGroup¹ publications and other sources). Consult the permission notices contained in the documentation for more information.

This manual is released under the FDL (see GNU Free Documentation License) with all sections invariant.

Abstract

This manual provides a Installation and Reference Manual for Linux Fast-STREAMS.

Objective

The objective of this manual is to provide a guide for the STREAMS programmer when developing STREAMS modules, drivers and application programs for Linux Fast-STREAMS.

This guide provides information to developers on the use of the STREAMS mechanism at user and kernel levels.

STREAMS was incorporated in UNIX System V Release 3 to augment the character input/output (I/O) mechanism and to support development of communication services.

STREAMS provides developers with integral functions, a set of utility routines, and facilities that expedite software design and implementation.

Intent

The intent of this manual is to act as an introductory guide to the STREAMS programmer. It is intended to be read alone and is not intended to replace or supplement the Linux Fast-STREAMS manual pages. For a reference for writing code, the manual pages (see STREAMS(9)) provide a better reference to the programmer. Although this describes the features of the Linux Fast-STREAMS package, OpenSS7 Corporation is under no obligation to provide any software, system or feature listed herein.

Audience

This manual is intended for a highly technical audience. The reader should already be familiar with Linux kernel programming, the Linux file system, character devices, driver input and output, interrupts, software interrupt handling, scheduling, process contexts, multiprocessor locks, etc.

The guide is intended for network and systems programmers, who use the STREAMS mechanism at user and kernel levels for Linux and UNIX system communication services.

Readers of the guide are expected to possess prior knowledge of the Linux and UNIX system, programming, networking, and data communication.

Revisions

Take care that you are working with a current version of this manual: you will not be notified of updates. To ensure that you are working with a current version, contact the Author, or check The OpenSS7 Project website for a current version.

A current version of this manual is normally distributed with the Linux Fast-STREAMS package.

Version Control

     
     STREAMS.texi,v
     Revision 0.9.2.37  2007/03/17 08:31:56  brian
     - corrected formatting problems
     
     Revision 0.9.2.36  2007/02/28 06:30:55  brian
     - updates and corrections, #ifdef instead of #if
     
     Revision 0.9.2.35  2007/01/02 16:32:03  brian
     - updates for release, disable streams-bcm by default
     
     Revision 0.9.2.34  2006/12/31 13:26:37  brian
     - documentation updates for release
     
     Revision 0.9.2.33  2006/09/18 01:06:57  brian
     - updated manuals and release texi docs
     
     Revision 0.9.2.32  2006/08/28 10:47:05  brian
     - correction
     
     Revision 0.9.2.31  2006/08/28 10:32:54  brian
     - updated references
     
     Revision 0.9.2.30  2006/08/27 12:26:58  brian
     - finalizing auto release files
     
     Revision 0.9.2.29  2006/08/26 18:31:44  brian
     - handle long urls
     
     Revision 0.9.2.28  2006/08/26 09:18:27  brian
     - better release file generation
     
     Revision 0.9.2.27  2006/08/23 11:00:41  brian
     - added preface, corrections and updates for release
     
     Revision 0.9.2.26  2006/08/22 12:36:49  brian
     - udpates to documentation, tweaks to Stream head
     
     Revision 0.9.2.25  2006/03/22 10:02:04  brian
     - added makefile target index
     
     Revision 0.9.2.24  2006/03/03 10:57:11  brian
     - 32-bit compatibility support, updates for release
     
     Revision 0.9.2.23  2005/09/15 13:03:08  brian
     - added new graphics and updates
     
     Revision 0.9.2.22  2005/07/08 13:16:11  brian
     - updates to documentation
     
     Revision 0.9.2.21  2005/06/24 13:38:59  brian
     - added troubleshooting section to manuals
     
     Revision 0.9.2.20  2005/05/14 08:34:34  brian
     - copyright header correction
     
     Revision 0.9.2.19  2005/04/15 00:58:31  brian
     - working up documentation
     
     Revision 0.9.2.18  2005/04/14 08:06:09  brian
     - added figures
     
     Revision 0.9.2.17  2005/04/12 09:28:59  brian
     - corrections
     
     Revision 0.9.2.16  2005/04/11 20:48:41  brian
     - documentation updates and corrections
     
     Revision 0.9.2.15  2005/03/15 12:06:58  brian
     - Updated texinfo documentation.
     
     Revision 0.9.2.14  2005/03/15 00:56:42  brian
     - Updated version numbering in texinfo files.
     
     Revision 0.9.2.13  2005/03/15 00:51:34  brian
     - Updated version numbering in texinfo files.
     
     Revision 0.9.2.12  2005/02/17 22:57:34  brian
     - Some cross-reference corrections.
     
     Revision 0.9.2.11  2005/02/17 11:34:53  brian
     - Corrected some more texi problems.
     
     Revision 0.9.2.10  2005/01/24 11:57:57  brian
     - Updated texinfo headers.
     
     Revision 0.9.2.9  2004/12/19 15:15:02  brian
     - Corrected include position.
     
     Revision 0.9.2.8  2004/12/17 04:02:46  brian
     - Improving spec files.
     
     Revision 0.9.2.7  2004/11/06 10:24:35  brian
     - Updated documentation.
     
     Revision 0.9.2.6  2004/08/22 07:28:53  brian
     - Converted to shared common files.
     
     Revision 0.9.2.5  2004/08/22 06:17:50  brian
     - Checkin on new working branch.
     
     Revision 0.9.2.4  2004/08/15 19:59:29  brian
     - Build system updates.
     
