Skip to content

Latest commit

 

History

History
653 lines (432 loc) · 37.3 KB

README.adoc

File metadata and controls

653 lines (432 loc) · 37.3 KB
Raw

Embench User Guide

Table of Contents

1. About Embench

Embench is a suite of free and open source C benchmarks, all of which are small real-world programs suitable for running on deeply embedded systems with at least 64kB of ROM and 16kB of RAM.

Embench is based on the following principles:

Embench must be free

  1. If behind a paywall, it is not going to be as widely used; and

  2. Academics publish frequently and can promote the use of benchmarks, so free and open accelerates their adoption and hence publicizes benchmarks to the rest of the community.

Embench must be easy to port and run

  1. If very difficult or expensive to port and run, then it will not be as widely used; and

  2. Linpack, Dhrystone, and CoreMark don’t have good reputations yet are widely reported presumably because they are free and easy to port and run.

Embench must be a suite of real programs

  1. Real programs are much likely to be representative than synthetic programs;

  2. A realistic workload is easier to represent as a suite of programs than as a single program;

  3. Compilers and hardware change rapidly, so benchmarks need to evolve over time to deprecate pieces that are newly irrelevant and add missing features that speak to current challenge;

  4. A single program is hard to evolve; and

  5. A suite of around 20 real programs means a more realistic workload that is much easier to evolve.

Embench must have a supporting organization that maintains its relevance over time

  1. Need an organization to evolve suite over time;

  2. Goal of refreshes every two years once we get to Embench 1.0; and

  3. Set up inside an existing organization, such as the Free and Open Source Silicon Foundation (FOSSi), rather than creating a new organization.

Embench must report a single summarizing performance score

  1. If no official single performance score, then it won’t be as widely reported

  2. Even worse, others may supply unofficial summaries that are either misleading or conflicting

  3. Might include orthogonal measures, like code size or power; each would have a summarizing score

Embench should use geometric mean and standard deviation to summarize

  1. Recommend first calculating the ratios of performance relative to a reference platform; and

  2. Report geometric mean (GM) of ratios + geometric standard deviation (GSD).

Embench must involve both academia and industry

  1. Academia helps maintain fair benchmarks for the whole field;

  2. Industry helps ensure that programs genuinely important in the real world; and

  3. We need both communities participating to succeed

1.1. The Bristol/Embecosm Embedded Benchmark Suite (BEEBS)

The benchmarks are largely derived from BEEBS (see http://beebs.eu), which in turn draws its material from various earlier projects, notably:

For the reasoning behind the choice of benchmarks in BEEBS, see "BEEBS: Open Benchmarks for Energy Measurements on Embedded Platforms." by J Pallister, S Hollis and J Bennett (http://arxiv.org/abs/1308.5174). For an example of BEEBS in use, see "Identifying Compiler Options to Minimise Energy Consumption for Embedded Platforms" by J Pallister, S Hollis and J Bennett (http://arxiv.org/abs/1303.6485).

1.2. Future work

This is a work in progress. The objective is that the task group will produce the first full release before the end of 2019.

1.3. Feedback and how to contribute

Comments on this document should be made through the Embench mailing list. Proposed changes may be submitted as git pull requests.

You are encouraged to contribute to this repository by submitting pull requests and by commenting on pull requests submitted by other people.

Note

Don’t forget to add your own name to the list of contributors in the document.

1.4. Contributors

This document has been created by the following people (in alphabetical order of surname).

Jeremy Bennett.

1.5. Document history

Revision Date Author Modification

0.5 Draft

6 June 2019

Jeremy Bennett

First draft of this document, drawing heavily on the BEEBS documentation.

2. Building and running Embench

Building follows standard GNU protocols.

2.1. Preparation

Unpack the software. Either extract from the supplied tar file:

tar xf embench-VERSION.tar.bz2

or clone the git repository:

git clone https://github.com/embench/embench.git

Embench is built out of tree, so create a separate directory in which to build along side.

mkdir bd
cd bd

2.2. Configuring the Build

Configure the software using the configure script in the main directory.

There several options available, most of which are standard to GNU configure scripts. Use configure --help to see all the options. The most useful is --host to specify the host triple for the board on which the test will be run. --prefix can be used to specify an installation location, although generally only the documentation is ever installed.

There are two configuration options which are specific to Embench.

--with-board=boardname

Specifies the board on which the tests will be run.

--with-chip=dir

Specifies the particular chip used with the tests, and is primarily used to set the particular command line options for the compiler and linker.

The board and chip names should match those of board or chip subdirectories within the config folder of the source tree, and the chip name should be the appropriate one for the chosen board. For example, to build for the RI5CY Verilator model with flags for a speed test, invoke the configure script as:

../beebs/configure --host=riscv32-unknown-elf \
                   --with-chip=speed-test \
                   --with-board=ri5cyverilator

The configure will look for a compiler named hostname-gcc or hostname-cc. To specify a different compiler, name it explicitly on the configuration line:

../beebs/configure --host=riscv32-unknown-elf \
                   --with-chip=speed-test \
                   --with-board=ri5cyverilator \
                   CC=riscv32-unknown-elf-clang

2.3. Building

Embench is built with:

make
Note

Embench is not generally installed (it works, but there is no point).

