single, solitary act of copying, distributing or modifying software.

Almost always, a violator will have legitimately acquired a copy of a

GPL'd program, either making modifications or not, and then begun

distributing that work. For example, the violator may have put the

software in boxes and sold them at stores. Or perhaps the software

was put up for download on the Internet. Regardless of the delivery

mechanism, violators almost always are engaged in {\em ongoing\/}

violation of the GPL\@.

In fact, when we discover a GPL violation that occurred only once --- for

example, a user group who distributed copies of a GNU/Linux system without

source at one meeting --- we rarely pursue it with a high degree of

tenacity. In our minds, such a violation is an educational problem, and

unless the user group becomes a repeat offender (as it turns out, they

never do), we simply forward along a FAQ entry that best explains how user

groups can most easily comply with the GPL, and send them on their merry way.

It is only the cases of {\em ongoing\/} GPL violation that warrant our

active attention. We vehemently pursue those cases where dozens, hundreds

or thousands of customers are receiving software that is out of

compliance, and where the company continually offers for sale (or

distributes gratis as a demo) software distributions that include GPL'd

components out of compliance. Our goal is to maximize the impact of

enforcement and educate industries who are making such a mistake on a

large scale.

In addition, such ongoing violation shows that a particular company is

committed to a GPL'd product line. We are thrilled to learn that someone

is benefiting from Free Software, and we understand that sometimes they

become confused about the rules of the road. Rather than merely

giving us a postmortem to perform on a past mistake, an ongoing violation

gives us an active opportunity to educate a new contributor to the GPL'd

commons about proper procedures to contribute to the community.

Our central goal is not, in fact, to merely clear up a particular violation.

In fact, over time, we hope that our compliance lab will be out of

business. We seek to educate the businesses that engage in commerce

related to GPL'd software to obey the rules of the road and allow them to

operate freely under them. Just as a traffic officer would not revel in

reminding people which side of the road to drive on, so we do not revel in

violations. By contrast, we revel in the successes of educating an

ongoing violator about the GPL so that GPL compliance becomes a second-nature

matter, allowing that company to join the GPL ecosystem as a contributor.

\section{How are Violations Discovered?}

Our enforcement of the GPL is not a fund-raising effort; in fact, FSF's GPL

Compliance Lab runs at a loss (in other words, it is subsided by our

donors). Our violation reports come from volunteers, who have encountered,

in their business or personal life, a device or software product that

appears to contain GPL'd software. These reports are almost always sent

via email to $<$license-violation@fsf.org$>$.

Our first order of business, upon receiving such a report, is to seek

independent confirmation. When possible, we get a copy of the software

product. For example, if it is an offering that is downloadable from a

Web site, we download it and investigate ourselves. When it is not

possible for us to actually get a copy of the software, we ask the

reporter to go through the same process we would use in examining the

software.

By rough estimation, about 95\% of violations at this stage can be

confirmed by simple commands. Almost all violators have merely made an

error and have no nefarious intentions. They have made no attempt to

remove our copyright notices from the software. Thus, given the

third-party binary, {\tt tpb}, usually, a simple command (on a GNU/Linux

system) such as the following will find a Free Software copyright notice

and GPL reference:

\begin{quotation}

{\tt strings tpb | grep Copyright}

\end{quotation}

In other words, it is usually more than trivial to confirm that GPL'd

software is included.

Once we have confirmed that a violation has indeed occurred, we must then

determine whose copyright has been violated. Contrary to popular belief,

FSF does not have the power to enforce the GPL in all cases. Since the GPL

operates under copyright law, the powers of enforcement --- to seek

redress once \S 4 has been invoked --- lie with the copyright holder of

the software. FSF is one of the largest copyright holders in the world of

GPL'd software, but we are by no means the only one. Thus, we sometimes

discover that while GPL'd code is present in the software, there is no

software copyrighted by FSF present.

In cases where FSF does not hold copyright interest in the software, but

we have confirmed a violation, we contact the copyright holders of the

software, and encourage them to enforce the GPL\@. We offer our good offices

to help negotiate compliance on their behalf, and many times, we help as a

third party to settle such GPL violations. However, what we will describe

primarily in this course is FSF's first-hand experience enforcing its own

copyrights and the GPL\@.