     Revision 0.9.2.3  2004/05/29 08:28:01  brian
     - Working up stable release.
     
     Revision 0.9.2.2  2004/03/15 07:59:39  brian
     - Working up manual pages.
     
     Revision 0.9.2.1  2004/03/13 05:46:34  brian
     - Working up more documentation.
     

ISO 9000 Compliance

Only the TeX, texinfo, or roff source for this manual is controlled. An opaque (printed, postscript or portable document format) version of this manual is an UNCONTROLLED VERSION.

Disclaimer

OpenSS7 Corporation disclaims all warranties with regard to this documentation including all implied warranties of merchantability, fitness for a particular purpose, non-infringement, or title; that the contents of the manual are suitable for any purpose, or that the implementation of such contents will not infringe on any third party patents, copyrights, trademarks or other rights. In no event shall OpenSS7 Corporation be liable for any direct, indirect, special or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with any use of this manual or the performance or implementation of the contents thereof.

OpenSS7 Corporation reserves the right to revise this software and documentation for any reason, including but not limited to, conformity with standards promulgated by various agencies, utilization of advances in the state of the technical arts, or the reflection of changes in the design of any techniques, or procedures embodied, described, or referred to herein. OpenSS7 Corporation is under no obligation to provide any feature listed herein.

U.S. Government Restricted Rights

If you are licensing this Software on behalf of the U.S. Government ("Government"), the following provisions apply to you. If the Software is supplied by the Department of Defense ("DoD"), it is classified as "Commercial Computer Software" under paragraph 252.227-7014 of the DoD Supplement to the Federal Acquisition Regulations ("DFARS") (or any successor regulations) and the Government is acquiring only the license rights granted herein (the license rights customarily provided to non-Government users). If the Software is supplied to any unit or agency of the Government other than DoD, it is classified as "Restricted Computer Software" and the Government's rights in the Software are defined in paragraph 52.227-19 of the Federal Acquisition Regulations ("FAR") (or any successor regulations) or, in the cases of NASA, in paragraph 18.52.227-86 of the NASA Supplement to the FAR (or any successor regulations).

Acknowledgements

As with most open source projects, this project would not have been possible without the valiant efforts and productive software of the Free Software Foundation and the Linux Kernel Community.

Sponsors

Funding for completion of the OpenSS7 Linux Fast-STREAMS package was provided in part by:

Additional funding for The OpenSS7 Project was provided by:

Contributors

The primary contributor to the OpenSS7 Linux Fast-STREAMS package is Brian F. G. Bidulock. The following is a list of significant contributors to The OpenSS7 Project:

Authors

The authors of the OpenSS7 Linux Fast-STREAMS package include:

See Author Index, for a complete listing and cross-index of authors to sections of this manual.

Maintainer

The maintainer of the OpenSS7 Linux Fast-STREAMS package is:

Please send bug reports to bugs@openss7.org using the send-pr script included in the package, only after reading the BUGS file in the release, or See Problem Reports.

Web Resources

The OpenSS7 Project provides a website dedicated to the software packages released by the OpenSS7 Project.

Bug Reports

Please send bug reports to bugs@openss7.org using the send-pr script included in the Linux Fast-STREAMS package, only after reading the BUGS file in the release, or See Problem Reports. You can access the OpenSS7 GNATS database directly via the web, however, the preferred method for sending new bug reports is via mail with the send-pr script.

Mailing Lists

The OpenSS7 Project provides a number of general discussion Mailing Lists for discussion concerning the OpenSS7 Linux Fast-STREAMS package as well as other packages released by The OpenSS7 Project.

These are mailman mailing lists and so have convenient web interfaces for subscribers to control their settings. See http://www.openss7.org/mailinglist.html.

The mailing lists are as follows:

openss7

The openss7 mailing list is for general enquiries, information exchange and announcements regarding the OpenSS7 Project. This is our original mailing list and takes the highest amount of traffic.

openss7-announce

The openss7-announce mailing list is for announcements related to the OpenSS7 Project. This list will accept announcements posted by subscribers. Subscribe to this list if you are interested in announcements from the OpenSS7 Project, subscribers and sponsors, related to the OpenSS7 Project or STREAMS, SS7, SIGTRAN or SCTP in general.

openss7-cvs

The openss7-cvs mailing list is for automatic CVS log reporting. You must get permission of the owner to subscribe to this list. Subscribers are not allowed to post to this list, this is merely for distributing notification of changes to the CVS repository.h

openss7-develop

The openss7-develop mailing list is for email exchange related to the development projects under the OpenSS7 Project. This includes development requests, proposals, requests for comment or proposal. Subscribe to this list if you are interested in ongoing development details regarding the OpenSS7 Project.

openss7-test

The openss7-test mailing list is for email exchange related to the testing of code under the OpenSS7 Project. This specifically relates to conformance testing, verification testing, interoperability testing and beta testing. Subscribe to this list if you are interested in participating in and receiving ongoing details of test activities under the OpenSS7 Project.

openss7-bugs

The openss7-bugs mailing list is specifically tailored to bug tracking. The mailing list takes a feed from the OpenSS7 GNATS bug tracking system and accepts posting of responses to bug reports, tracking and resolution. Subscribe to this list if you are interested in receiving detailed OpenSS7 release code bug tracking information. This list is not archived; for historical information on problem reports, see our GNATS databases.