This documentation may be created and installed in alternative formats (PDF, HTML) with for example:

make pdf

If desired the documentation can be installed with:

make install-pdf

2.4. Running

The benchmark is run using:

make check

which will run both size and speed benchmarks. To run just the size benchmark use:

make check RUNTESTFLAGS="size.exp"

and to run just the speed benchmark use:

make check RUNTESTFLAGS="execute.exp"

It is also possible to run the benchmark on just a subset of the benchmarks, for example:

make check RUNTESTFLAGS="execute.exp=huffbench,slre"

will run just the speed test on the huffbench and slre benchmarks.

If an individual test takes too long to run, make check will timeout. If you wish to extend this, you can set the BEEBS_TIMEOUT environment variable.

BEEBS_TIMEOUT=300 make check RUNTESTFLAGS="execute.exp"

The size of programs is measured using the GNU size program. This reports three values, which are the size of the .text + .rodata sections, the size of the .data sections and the size of the .bss sections. Newer versions of size have an option, -G, which reports three different values, the size of the .text sections, the size of the .rodata + .data sections and the size of the .bss sections. If the size program found supports -G, this will be used by make check. You can control which size program to use, with the SIZE_PROG environment variable.

SIZE_PROG=riscv32-unknown-elf-size make check RUNTESTFLAGS="size.exp"

2.5. Known Issues

The following problems and issues are known about with Embench. Notify other issues by email to info@embench.org.

  • The configuration files assume bash.

3. Recording reliable results

For each benchmark run, you should record: * Details of the platform used, including its clock speed; * Details of the chip on the platform, including its precise architecture variant; * Details of the compiler tool chain used, typically the version of each component and library, or for development tool chains the repository commit ID of each component; and * The compiler and linker flags used, which should be the same for all benchmarks.

3.1. Computing a benchmark value for speed

Carry out the following steps:

  • For each benchmark record the time take to execute between start_benchmark and stop_benchmark, which should be a few seconds.

  • For each benchmark divide the time taken by the value used for CPU_MHZ in the configuration to give a normalized time value.

  • For each benchmark, compute its speed relative to the reference platform (see Reference platform) by dividing the normalized time value of the reference benchmark by the normalized time calculated in the previous step.

  • Calculate the geometric mean, geometric standard deviation and range of one geometric standard deviation of the relative speeds.

The benchmark value is the geometric mean of the relative speeds. A larger value means a faster platform. The range gives an indication of how much variability there is in this performance.

3.2. Computing a benchmark value for code size

Benchmarks should be compiled with dummy versions of all standard libraries. Carry out the following steps:

  • For each benchmark record the size of all .text sections.

  • For each benchmark, compute its size relative to the reference platform (see Reference platform) by dividing the size recorded in the previous step by the size of the corresponding reference benchmark.

  • Calculate the geometric mean, geometric standard deviation and range of one geometric standard deviation of the relative size.

The benchmark value is the geometric mean of the relative size. A larger value means code is larger. The range gives an indication of how much variability there is in this measurement.

Note

The computation of the relative value is inverted compared to the computation for speed. This means that for size, small is good.
Note

Older versions of the GNU size program report the size of .text + .rodata section. In measuring the size, ensure you use a modern version of size which supports the -G flag, which will yield the size of just .text sections.

3.3. Reference platform

The reference platform is a Verilator model of the PULP RI5CY core (see https://github.com/pulp-platform/riscv), commit 300762a. It uses a GCC tool chain built from top of tree, version 10.0.0 20190527, commit 4f90058758f.

Table 1. Table Reference platform data
Benchmark Speed Size

aha-mont64

4,000

1,052

crc32

4,013

230

cubic

4,140

2,466

edn

3,984

1,452

huffbench

4,109

1,628

matmult-int

4,020

420

minver

4,003

1,076

nbody

3,774

708

nettle-aes

3,988

2,874

nettle-sha256

4,000

5,558

nsichneu

4,001

15,036

picojpeg

3,747

8,022

qrduino

4,210

6,056

sglib-combined

4,028

2,316

slre

3,994

2,422

st

4,151

880

statemate

4,000

3,686

ud

4,001

702

wikisort

4,226

4,208
Note

Speed is measured in milliseconds, size is total size of all .text sections in bytes.

4. Documentation

4.1. AsciiDoc

This is a structured text format used by this document. Simple usage should be fairly self evident.

4.2. Installing documentation tools

To generate the documentation as HTML you need asciidoctor and to generate as PDF you need asciidoctor-pdf.

To spell check you need aspell installed.

4.3. Building the documentation

To build HTML:

make html

To build PDF:

make pdf

To check the spelling (excludes any listing or code phrases):

make spell

Any custom words for spell checking should be added to custom.wordlist.

5. Adding a New Board to Embench

5.1. Where to add files

If the board uses a completely new architecture, you will need to create a new subdirectory within the config directory.

cd config
mkdir ARCH

The architecture name comes from the first part of the host triplet (the --host configuration argument).