\section{First Contact}

The Free Software community is built on a structure of voluntary

cooperation and mutual help. Our community has learned that cooperation

works best when you assume the best of others, and only change policy,

procedures and attitudes when some specific event or occurrence indicates

that a change is necessary. We treat the process of GPL enforcement in

the same way. Our goal is to encourage violators to join the cooperative

community of software sharing, so we want to open our hand in friendship.

Therefore, once we have confirmed a violation, our first assumption is

that the violation is an oversight or otherwise a mistake due to confusion

about the terms of the license. We reach out to the violator and ask them

to work with us in a collaborative way to bring the product into

compliance. We have received the gamut of possible reactions to such

requests, and in this course, we examine four specific examples of such

compliance work.

% FIXME: make this section properly TeX-formatted

\chapter{ThinkPenguin Wireless Router: Excellent CCS}

Too often, case studies examine failure and mistakes.  Indeed, most of the

chapters that follow herein will consider the myriad difficulties discovered

in community-oriented GPL enforcement for the last two decades.  However, to

begin, this is a case study in how copyleft compliance can indeed be done correctly.

This example is, in fact, more than ten years in the making.  Since almost

the inception of for-profit corporate adoption of Free Software, companies

have requested a clear example of a model citizen to emulate.  Sadly, while

community-oriented enforcers have vetted uncounted thousands of ``Complete,

Corresponding Source'' (CCS) candidates from hundreds of companies, this

particular CCS release described herein is the first ever declared a ``pristine

example''.

% FIXME (above): link to a further discussion of CCS in the compliance guide

% when a good spot exists, then (below) link to a ``CCS iteration''

% discussion in compliance-guide.tex when one exists.  (the ``iteration

% process'' is discussed in~\ref{} of this guide)

Of course, most CCS examined for the last decade has (eventually) complied

with the GPL, perhaps after many iterations of review by the enforcer.

However, in the experience of the two primary community-oriented enforcers

(Conservancy and the FSF), such CCS results routinely 

``barely comply with GPL's requirements''.  To use an academic analogy:

while a ``C'' is certainly a passing grade, any instructor prefers to

disseminate to the class an exemplar sample that earned an ``A''.

Fortunately, thanks in large part to the FSF's

``Respects Your Freedom'' (RYF) certification campaign\footnote{\href{http://www.fsf.org/resources/hw/endorsement/respects-your-freedom}{RYF is

    a campaign by FSF to certify products that truly meet the principles of

    software freedom}.  Products must meet

  \href{http://www.fsf.org/resources/hw/endorsement/criteria}{strict

    standards for RYF certification}, and among them is a pristine example of

  CCS\@.}, a few electronics products on the market meet

a higher standard of copyleft compliance.  As such, for the first

time in the history of copyleft, CCS experts have pristine examples to study

and present as exemplars worthy of emulation.

This case study therefore examines the entire life-cycle of a GPL compliance

investigation: from product purchase, to source request, to CCS review, and concluding

in a final compliance determination.

Specifically, this chapter discusses the purchase, CCS provision, and a

step-by-step build and installation analysis of a specific, physical,

embedded electronics product:

\href{https://www.thinkpenguin.com/gnu-linux/free-software-wireless-n-broadband-router-gnu-linux-tpe-nwifirouter}{the

  ``TPE-NWIFIROUTER'' wireless router by ThinkPenguin}.\footnote{The FSF of

  course performed a thorough CCS check as part of its certification process.

  The analysis discussed herein was independently performed by Software

  Freedom Conservancy without reviewing the FSF's findings.  Thus, this

  analysis is ``true to form'', and explains the typical procedures Conservancy

  uses when investigating a potential GPL violation.  In this case, obviously, no

  violation was uncovered.}

\section{Consumer Purchase and Unboxing}

The process for copyleft compliance investigation, when properly conducted,

determines whether users inclined to exercise their rights under a copyleft

license will be successful in their attempt.  Therefore, at every stage, the

investigator seeks to take actions that reasonably technically knowledgeable

users would during the ordinary course of their acquisition and use of

copyleft-covered products.  As such, the investigator typically purchases the device on the

open market to verify that distribution of the copylefted software therein

complies with binary distribution requirements (such as those

\tutorialpartsplit{discussed in \textit{Detailed Analysis of the GNU GPL and

    Related Licenses}}{discussed earlier in \S~\ref{GPLv2s3} and

  \S~\ref{GPLv3s6}}).