openss7-updates

The openss7-updates mailing list provides updates on OpenSS7 Project code releases and ongoing activities. Subscribers are not allowed to post to this list; this list is for official OpenSS7 Project announcements only. Subscribe to this list if you are interested in receiving updates concerning official releases and activities of the OpenSS7 Project.

openss7-streams

The openss7-streams mailing list is for email exchange related to the STREAMS development projects under the OpenSS7 Project. This includes development requests, proposals, requests for comment or proposal. Subscribe to this list if you are interested in ongoing development details regarding the OpenSS7 Project STREAMS components.

linux-streams

The linux-streams mailing list is for mail exchange related to Linux Fast-STREAMS or Linux STREAMS. This includes patches, development requests, proposals, requests for comment or proposal. Subscribe to this list if you are interested in ongoing development details regarding the STREAMS for Linux components. This is the the new (September 2006) home of the linux-streams list formerly of <gsyc.escet.urjc.es>.

Spam

To avoid spam being sent to the members of the OpenSS7 mailing list(s), we have blocked mail from non-subscribers. Please subscribe to the mailing list before attempting to post to them. (Attempts to post when not subscribed get bounced.)

As an additional measure against spam, subscriber lists for all OpenSS7 mailing lists are not accessible to non-subscribers; for most lists subscriber lists are only accessible to the list administrator. This keeps your mailing address from being picked off our website by bulk mailers.

Acceptable Use Policy

It is acceptable to post professional and courteous messages regarding the OpenSS7 package or any general information or questions concerning STREAMS, SS7, SIGTRAN, SCTP or telecommunications applications in general.

Large Attachments

The mailing list is blocked from messages of greater than 40k. If you have attachments (patches, test programs, etc.) and you mail them to the list, it will bounce to the list administrator. If you are interested in making your patches, test programs, test results or other large attachments available to the members of the mailing list, state in the message that you would like them posted and the list administrator will place them in the mail archives.

Quick Start Guide

Linux Fast-STREAMS

Package streams-0.9.2.3 was released under GPLv2 2007-06-24.

The OpenSS7 Linux Fast-STREAMS package is a High-Performance STREAMS framework for Linux that is compatible with SVR 4.2 MP STREAMS and a host of other commercial UNIX® STREAMS implementations, with complete debugging and production release capabilities. It is as a high-performance, production replacement for the buggy and now deprecated Linux STREAMS (LiS).

The Linux Fast-STREAMS package includes kernel modules, SVR 4.2 STREAMS drivers, modules, libraries, utilities, test programs, daemons, and development environment for the development and execution of STREAMS modules and drivers under Linux Fast-STREAMS. It is completely documented with over four hundred (435) manual pages, and three (3) major print set manuals.

The package configures, compiles, installs and builds rpms or debs for a wide range of Linux rpm(1)- or dpkg(1)-based distributions, and can be used on production kernels without patching, recompiling or tainting the kernel. Its small run-time footprint makes the release suitable for embedded targets.

This distribution is only currently applicable to Linux 2.4 and 2.6 kernels and was targeted at ix86, x86_64, ppc and ppc64 architectures, but should build and install for other architectures as well.

Release

This is the streams-0.9.2.3 package, released 2007-06-24. This `0.9.2.3' release, and the latest version, can be obtained from the download area of The OpenSS7 Project website using a command such as:

     $> wget http://www.openss7.org/tarballs/streams-0.9.2.3.tar.bz2

The release is available as an autoconf(1) tarball, src.rpm or dsc, or as a set of binary rpms or debs. See the download page for the autoconf(1) tarballs, src.rpms or dscs. See the streams package page for tarballs, source and binary packages.

Please see the NEWS file for release notes and history of user visible changes for the current version, and the ChangeLog file for a more detailed history of implementation changes. The TODO file lists features not yet implemented and other outstanding items.

Please see the INSTALL, INSTALL-streams and README-make, files (or see Installation) for installation instructions.

When working from cvs(1) or git(1), please see the README-cvs, file (or see Downloading from CVS). An abbreviated installation procedure that works for most applications appears below.

This release of the package is published strictly under Version 2 of the GNU Public License which can be found in the file COPYING. Package specific licensing terms (if any) can be found in the file LICENSES. Please respect these licensing arrangements. If you are interested in different licensing terms, please contact the copyright holder, or OpenSS7 Corporation <sales@openss7.com>.

See README-alpha (if it exists) for alpha release information.

Prerequisites

The quickest and easiest way to ensure that all prerequisites are met is to download and install this package from within the OpenSS7 Master Package, openss7-0.9.2.F, instead of separately.

Prerequisites for the Linux Fast-STREAMS package are as follows:

1. Linux distribution, somewhat Linux Standards Base compliant, with a 2.4 or 2.6 kernel and the appropriate tool chain for compiling out-of-tree kernel modules. Most recent Linux distributions are usable out of the box, but some development packages must be installed. For more information, see Compatibility.

   	− A fairly LSB compliant GNU/Linux distribution.2
   	− Linux 2.4 kernel (2.4.10 - 2.4.27), or
   	− Linux 2.6 kernel (2.6.3 - 2.6.21);
   	− glibc2 or better.
   	− GNU info (for info files).
   	− GNU groff (for man pages).3

When configuring and building multiple OpenSS7 Project release packages, place all of the source packages (unpacked tarballs) at the same directory level and all build directories at the same directory level (e.g. all source packages under /usr/src).