Within this ARCH directory create two separate directories for board and chip configurations

cd ARCH
mkdir boards
mkdir chips

If the architecture already has a board defined, these directories will already exist.

Then for your new board, create a directory in the chips directory for the chip it will use (if the directory does not already exist).

cd chips
mkdir CHIPNAME

The CHIPNAME corresponds to the argument given to --with-chip when configuring.

Similarly create a directory in the board directory for the new board. Since this is a new board, this directory will not already exist.

cd boards
mkdir BOARDNAME

The BOARDNAME corresponds to the argument given to --with-board when configuring.

5.2. Configuration files

Configuration data may be defined for the architecture, for the chip and for the board. These files are found respectively in

config/`ARCH/arch.cfg`
config/`ARCH/boards/BOARDNAME/board.cfg`
config/`ARCH/chips/CHIPNAME/chip.cfg`

Each of these is a bash shell script defining environment variables. These include

BOARD_CFLAGS

In board.cfg. Gives board specific CFLAGS

BOARD_LDFLAGS

In board.cfg. Gives board specific LDFLAGS

CHIP_CFLAGS

In chip.cfg. Gives chip specific CFLAGS

CHIP_LDFLAGS

In chip.cfg. Gives chip specific LDFLAGS

Architecture specific, board specific and chip specific values are combined, with board specific taking precedence over chip specific and chip specific taking precedence over architecture specific.

6. Header files

There are two standard header files which may be defined:

config/`ARCH/boards/BOARDNAME/boardsupport.h`
config/`ARCH/chips/CHIPNAME/chipsupport.h`

These are combined into the general header support.h which is included by all benchmarks, and defines values which may be used by the benchmarks. The values that may be defined are:

CPU_MHZ

Specifies the raw speed of the board (to the nearest megahertz). It is used to ensure that tests run for long enough on fast targets. Default value is 1.

Other values may be defined for use in board specific code.

7. Board specific code

Board specific code that is to be linked in to the benchmarks should be defined in config/`ARCH/boards/BOARDNAME/boardsupport.c`. This file should define the following functions.

initialize_board

Called to initialize the board.

start_trigger

Called at the start of the test run.

stop_trigger

Called at the end of the test run

It is usual for this file to include support.h to pick up any board and chip specific definitions that may prove useful.

Typically the tests are run using GDB and a remote GDB server to load the programs into a remote target. This can set breakpoint on start_trigger and stop_trigger to start and stop timing. In this case, these two function need no actual content, and the following is a sufficient implementation:

void
start_trigger ()
{
  __asm__ volatile ("" : : : "memory");
}

void
stop_trigger ()
{
  __asm__ volatile ("" : : : "memory");
}

By marking the inline assembly volatile and clobbering memory, we guarantee a function which will just contain a return statement.

Appendix A: The GNU Free Documentation License version 1.2, November 2002

Copyright © 2000,2001,2002 Free Software Foundation, Inc. 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA

Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

A.1. PREAMBLE

The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

A.2. APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document’s overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.

The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not "Transparent" is called "Opaque".

Examples of suitable formats for Transparent copies include plain ascii without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.

The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work’s title, preceding the beginning of the body of the text.

A section "Entitled XYZ" means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as "Acknowledgements", "Dedications", "Endorsements", or "History".) To "Preserve the Title" of such a section when you modify the Document means that it remains a section "Entitled XYZ" according to this definition.

The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

A.3. VERBATIM COPYING

You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and you may publicly display copies.

A.4. COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

A.5. MODIFICATIONS

You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

  1. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.

  2. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.

  3. State on the Title page the name of the publisher of the Modified Version, as the publisher.

  4. Preserve all the copyright notices of the Document.

  5. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.

  6. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.

  7. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice.

  8. Include an unaltered copy of this License.

  9. Preserve the section Entitled "History", Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.

  10. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.

  11. For any section Entitled "Acknowledgements" or "Dedications", Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.

  12. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.

  13. Delete any section Entitled "Endorsements". Such a section may not be included in the Modified Version.

  14. Do not retitle any existing section to be Entitled "Endorsements" or to conflict in title with any Invariant Section.

  15. Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version’s license notice. These titles must be distinct from any other section titles.

You may add a section Entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties---for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

A.6. COMBINING DOCUMENTS

You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections Entitled "History" in the various original documents, forming one section Entitled "History"; likewise combine any sections Entitled "Acknowledgements", and any sections Entitled "Dedications". You must delete all sections Entitled "Endorsements."

A.7. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

A.8. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an "aggregate" if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document’s Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

A.9. TRANSLATION

Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

If a section in the Document is Entitled "Acknowledgements", "Dedications", or "History", the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

A.10. TERMINATION

You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.

A.11. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/.

Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation.

A.12. ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:

Copyright (C)  YEAR  YOUR NAME.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.  A copy of the license is included in the section entitled "GNU Free Documentation License".

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the "with…​Texts." phrase with this:

with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.

If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.