% FIXME: Above is my only use of \tutorialpartsplit in this chapter.  I just

% got lazy and that should be fixed by someone.

\label{thinkpenguin-included-ccs}

Therefore, the investigator first purchased the TPE-NWIFIROUTER through an

online order, and when the package arrived, examined the contents of the box.

The investigator immediately discovered that ThinkPenguin had taken advice

from \S~\ref{offer-for-source}, and exercised

\hyperref[GPLv2s3a]{GPLv2\S3(a)} and \hyperref[GPLv3s6]{GPLv3\S6}, rather than

using the \hyperref[offer-for-source]{problematic offer for source

  provisions}.  This choice not only accelerated the investigation (since there

was no CCS offer to ``test''), but also simplified the compliance requirements for

ThinkPenguin.

\section{Root Filesystem and Kernel Compilation}

The CD found in the box was labeled ``libreCMC v1.2.1 source code'', and

contained 407 megabytes of data.  The investigator copied this ISO to a

desktop GNU/Linux system and

examined its contents.  Upon doing so, the investigator immediately found a

file called ``README'' at the top-level directory:

\lstset{tabsize=2}

\begin{lstlisting}[language=bash]

$ dd if=/dev/cdrom of=libreCMC_v1.2.1_SRC.iso

$ mkdir libCMC

$ sudo mount -o loop ./libreCMC_v1.2.1_SRC.iso libCMC

mount: block device /path/to/libreCMC_v1.2.1_SRC.iso

       is write-protected, mounting read-only

$ ls -1 libCMC

bin

librecmc-u-boot.tar.bz2

librecmc-v1.2.1.tar.bz2

README

u-boot_reflash

$ cat libCMC/README

...

\end{lstlisting}

\label{thinkpenguin-toplevel-readme}

The investigator therefore knew immediately to begin the CCS check should

begin with a study of the contents of ``README''.  Indeed, that file contained the appropriate

details to start the build:

\begin{quotation}

In order to build firmware images for your router, the following needs to be

installed:

gcc, binutils, bzip2, flex, python, perl, make, find, grep, diff, unzip,

gawk, getopt, libz-dev and libc headers.

Please use ``make menuconfig'' to configure your appreciated configuration

for the toolchain and firmware. Please note that the default configuration is

what was used to build the firmware image for your router. It is advised that

you use this configuration.

Simply running ``make'' will build your firmware.  The build system will

download all sources, build the cross-compile toolchain, the kernel and all

chosen applications.

To build your own firmware you need to have access to a GNU/Linux system

(case-sensitive filesystem required).

\end{quotation}

In other words, the first ``script'' that investigator ``ran'' was the above.

This was not a software script, rather the processor for the script was the investigator's own

brain --- like a script of a play.  Less glibly stated: instructions written in

English are usually necessary for the build and installation operations

that demand actual intelligence.

In this case, the investigator ascertained the host system requirements

for construction of this embedded firmware.

GPL does not give specific guidance on the form or location of

``scripts used to control compilation and installation of the executable''

and/or ``Installation Information''.  Community-oriented GPL enforcers apply a

``reasonableness standard'' to evaluate such instructions.  If an investigator of

average skill in embedded firmware construction can surmise the proper

procedures to build and install a replacement firmware, the instructions are

likely sufficient to meet GPL's requirements.  Fortunately, in this case, the

instructions are more abundant and give extra detail.

Nevertheless, these instructions offer more options than the reader

typically sees in other CCS candidates.  More typically, top-level build

instructions name an exact host distribution to use, such as

``Debian 7 installed on an amd64 system with the following packages

installed''.  Of course, if the build will fail on any other system,

instructions \textit{should} include such details.  However, this CCS builds

on a wide range of distributions, and thus it was appropriate (and preferred)

that the build instructions do not  specify a specific distribution.

\label{thinkpenguin-specific-host-system}

In this specific case, the developers of the libreCMC project (a Free

Software project that forms the base system for the TPE-NWIFIROUTER) have

clearly made an effort to ensure the CCS builds on a variety of host systems.

The investigator was in fact dubious upon seeing these instructions, since

finicky embedded build processes usually require a very specific host system.