When installing packages that install as kernel modules, it is necessary to have the correct kernel development package installed. For the following distributions, use the following commands:

     Ubuntu:  $> apt-get install linux-headers
     Debian:  $> apt-get install kernel-headers
     Fedora:  $> yum install kernel-devel

You also need the same version of gcc(1) compiler with which the kernel was built. If it is not the default, add `CC=kgcc' on the line after `./configure', for example:

     $> ../streams-0.9.2.3/configure CC='gcc-3.4'

Installation

The following commands will download, configure, build, check, install, validate, uninstall and remove the package:

     $> wget http://www.openss7.org/tarballs/streams-0.9.2.3.tar.bz2
     $> tar -xjvf streams-0.9.2.3.tar.bz2
     $> mkdir build
     $> pushd build
     $> ../streams-0.9.2.3/configure --enable-autotest
     $> make
     $> make check
     $> sudo make install
     $> sudo make installcheck
     $> sudo make uninstall
     $> popd
     $> sudo rm -rf build
     $> rm -rf streams-0.9.2.3
     $> rm -f streams-0.9.2.3.tar.bz2

If you have problems, try building with the logging targets instead. If the make of a logging target fails, an automatic problem report will be generated that can be mailed to The OpenSS7 Project.⁴ Installation steps using the logging targets proceed as follows:

     $> wget http://www.openss7.org/tarballs/streams-0.9.2.3.tar.bz2
     $> tar -xjvf streams-0.9.2.3.tar.bz2
     $> mkdir build
     $> pushd build
     $> ../streams-0.9.2.3/configure --enable-autotest
     $> make compile.log
     $> make check.log
     $> sudo make install.log
     $> sudo make installcheck.log
     $> sudo make uninstall.log
     $> popd
     $> sudo rm -rf build
     $> rm -rf streams-0.9.2.3
     $> rm -f streams-0.9.2.3.tar.bz2

See README-make for additional specialized make targets.

For custom applications, see the INSTALL and INSTALL-streams files or the see Installation, as listed below. If you encounter troubles, see Troubleshooting, before issuing a bug report.

Brief Installation Instructions

The Linux Fast-STREAMS package is available from the downloads area of The OpenSS7 Project website using a command such as:

     $> wget http://www.openss7.org/tarballs/streams-0.9.2.3.tar.bz2

Unpack the tarball using a command such as:

     $> tar -xjvf streams-0.9.2.3.tar.bz2

The tarball will unpack into the relative subdirectory named after the package name: streams-0.9.2.3.

The package builds using the GNU autoconf utilities and the configure script. To build the package, we recommend using a separate build directory as follows:

     $> mkdir build
     $> cd build
     $> ../streams-0.9.2.3/configure

In general, the package configures and builds without adding any special options to the configure script. For general options to the configure script, see the GNU INSTALL file in the distribution:

     $> less ../streams-0.9.2.3/INSTALL

For specific options to the configure script, see the INSTALL-streams file in the distribution, or simply execute the configure script with the --help option like so:

     $> ../streams-0.9.2.3/configure --help

After configuring the package, the package can be compiled simply by issuing the `make' command:

     $> make

Some specialized makefile targets exists, see the README-make file in the distribution or simply invoke the `help' target like so:

     $> make help | less

After successfully building the package, the package can be checked by invoking the `check' make target like so:

     $> make check

After successfully checking the package, the package can be installed by invoking the `install' make target (as root) like so:

     $> sudo make install

The test suites that ship with the package can be invoked after the package has been installed by invoking the `installcheck' target. This target can either be invoked as root, or as a normal user, like so:

     $> make installcheck

(Note: you must add the --enable-autotest flag to configure, above for the test suites to be invoked with `make installcheck'.)

The package can be cleanly removed by invoking the `uninstall' target (as root):

     $> sudo make uninstall

Then the build directory and tarball can be simply removed:

     $> cd ..
     $> rm -rf build
     $> rm -rf streams-0.9.2.3
     $> rm -f streams-0.9.2.3.tar.bz2

Detailed Installation Instructions

More detailed installation instructions can be found in the Installation, contained in the distribution in `text', `info', `html' and `pdf' formats:

     $> cd ../streams-0.9.2.3
     $> less doc/manual/streams.txt
     $> lynx doc/manual/streams.html
     $> info doc/manual/streams.info
     $> xpdf doc/manual/streams.pdf

The `text' version of the manual is always available in the MANUAL file in the release.

The current manual is also always available online from The OpenSS7 Project website at:

     $> lynx http://www.openss7.org/streams_manual.html

1 Introduction

This manual documents the design, implementation, installation, operation and future development schedule of the Linux Fast-STREAMS package.

1.1 Overview

This manual documents the design, implementation, installation, operation and future development of the Linux Fast-STREAMS package.

1.2 Organization of this Manual

This manual is organized (loosely) into several sections as follows:

1.3 Conventions and Definitions

This manual uses texinfo typographic conventions.

2 Objective

2.1 Background

STREAMS derives from Dennis Ritchie's original paper,⁵ was incorporated into the UNIX® System V Release 3 operating system, replaced the terminal input-output subsystem, pipes and FIFOs in UNIX® System V Release 4, and was improved in the USL release of the UNIX® System V Release 4.2 operating system.

Today, STREAMS is a part of every major branded UNIX® variant, such as AIX®, HP-UX®, IRIX®, MacOT®, OSF/1®, Solaris®, SUPER-UX®, UnixWare®, UXP/V®, and including many UNIX-like operating systems and popular embedded RTOS, but with the notable exception of Berkeley System Distribution releases, variants and offshoots, and Linux.

