distributions  of GPL'd

software.  To comply with GPL's CCS requirements, the distributor

\textit{must} always know precisely what sources generated a given binary

distribution.

In an unfortunately large number of our enforcement cases, the violating

company's engineering team had difficulty reconstructing the CCS

for binaries distributed by the company.  Here are three simple rules to

follow to decrease the likelihood of this occurance:

\begin{itemize}

\item Ensure that your

developers are using revision control systems properly.

\item Have developers mark or ``tag'' the full source tree corresponding to

  builds distributed to customers

\item Check that your developers store all parts of the software

development in the revision control system, including {\sc readme}s, build

scripts, engineers' notes, and documentation.

\end{itemize}

Your developers will benefit anyway from these rules.  Developers will be

happier in their jobs if their tools already track the precise version of

source that corresponds to any deployed binary.

\section{Avoid the ``Build Guru''}

Too many software projects rely on only one or a very few team members who

know how to build and assemble the final released product.  Such knowledge

centralization not only creates engineering redundancy issues, but also

thwarts GPL compliance.  Specifically, CCS does not just require source code,

but scripts and other material that explain how to control compilation and

installation of the executable and object code.

Thus, avoid relying on a ``build guru'', a single developer who is the only one

who knows how to produce your final product. Make sure the build process

is well defined.  Train every developer on the build process for the final

binary distribution, including (in the case of embedded software)

generating a final firmware image suitable for distribution to the

customer.  Require developers to use revision control for build processes.

Make a rule that adding new components to the system without adequate

build instructions (or better yet, scripts) is unacceptable engineering

practice.

\chapter{Details of Compliant Distribution}

distributors of GPL'd software.  Note that this section refers heavily to

specific provisions and language in

\href{http://www.gnu.org/licenses/old-licenses/gpl-2.0.html#section3}{GPLv2}

and \href{http://www.fsf.org/licensing/licenses/gpl.html#section6}{GPLv3}.

It may be helpful to have a copy of each license open while reading this

section.

\section{Binary Distribution Permission}

\label{binary-distribution-permission}

% be careful below, you cannot refill the \if section, so don't refill

% this paragraph without care.

The various versions of the GPL are copyright licenses that grant

permission to make certain uses of software that are otherwise restricted

by copyright law.  This permission is conditioned upon compliance with the

GPL's requirements.\footnote{For a full discussion of this concept, please see

\ifpdf

\href{http://www.softwarefreedom.org/resources/2008/foss-primer.html\#x1-40002}{the

  chapter entitled ``Common Copyright Questions''} in SFLC's publication,

\href{http://www.softwarefreedom.org/resources/2008/foss-primer.pdf}{\textit{A

    Legal Issues Primer for Open Source and Free Software Projects}}.

\else

\ifx \generateHTML \isGeneratingHTML

\href{http://www.softwarefreedom.org/resources/2008/foss-primer.html\#x1-40002}{the

  chapter entitled ``Common Copyright Questions''} in SFLC's publication

\href{http://www.softwarefreedom.org/resources/2008/foss-primer.html}{\textit{A

    Legal Issues Primer for Open Source and Free Software Projects}}.

\else

the chapter entitled ``Common Copyright Questions'' in SFLC's publication,

\textit{A Legal Issues Primer for Open Source and Free Software

  Projects}.

\fi

\fi

}

This section walks through the requirements (of both GPLv2 and GPLv3) that

apply when you distribute GPL'd programs in binary (i.e., executable or

object code) form, which is typical for embedded applications.  Because a

binary application derives from a program's original sources, you need

permission from the copyright holder to distribute it.  \S~3 of GPLv2 and

\S~6 of GPLv3 contain the permissions and conditions related to binary

distributions of GPL'd programs.\footnote{These sections cannot be fully

  understood in isolation; read the entire license thoroughly before

  focusing on any particular provision.  However, once you have read and

  understood the entire license, look to these sections to guide

  compliance for binary distributions.}

GPL's binary distribution sections offer a choice of compliance methods,