Fortunately, it seems such doubts were generally unfounded (although the

investigator did find

\hyperref[thinkpenguin-glibc-214-issue]{a minor annoyance that could be

  resolved with more detailed instructions}).

Anyway, since these instructions did not specify a specific host system, the

investigator simply used his own amd64 Debian GNU/Linux 6 desktop system.  Before

beginning, the investigator used the following command:

\lstset{tabsize=2}

\begin{lstlisting}[language=bash]

$ dpkg --list | egrep '^iii' | less

\end{lstlisting}

to verify that the required packages listed in the README were

installed\footnote{The ``dpkg'' command is a Debian-specific way of

  finding installed packages.}.

Next, the investigator then extracted the primary source package with the

following command:

\lstset{tabsize=2}

\begin{lstlisting}[language=bash]

$ tar --posix -jxpf libCMC/librecmc-v1.2.1.tar.bz2

\end{lstlisting}

The investigator did notice an additional source release, entitled

``librecmc-u-boot.tar.bz2''.  The investigator concluded upon simple

inspection that the instructions found in ``u-boot\verb0_0reflash'' were

specific instructions for that part of the CCS\@.  This was a minor

annoyance, and ideally the ``README'' would so-state, but the CCS filesystem

layout met the reasonableness standard; the skilled investigator determine the correct

course of action with a few moments of study.

The investigator then noted the additional step offered by the ``README'',

which read:

\begin{quotation}

Please use ``make menuconfig'' to configure your appreciated configuration

for the toolchain and firmware. Please note that the default configuration is

what was used to build the firmware image for your router. It is advised that

you use this configuration.

\end{quotation}

This instruction actually exceeds GPL's requirements.

Specifically, the instruction guides users in their first step toward

exercising the freedom to modify the software.  While the GPL does contain

requirements that facilitate the freedom to modify (such as ensuring the CCS is

in the ``preferred form \ldots for making modifications to it''), GPL

does not require specific instructions explaining how to undertake

modifications.  This specific instruction therefore exemplifies

the exceptional quality of this particular CCS\@.

%FIXME: add a \hyperref to some ``preferred for for modification'' stuff above.

However, for purposes of the CCS verification process, typically the

investigator avoids any unnecessary changes to the source code during the

build process, lest the investigator err and cause the build to fail through

his own modification, and thus incorrectly identify the CCS as inadequate.

Therefore, the investigator proceeded to simply run:

\lstset{tabsize=2}

\begin{lstlisting}[language=bash]

$ cd libCMC

$ make

\end{lstlisting}

and waited approximately 40 minutes for the build to complete\footnote{Build

  times will likely vary widely on various host systems.}.  The investigator

kept a

\href{https://gitorious.org/copyleft-org/tutorial/source/master:enforcement-case-studies_log-output/thinkpenguin_librecmc-complete.log}{full

  log of the build}, which is not included herein due its size (approximately

7.2K of text).

\label{thinkpenguin-main-build}

Upon completion of the ``make'' process, the investigator immediately found

(almost to his surprise) several large firmware files in the ``bin/ar71xx''

directory.  Typically, this step in the CCS verification process is

harrowing.  In most cases, the ``make'' step will fail due to a missing

package or because toolchain paths are not setup correctly.

In light of such experiences, the investigator speculated that ThinkPenguin's engineers did

the most important step in self-CCS verification: test one's own instructions

on a clean system.  Ideally, an employee with similar skills but

unfamiliar with the specific product can most easily verify CCS  and identify

problems before a violation occurs.

% FIXME: Is there stuff about the above in the compliance guide?  If so, link

% to it.  If not, write it, then link to it. :)

However, upon completing the ``make'', the investigator was unclear which

filesystem and kernel images to install on the TPE-NWIFIROUTER hardware.

Ideally, the original ``README'' would indicate which image is appropriate

for the included hardware.  However, this was ultimately an annoyance rather

than a compliance issue.  Fortunately,

the web UI (see next section) on the TPE-NWIFIROUTER performs firmware image

installation.  Additionally, the router's version number was specified on the

bottom of the device, which indicated which of the differently-versioned images

we should install.  The investigator would prefer instructions such as

those found at

\url{http://librecmc.org/librecmc/wiki?name=Tp+MR3020}{instructions similar

  to these} in the README itself; however, application of the reasonableness

standard here again indicates compliance, since a knowledgeable user can easily

determine the proper course of action.