2.2 What is STREAMS?

STREAMS is a flexible framework for communication between a user level process and a kernel resident driver. It encompasses a set of kernel system calls providing a user-kernel interface that is backward compatible with the traditional character device driver interface, as well as a set of STREAMS driver and module entry points forming a driver-kernel interface. STREAMS also provides a rich set of kernel utility functions for the development and implementation of kernel-resident drivers and modules. STREAMS prompted the specification of the DDI/DKI which is an architecture independent driver-kernel interface that provides a standardized set of kernel functions (beyond just STREAMS) for the development of device and software drivers.

STREAMS provides a reconfigurable full-duplex communications path between user level process and kernel resident driver, termed a Stream. Modules can be inserted in the path between the user and driver under user level control. Streams can be linked across multiplexers under user control to form complex (yet reconfigurable) topologies of user level processes and drivers.

Communication of control and data information along a Stream is accomplished by message passing. There is no direct function call interface between components of a Stream. A Stream exists within the STREAMS framework inside the kernel and extend from the user-kernel interface to the kernel driver interface. Each component of a Stream consists of a pair of queues used to pass messages in the upstream direction to the kernel-user interface; or downstream, the kernel-driver interface.

At the kernel-user end of the Stream is a component called the Stream head. As with all components of a Stream, the Stream head consists of a queue pair and a specialized set of procedures. The Stream head procedures are responsible for converting between the system call interface presented to users and the message passing mechanism within the Stream.

At the kernel-driver end of the Stream is the Stream end. The Stream end also contains a queue pair and a set of procedures. The Stream end (or simply driver) procedures are responsible for converting between the message passing mechanism within the Stream and the actions and events of a hardware (or pseudo-) device.

Intermediate components within the Stream are called Modules. Modules consist of a queue pair for passing messages upstream and downstream, as well as a set of procedures for processing messages. Modules can be pushed onto the module stack between the Stream head and Stream end using a set of standardized input-output control commands.

In support of topologies more complex than these simple linear segments, STREAMS also provides a specialized Stream end (driver) called a Multiplexing driver. A Multiplexing driver has the ability to open multiple Streams to its upper interface (multiplexer) as well as linking multiple Streams beneath its lower interface (multiplexer). Again, a standardized set of input-output controls provide the user with the ability to configure a Multiplexing driver.

2.3 Why STREAMS?

With the ability to open multiple Streams to a driver, push and pop modules to and from the module stack on a Stream, and to link any Stream under a multiplexing driver–all under user control using standardized input-output controls–allows STREAMS to configure complex topologies to form protocol stacks.

Almost all specialized standard telecommunications software developed since 1990 was developed to run on STREAMS. This is for several reasons:

• Since 1990, STREAMS and the associated DDI/DKI has been, and remains, the only way to incorporate OEM protocol stacks into mainstream UNIX® system kernels.
• The original UNIX System Laboratories (later X/Open then later the OpenGroup) support for ITU-T developed OSI protocols, makes STREAMS amenable to an open model for development for ITU-T protocols. (ITU-T, formerly CCITT, is the International Telecommunications Union – Telephone Sector responsible for international telephone standards, and original developers of the OSI model.)

As a result, there is a significant body of commercial software implementing telecommunications protocol stacks that was developed, tested, validated, conformance tested, field verified, to run on STREAMS: and is still running on STREAMS.

The cost of reimplementation, retesting, revalidation, redoing conformance testing, and field re-verification, would likely be prohibitive: after all, the point of Linux is reducing cost, is it not?

2.4 Why STREAMS for Linux?

The Linux kernel was not developed with STREAMS in mind. For TPI/IP networking, Linux originally followed in the footsteps of the BSD NET2 release. Currently, the implementation of TCP/IP in the Linux kernel has long departed from the classical BSD organization and exhibits characteristics unique to the GNU/Linux operating system. For character device and terminal input-output, Linux follows closely the SVR 3 pre-STREAMS approach to pipes, FIFOs and terminal subsystem. The terminal subsystem implementation, too, has become unique to GNU/Linux.

Therefore, from the perspective of TCP/IP networking and Terminal I/O, there would be little reason to provide STREAMS for Linux. That is, if it were not for the body of software supporting OSI and telecommunications protocols based solely on STREAMS, for which Linux has little or no support.

So, the answer to the question, "Why STREAMS for Linux?" is: so that a GNU/Linux platform can enjoy the same wealth of telecommunications and OSI protocol stacks otherwise only available to big-iron UNIX®. Without STREAMS, Linux is probably just another BSD, and probably not a very good one.

2.5 History of STREAMS for Linux

In the mid-90's, GCOM Inc. embarked on development on an open source implementation of STREAMS called Linux STREAMS (LiS), likely driven by its use for porting existing OSI protocol stacks to Linux. In 2000, The OpenSS7 Project abandoned using the Linux networking model for implementation of the Signalling System No. 7 protocol (primarily due to the lack of support for the full BSD networking model under Linux) and switched to using STREAMS as the basis for all future development. The GCOM LiS release (2.2 at the time) was used as the STREAMS package. Over the span of the next 5 years, (and not surprisingly given the body of software), almost all Signalling System No. 7 products released on Linux used LiS for STREAMS. In 2005, Dave Grothe (the G in GCOM) announced that he would no longer be maintaining or developing LiS subsequent to the 2.18.0 release, stranding many users of the package.

Later in 2005, after briefly maintaining two GPL'ed releases of LiS, (2.18.1 and 2.18.2), The OpenSS7 Project release (after two years of development) the streams-0.7a.4 package: a reimplementation of SVR 4.2 STREAMS with compatibility modules for all major UNIX® releases, called Linux Fast-STREAMS. Linux Fast-STREAMS was intended as a POSIX/SUSv3 XSR conforming, high performance, production grade, replacement for LiS, suitable for mainline Linux adoption, and a better foundation on which to base SIGTRAN, VoIP, ISDN and SS7 protocol stacks developed under the The OpenSS7 Project, as well as a better foundation for porting commercial UNIX® OEM implementations to Linux. It is the streams-0.9.2.3 package that contains the documentation you are reading now.

2.6 Why Fast?

After working with LiS releases for over 3 years, in late 2003, The OpenSS7 Project decided to begin implementation of a replacement for LiS, because of a number of shortcomings of the LiS releases:

1. unsuitable for mainline kernel adoption due to coding style and organization;
2. poorly adapted to distribution production kernels;
3. is unsuitable for packaging and repeatability;
4. portability objective unsuitable for mainline kernel adoption;
5. ports form the same baseline obfuscate the code;
6. performs poorly due to portability and coding style;
7. code bloat and over sized memory footprint;
8. redundant debug statements obscuring defects and obfuscating code;
9. overuse of semaphores;
10. contains serious races and not suitable for threaded applications;
11. does not conform to mainstream UNIX® implementations;
12. does not conform to POSIX or any release of the Single UNIX Specification;
13. limited set of standard drivers and modules;
14. limited set of diagnostic and administrative utilities;
15. limited test programs;
16. poorly documented.

The replacement, named Linux Fast-STREAMS, was to correct all of these difficulties, and, by the initial `streams-0.7a.4' release, was:

1. completely Lindented and follows kernel coding practises;
2. automatically adapts to production kernels with autoconf;
3. packages itself into LSB compliant RPMs and DEBs;
4. designed and implemented specifically for GNU/Linux;
5. no ports considered;
6. over twice the performance;
7. less than one-eighth of the memory footprint;
8. proper programming by assertion;
9. proper use of lightweight spin locks;
10. race free locking strategies and synchronization;
11. compatible with all mainstream UNIX® implementations;
12. conforms to POSIX/SUSv3 XSR;
13. complete set of standard drivers and modules;
14. complete set of diagnostic and administrative utilities;
15. integrated set of conformance test suites;
16. fully documented.

Many specific difficulties encountered with LiS not repeated by Linux Fast-STREAMS are contained in the COMPATIBILITY section of most of the manual pages.

3 Reference

3.1 Files

The following kernel modules are installed by Linux Fast-STREAMS in the /lib/modules/2.4.20-28.7/streams/directory, with either a `.o' or `.ko' extension. ⁶

specfs

This kernel module contains the STREAMS Special Shadow Filesystem. See specfs(5) for more information.

streams

This kernel module contains the STREAMS scheduler, utility functions, and STREAMS Device Driver Interface/Driver Kernel Interface (DDI/DKI). See STREAMS(9) for more information.

streams-fifo

This kernel module contains the fifo STREAMS driver. This is a standard STREAMS driver, but is also used by the conformance and validation test suite. See fifo(4) for more information.

streams-sad

This kernel module contains the sad STREAMS driver. This is the standard STREAMS Administrative Driver. See sad(4) for more information.

streams-nsdev

This kernel module contains the nsdev STREAMS driver. This is a Linux Fast-STREAMS specific driver. See nsdev(4) for more information.

streams-echo

This kernel module contains the echo STREAMS driver. This is a standard STREAMS driver, but is also used by the conformance and validation test suite. See echo(4) for more information.

streams-mux

This kernel module contains the mux STREAMS driver. This is a standard STREAMS driver< but is also used by the conformance and validation test suite. See mux(4) for more information.

streams-nuls

This kernel module contains the nuls STREAMS driver. This is a standard STREAMS module. See nuls(4) for more information.

streams-pipe

This kernel module contains the pipe STREAMS driver. This is a standard STREAMS driver. See pipe(4) for more information.

streams-log

This kernel module contains the log STREAMS driver. This is a standard STREAMS driver. See log(4) for more information.

streams-loop

This kernel module contains the loop STREAMS driver. This is a standard STREAMS driver, but is also used by the conformance and validation test suite. See loop(4) for more information.

streams-sfx

This kernel module contains the sfx STREAMS driver. This is a common character device driver for implementing STREAMS FIFOs. See sfx(4) for more information.

streams-spx

This kernel module contains the spx STREAMS driver. This is a common character device driver for implementing STREAMS pipes. See spx(4) for more information.

streams-bufmod

This kernel module contains the bufmod STREAMS module. The bufmod STREAMS module is a simple buffer module (a module that always defers to its service procedure and then passes any message along). This module is used for performance testing of the STREAMS package. See bufmod(4) for more information.

streams-nullmod

This kernel module contains the nullmod STREAMS module. The nullmod STREAMS module is a simple null module (a module that always passes messages to the next module in along the Stream). This module is used for performance testing of the STREAMS package and is also used by the conformance and validation test suite. See nullmod(4) for more information.

streams-pipemod

This kernel module contains the pipemod STREAMS module. This is a standard STREAMS module used with pipes. See pipemod(4) for more information.

streams-connld

This kernel module contains the connld STREAMS module. This is a standard STREAMS module. See connld(4) for more information.

streams-sc

This kernel module contains the sc STREAMS module. This is a common STREAMS Configuration module. See sc(4) for more information.

streams-testmod

This kernel module contains the testmod STREAMS module. This is a Linux Fast-STREAMS specific test module that is used for conformance and validation testing of STREAMS. See testmod(4) for more information.