\section{U-Boot Compilation}

%FIXME: link to u-boot reflash, maybe put it in log-output dir?

The investigator then turned his attention to the file,

``u-boot\verb0_0reflash''.  These instructions explained how to

build and install the bootloader for the device.

The investigator followed the instructions for compiling U-Boot, and found

them quite straight-forward.  The investigator discovered two minor

annoyances, however, while building U-Boot:

\begin{itemize}

 \item The variable \verb0$U-BOOT_SRC0 was used as a placeholder for the name

   of the extracted source directory.  This was easy to surmise and was not a

   compliance issue (per the reasonableness standard), but explicitly stating

   that fact at the top of the instructions would be helpful.

\label{thinkpenguin-glibc-214-issue}

\item Toolchain binaries were included and used by default by the build

  process.  These binaries were not the appropriate ones for the

  investigator's host system, and the build failed with the following error:

\lstset{tabsize=2}

\begin{lstlisting}

mips-librecmc-linux-uclibc-gcc.bin: /lib/libc.so.6:

   version `GLIBC`_2.14' not found

   (required by mips-librecmc-linux-uclibc-gcc.bin)

\end{lstlisting}

   (The

\href{https://gitorious.org/copyleft-org/tutorial/source/master:enforcement-case-studies_log-output/thinkpenguin_u-boot-build_fail.log}{complete

  log output from the failure} is too lengthy to include herein.)

   This issue is an annoyance, not a compliance problem.  It was clear from

   context that these binaries were simply for a different host architecture, and

   the investigator simply removed ``toolchain/bin'' and created a symlink to

   utilize the toolchain already built earlier (during the compilation

   discussed in \S~\ref{thinkpenguin-main-build}):

\lstset{tabsize=2}

\begin{lstlisting}

$ ln -s \

  ../../staging_dir/toolchain-mips_34kc_gcc-4.6-linaro_uClibc-0.9.33.2/bin \

  toolchain/bin

\end{lstlisting}

   After this change, the U-Boot build completed successfully.

\end{itemize}

The

\href{https://gitorious.org/copyleft-org/tutorial/source/master:enforcement-case-studies_log-output/thinkpenguin_u-boot-finish_build.log}{full

  log of the build} is not included herein due its size (approximately 3.8K

of text).  After that, the investigator found a new U-Boot image in the

``bin'' directory.

\section{Root Filesystem and Kernel Installation}

The investigator next tested installation of the firmware.  In particular,

the investigator connected the TPE-NWIFIROUTER to a local network, and

visited \url{http://192.168.10.1/}, logged in, and chose the option sequence:

``System $\Rightarrow$ Backup / Flash Firmware''.

From there, the investigator chose the ``Flash new firmware image'' section

and selected the

``librecmc-ar71xx-generic-tl-wr841n-v8-squashfs-sysupgrade.bin'' image from

the ``bin/ar71xx'' directory.  The investigator chose the ``v8'' image upon

verifying the physical router read ``v8.2'' on its bottom.  The investigator

chose the ``sysupgrade'' version of the image because this was clearly a

system upgrade (as a firmware already came preinstalled on the

TPE-NWIFIROUTER).

Upon clicking ``Flash image\ldots'', the web interface prompted the

investigator to confirm the MD5 hash of the image to flash.  The investigator

did so, and then clicked ``Proceed'' to flash the image.  The process took

about one minute, at which point the web page refreshed to the login screen.

Upon logging in, the investigator was able to confirm in the ``Kernel Log''

section of the web interface that the newly built copy of Linux had indeed been

installed.

The investigator confirmed that a new version of ``busybox'' had also been

installed by using SSH to connect to the router and ran the command

``busybox'', which showed the newly-compiled version (via its date of

compilation).

%FIXME: dg: can you get me  a screen shot for the Kernel Log above, and paste

%in the output of running busybox ?

%FIXME: bkuhn: the screen shot for the Kernel Log is in the log output dir at

%thinkpenguin_librecmc-built-kernel_log.png and the BusyBox output is in the

%same directory at thinkpenguin_librecmc-built-busybox_output.log - you may want

%to only use part of the BusyBox output (maybe even just the login) for brevity

\section{U-Boot Installation}

The U-Boot installation process is substantially more complicated than the

firmware update.  The investigator purchased the optional serial cable

along with the TPE-NWIFIROUTER, in order to complete the U-Boot installation

per the instructions in ``u-boot\verb0_0reflash'' in its section ``Installing

u-boot to your router'', which reads:

\begin{quotation}

  \begin{enumerate}

    \item Install and configure any TFTP server on your PC (tftp-hpa).