Additional kernel modules are provided by add-on packages.

3.2 Drivers

The configuration of STREAMS drivers and modules is performed when compiling the Linux Fast-STREAMS subsystem. The STREAMS subsystem, core drivers and modules are part of every Linux Fast-STREAMS system.

The following lists the core drivers and modules, STREAMS kernel tunable parameters, and STREAMS configuration information:⁷

clone(4) (streams)

Clone device driver. This is a standard SVR 4.2 STREAMS driver. The clone(4) driver is a integral part of STREAMS and is used to create clone instances of a STREAMS driver.

See clone(4) for more information.

echo(4) (streams-echo)

Echo (loopback) device driver. This is a commonly implemented STREAMS driver. It is implemented by HP-UX® and OSF/1®. The echo(4) driver provides a simple FIFO-like device without full POSIX FIFO semantics. Its primary purpose is for the STREAMS Verification function, strvf(8), and the test-streams(8) validation test suite.

See echo(4) for more information.

fifo(4) (streams-fifo)

FIFO (Named Pipe) device driver. This is a standard SVR 4.2 STREAMS driver. The fifo(4) driver provides POSIX-compliant STREAMS-based FIFO device. Not all implementations of STREAMS provide STREAMS-based FIFOs: some implementations use the older SVR 3-style FIFOs that are not STREAMS-based. Linux Fast-STREAMS provides STREAMS-based FIFOs with the fifo(4) driver.

See fifo(4) for more information.

log(4) (streams-log)

STREAMS log driver. This is a standard SVR 4.2 STREAMS driver. The log(4) driver provides a STREAMS capable logger in addition to the BSD logger present in Linux. The log(4) driver provides additional support for STREAMS modules and drivers using the strlog(9) kernel level utility. Linux Fast-STREAMS also provides the strace(8), strerr(8) and strclean(8) administrative utility functions and startup scripts for controlling the log(4) driver.

See log(4) for more information.

loop(4) (streams-loop)

Loop device driver. This is a standard SVR 4.2 STREAMS driver. The loop driver is detailed in the UNIX System V Release 4 Programmer's Manual – STREAMS. The loop(4) driver provides capabilities used primarily for validation test programs (see test-streams(8)) as well as serving as an example driver.

See loop(4) for more information.

mux(4) (streams-mux)

Multiplexing driver. This is a standard SVR 4.2 STREAMS driver. The mux driver is detailed in the UNIX System V Release 4 Programmer's Manual – STREAMS. The mux(4) driver provides capabilities used primarily for validation test programs (see test-streams(8) as well as serving as an example multiplexing driver. This mux(4) driver also provides the minimux capabilities formerly present in LiS.

See mux(4) for more information.

nsdev(4) (streams-nsdev)

Named STREAMS device driver. This is a Linux Fast-STREAMS specific driver. The nsdev(4) driver is a clone(4)-like driver that permits the specification of major and minor device numbers using the device node name. It provides one of three mechanisms under Linux Fast-STREAMS that remove STREAMS driver dependency on statically allocated device numbers.

See nsdev(4) for more information.

nuls(4) (streams-nuls)

Null Stream driver. This is a standard SVR 4.2 STREAMS driver. The nuls(4) driver is usually called `null'. Linux has its own SVR3-style /dev/null driver, so it was renamed to `nuls'.

See nuls(4) for more information.

pipe(4) (streams-pipe)

STREAMS-based pipe driver. This is a standard SVR 4.2 STREAMS driver. However, pipe(4) is not normally implemented as a STREAMS driver, but is implemented as a system call. Linux Fast-STREAMS provides pipe(2s) system call emulation which invokes this driver internal to the kernel.

See pipe(4) for more information.

sad(4) (streams-sad)

STREAMS Administrative Driver. This is a standard SVR 4.2 STREAMS driver. The sad(4) driver is used by the autopush(8) utility to examine and specify the autopush lists for STREAMS drivers. Also, it is used to examine and verify the present of STREAMS modules or drivers in the system.

See sad(4) for more information.

sfx(4) (streams-sfx)

STREAMS FIFO device driver. This is commonly implemented STREAMS driver that is used to implement STREAMS FIFOs (Named Pipes) using a regular character device. The sfx(4) driver provides a character based device approach to creating FIFOs.

See sfx(4) for more information.

spx(4) (streams-spx)

STREAMS pipe device driver. This is commonly implemented STREAMS driver that is used to implement STREAMS pipes using a regular character device. The spx(4) driver provides a character based device approach to creating FIFOs and pipes. Only UnixWare® and AIX(4) document this device.

See spx(4) for more information.

Additional drivers are provided by add-on packages.

3.3 Modules

The configuration of STREAMS drivers and modules is performed when compiling the Linux Fast-STREAMS subsystem. The STREAMS subsystem, core drivers and modules are part of every Linux Fast-STREAMS system.

The following lists the core drivers and modules, STREAMS kernel tunable parameters, and STREAMS configuration information:⁸

pipemod(4) (streams-pipemod)

Pipe module. This is a standard SVR 4.2 STREAMS module. The pipemod(4) module can be pushed over a pipe end or FIFO before other modules are pushed (on either end) to reverse the sense of the M_FLUSH(9) message that traverse the pipe.

See pipemod(4) for more information.

connld(4) (streams-connld)

Connection Line Discipline module. This is a standard SVR 4.2 STREAMS module. The connld(4) module can be pushed over a pipe end that has been attached to a file system file using fattach(3) and will then create a new pipe instance on each open(2s) of the attached file and pass the new remove file pointer to the remove end using M_PASSFP(9) to be received with I_RECVFD(7). This allows servers to be created that use pipe(4)s for communication.

See connld(4) for more information.

sc(4) (streams-sc)

STREAMS Configuration module. This is a commonly implemented STREAMS module. It is implemented by HP-UX and AIX, and perhaps other Mentat-derived STREAMS implementations. The sc(4) modules provides the ability to access STREAMS driver information by name rather than major device number. It also provides access to the module_info(9) and module_stat(9) structure information for the named STREAMS module or driver, not accessible using the sad(4) driver. The sc(4) module is used by the scls(8) utility.

See sc(4) for more information.

bufmod(4) (streams-bufmod)

Buffer module. This is a standard SVR 4.2 STREAMS module described in the UNIX System V Release 4 Programmer's Manual – STREAMS. The bufmod(4) module also has Linux Fast-STREAMS specific extensions. The bufmod(4) module is used by the perftest(8) performance test program to test the effect of additional levels of service procedure pushed over a Stream. The module also serves as an example of a STREAMS module using service procedures.

See bufmod(4) for more information.

nullmod(4) (streams-nullmod)

Null module. This is a standard SVR 4.2 STREAMS module described in the UNIX System V Release 4 Programmer's Manual – STREAMS. The nullmod(4) module also has Linux Fast-STREAMS specific extensions. The nullmod(4) module is used by the perftest(8) performance test program to test the effect of additional levels of put procedure pushed over a Stream. The module also serves as an example of a STREAMS module not using service procedures.

See nullmod(4) for more information.

testmod(4) (streams-testmod)

Test module. This is a Linux Fast-STREAMS specific STREAMS module. The primary purpose of the testmod(4) modules is to provide the test-streams(8) validation test program with the capability to pass specific M_ERROR(9) and M_HANGUP(9) messages to the Stream head for POSIX validation testing. It also serves as an example of how a STREAMS module can properly process M_IOCTL(9) and related messages.

See testmod(4) for more information.

Additional modules are provided by add-on packages.

3.4 Libraries

During the installation process of Linux Fast-STREAMS a subroutine library is built and installed on your system. For 64-bit systems that support 32-bit compatibility, two versions of each library are built and installed: one 64-bit native library and one 32-bit compatibility library. 64-bit native libraries are installed to the /usr/lib64 subdirectory. 32-bit native and 32-bit compatibility libraries are installed to the /usr/lib subdirectory.

libstreams.so.0.0.1

libstreams.so.0

libstreams.so

Provides a shared object library for use by STREAMS applications programs.

libstreams.a

Provides a static library for use by STREAMS applications programs.

libstreams.la

Provides the libtool definitions for the library.

In addition to the libstreams library, Linux Fast-STREAMS also installs compatibility libraries for LiS. These compatibility libraries permit applications previously linked with LiS shared libraries to function with Linux Fast-STREAMS without recompiling or relinking.

libLiS.so.0.0.1

libLiS.so.0

libLiS.so

Provides a shared object library for use by legacy LiS applications programs.

libLiS.a

Provides a static library for use by legacy LiS applications programs.

libLiS.la

Provides the libtool definitions for the library.

libpLiS.so.0.0.1

libpLiS.so.0

libpLiS.so

Provides a shared object library for use by legacy LiS applications programs.

libpLiS.a

Provides a static library for use by legacy LiS applications programs.

libpLiS.la

Provides the libtool definitions for the library.

3.4.1 libstreams Library Routines

The following routines are present in the libstreams libraries. The routines in these libraries are standard STREAMS interface system calls documented in the System V Release 4.2 Programmer's Manual – STREAMS. Refer to the associated manual pages for detailed information on these routines.

fattach(2)

Name a STREAMS special file.

fdetach(2)

Unname a STREAMS special file.

getmsg(2)

Get next message off of a Stream.

getpmsg(2s)

Get next message off of a Stream.

isastream(2)

Test for a STREAMS special file.

pipe(2s)

Create a STREAMS pipe.

putmsg(2)

Put a message to a STREAMS character device.

putpmsg(2s)

Put a band message to a STREAMS character device.

pstrlog(3)

Print a STREAMS log buffer.

strlog(3)

Print a STREAMS log buffer.

vstrlog(3)

Print a STREAMS log buffer.

3.4.2 libLiS Library Routines

The following routines are present in the libLiS libraries. The routines are identical to the routines present in the libstreams library and are provided in the libLiS library for compatibility with existing applications linked against libLiS.

fattach(2)

Name a STREAMS special file.

fdetach(2)

Unname a STREAMS special file.

getmsg(2)

Get next message off of a Stream.

getpmsg(2s)

Get next message off of a Stream.

isastream(2)

Test for a STREAMS special file.

pipe(2s)

Create a STREAMS pipe.

putmsg(2)

Put a message to a STREAMS character device.

putpmsg(2s)

Put a band message to a STREAMS character device.

3.4.3 libpLiS Library Routines

The following routines are present in the libpLiS libraries. The libpLiS library is the same as the libLiS and libstreams libraries but omits the pipe(2s) subroutine. The purpose of the libpLiS library was to permit it to be used as a library preload without affecting the pipe(2s) function used by existing programs linked agai