       Set a fixed IP address on your PC \ldots and connect it to the router,

       using RJ45 network cable \ldots

 \item Connect USB to UART adapter to the router and start any application to

   communicate with it, like PuTTY. \ldots

   \item Power on the router, wait for a line like one of the following and

     interrupt the process of loading a kernel:

\begin{verbatim}

 Autobooting in 1 seconds

      (for most TP-Link routers, you should enter tpl at this point)

Hit ESC key to stop autoboot: 1 (for 8devices Carambola 2, use ESC key)

 Hit any key to stop autoboot: 1 (for D-Link DIR-505, use any key)

\end{verbatim}

\item   Set ipaddr and serverip environment variables:

\lstset{tabsize=2}

\begin{lstlisting}

    hornet> setenv ipaddr 192.168.1.1

    hornet> setenv serverip 192.168.1.2

\end{lstlisting}

  \end{enumerate}

\end{quotation}

%FIXME: image of the serial cable available anywhere to put here:

%  https://www.adafruit.com/images/970x728/954-02.jpg

The investigator used the purchased serial cable, which was a USB serial

adapter with a male USB type A connector to 4 female jumper wires.  The

female jumper wires were red, black, white, and green.

The instructions here were slightly incomplete, since they did not specify

how to connect the wires to the router.  However, the investigator found

general information available online at

\url{http://wiki.openwrt.org/toh/tp-link/tl-wr841nd#serial.console} which

described the proper procedure.  While the ``power'' and ``ground'' cables

were obvious, some trial and error was necessary to find the RX and TX

cables, but this was easily determined since miswiring TX and RX yields no

I/O and proper wiring yields the output as expected.  Using the pin gender

changer included with the adapter, the investigator was able to stably wire

the pins for use once the proper RX and TX connections were determined.

The investigator then used the recommended 115200 8N1 for serial console

settings, leaving all flow control off, and tested both with the

\verb0minicom0 and \verb0screen0 commands.  The investigator found that if

all 4 wires were connected on the USB serial adapter that the router would

start without additional power and the console would receive the startup

messages.  The investigator could replicate the same behavior by omitting the

power cable from the USB serial adapter (red wire) and connecting the main

power adapter to the router instead.

At this point, the on-screen messages as described in the installation

instructions appeared, but the investigator found that no key events sent via

the serial port appeared to reach the U-Boot console.  In other words, while

the investigator saw both U-Boot and kernel boot messages in the serial

console, the investigator was unable to interrupt the boot process as

instructed by ``u-boot\verb0_0reflash''.  Hitting a key simply did

\textit{not} interrupt the boot process and yield the \verb0hornet>0 prompt.

After additional trial and error over a period of hours, the investigator had

finally to consider this question for the first time during the process:

``Has ThinkPenguin violated the GPL?'' More specifically, the immediate

question was: ``Given this failure, has the distributor met

\hyperref[GPLv2s3-build-scripts]{the requirements for `scripts used to

  control \ldots installation of the executable' (GPLv2)} and

\hyperref[GPLv3-installation-information]{necessary `Installation

  Information' (GPLv3)}?''

The appropriate answer to the question (at this specific stage) is ``possibly,

but more information is needed''.  Embedded installation and configuration is

a tricky and complex technical process.  While the GPL requires documentation

and clear instructions for this process, the investigator did not immediately blame the distributor

for what may be an honest, correctable mistake, or an issue legitimately explained by

feasible alternative theories.

In this case, upon remembering the issues of wiring, the investigator wonder

if perhaps the power pin was accidentally connected for a moment to the RX

pin while live.  Such action could easily fry the RX pin, and yield the

observed behavior.  Since the investigator could not rule out the possibility

of accidental connection of power to the RX pin mentioned, the investigator

had to assume the instructions would work properly if he had not made that

error.

That conclusion, while correct, also left the investigator with only two

option to complete the final verification of the CCS:

\begin{itemize}

   \item Purchase a new router and cable anew, and reattempt the installation

     process while taking extra care not to miswire any cables.

   \item Seek assistance from the libreCMC community to find an alternative

     method of installation.

\end{itemize}

The investigator chose the latter and then contacted a libreCMC developer

familiar with the product.  That developer, who  agreed the the RX pin was

likely ruined, described an alternative method for console access using the

{\tt netcat}.  The libreCMC developer described the process as follows:

\begin{quotation}

  \begin{itemize}

  \item Change the IP address of the router to 192.168.1.1.

  \item Change the IP address of a desktop GNU/Linux system to 192.168.1.2.

  \item Power on the router while holding the reset button for 7 seconds.

  \item Use the {\tt netcat} command (as below) on the desktop, and press

    enter to receive U-Boot's prompt:

\lstset{tabsize=2}

\begin{lstlisting}[language=bash]

$ nc -u -p 6666 192.168.1.1 6666

uboot>

\end{lstlisting}

  \end{itemize}

\end{quotation}

Upon following this procedure, the investigator was able to confirm the

(original) shipped version of U-Boot was still installed:

\begin{lstlisting}[language=bash]

$ nc -u -p 6666 192.168.1.1 6666

uboot> version

U-Boot 1.1.4 (Jul 28 2014)

\end{lstlisting}

Thereafter, the investigator followed the instructions from

``u-boot\verb0_0reflash''.  Specifically, the investigator configured a TFTP server

and placed the newly built firmware into \texttt{/srv/tftp}.  The investigator

also followed the remaining instructions in ``u-boot\verb0_0reflash'', but

used the \texttt{netcat} console rather than the serial console, and

used U-Boot's \texttt{reset} command to reboot the router.

Upon reboot, the serial console (still connect with working output) showed

the message \texttt{U-Boot 1.1.4  (Oct 17 2014)}, and thus confirmed a

successful reflash of the U-Boot image built by the investigator.

\section{Firmware Comparison}

Next, to ensure the CCS did indeed correspond to the firmware original

installed on the TPE-NWIFIROUTER, the investigator compared the built

firmware image with the filesystem originally found on the device itself.

The comparison steps were as follows:

\begin{enumerate}

\item Extract the filesystem from the image we built by running

  \href{https://gitorious.org/copyleft-org/gpl-compliance-scripts/source/master:find-firmware.pl}{find-firmware.pl}

  on ``bin/ar71xx/librecmc-ar71xx-generic-tl-wr841n-v8-squashfs-factory.bin''

  and then running

  \href{http://www.binaryanalysis.org/en/content/show/download}{bat-extratools}'

  ``squashfs4.2/squashfs-tools/bat-unsquashfs42'' on the resulting

  morx0.squash, using the filesystem in the new squashfs-root directory for

  comparison.

\item Login to the router's web interface (at \url{http://192.168.10.1/ }) from a computer

  connected to the router.

\item Set a password using the provided link at the top (since the router's

  UI warns that no password is set and asks the user to change it).

\item Logged into the router via SSH, using the root user with the

  aforementioned password.

\item Compared representative directory listings and binaries to ensure the set of

  included files (on the router) is similar to those found in the firmware

  image that the investigator created (whose contents are now in the local squashfs-root directory).  In

  particular, the investigator did the following comparisons:

  \begin{enumerate}

  \item Listed the /bin folder (``ls -l /bin'') and confirm the list of files is the same

    and that the file sizes are similar.

  \item Checked the ``strings'' output of ``/bin/busybox'' to confirm it is similar in both

   places (similar number of lines and content of lines).  (One cannot directly

   compare the binaries because the slight compilation variations will cause

   some bits to be different.)

 \item Repeated the above two steps for ``/lib/modules'', ``/usr/bin'', and other directories with

   a significant number of binaries.

 \item Checked that the kernel was sufficiently similar.  The investigator

   compared the ``dmesg'' output both before and after flashing the new

   firmware.  As the investigator expected, the kernel version string was

   similar, but had a different build date and user@host indicator.  (The

   kernel binary itself is not easily accessible from an SSH login, but was

   retrievable using the U-Boot console (the start address of the kernel in

   flash appears to be 0x9F020000, based on the boot messages seen in the

   serial console).

  \end{enumerate}

\end{enumerate}

\section{Minor Annoyances}

As discussed in detail above, there were a few minor annoyances, none of

which were GPL violations.  Rather, the annoyances briefly impeded the

build and installation.  However, the investigator, as a reasonably skilled

build engineer for embedded devices, was able to complete the process with

the instructions provided.

To summarize, no GPL compliance issues were found, and the CCS release was

one of the best ever reviewed by any investigator at any community-oriented

enforcement organization.  However, the following annoyances were discovered:

\begin{itemize}

\item Failure to explain how to extract the source tarball and then where to run the

  ``make'' command.

\item Failure to explain how to install the kernel and root filesystem on the

  device; the user must assume the web UI must be used.

\item Including pre-built toolchain binaries that don't work on all systems,

  and failure to copy and/or symlink built toolchain binaries in the right location.

\item Failure to include information in the U-Boot installation instructions for

  wiring the serial cable.

\item Ideally, the U-Boot installation instructions would also include the

  {\tt netcat} method of installation.

\item Finally, the instructions should note that the new U-Boot firmware

  should be placed into \texttt{/srv/tftp} when using TFTP on most GNU/Linux

  desktops.

\end{itemize}

Thus, no CCS is absolutely perfect, but GPL violation investigators always

give the distributors the benefit of any doubts and seek to work with the

vendors and improve their CCS for the betterment of their users, customers,

and the entire software freedom community.

\section{Lessons Learned}

Companies that seek to redistribute copylefted software can benefit greatly

from ThinkPenguin's example.  Here are just a few of the many lessons that

can be learned here:

\begin{enumerate}

\item Even though copyleft licenses have them,

  \hyperref[thinkpenguin-included-ccs]{\bf avoid the offer-for-source

    provisions}.  Not only does including the CCS alongside binary

  distribution make violation investigation and compliance confirmation

  substantially easier, but also (and more importantly) doing so

  \hyperref[offer-for-source]{completes the distributor's CCS compliance

    obligations at the time of distribution} (provided, of course, that the

  distributor is otherwise in compliance with the relevant copyleft license).

\item {\bf Include top-level build instructions in a natural language (such

  as English) in a \hyperref[thinkpenguin-toplevel-readme]{clear and

    conspicuous place}.}  Copyleft licenses require that someone reasonably

  skilled in the art can reproduce the build and installation.  Typically,

  instructions written in English are necessary, and often easier than writing

  programmed scripts.  The ``script'' included can

  certainly be more like the script of a play and less like a Bash script.

\item {\bf Write build/install instructions to the appropriate level of

  specificity}.  The upstream engineers

  in this case study \hyperref[thinkpenguin-specific-host-system]{clearly did

    additional work to ensure functionality on a wide variety of host build

    systems}; this is quite rare.  When in doubt, include the maximum level

  of detail build engineers can provide with the CCS instructions, but also

  double-check to investigate if a more generalized solution (such as other

  host systems) work just as well for the build.

\item {\bf Seek to adhere to the spirit of copyleft, not just the letter of

  the license}.  Encouragement of users to improve and

  make their devices better is one of ThinkPenguin's commercial differentiators.  Copyleft advocates

  that other companies have undervalued the large and lucrative

  market of

  users who seek hackable devices.  By going beyond the

  mere minimal requirements of GPL, companies can immediately reap the

  benefits in that target market.

  \item Community-oriented enforcement organizations do not play ``gotcha''\footnote{For lack of a better

    phrase.} with distributors regarding GPL

    violations.  The goal in the GPL enforcement process is to achieve

    compliance and correct mistakes and annoyances.  Such organizations

    due to honest error rather than malicious action '' approach.  The goal

    is compliance (in direct contrast with

    the \hyperref[Proprietary Relicensing]{discussion in \S~\ref*{Proprietary Relicensing} about the

      proprietary relicensing} business model).

\end{enumerate}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\chapter{Bortez: Modified GCC SDK}

In our first case study, we will consider Bortez, a company that

produces software and hardware toolkits to assist OEM vendors, makers

of consumer electronic devices.

\section{Facts}

One of Bortez's key products is a Software Development Kit (``SDK'')

designed to assist developers building software for a specific class of

consumer electronics devices.

FSF received a report that the SDK may be based on the GNU Compiler

Collection (which is an FSF-copyrighted collection of tools for software

development in C, C++ and other popular languages). FSF investigated the

claim, but was unable to confirm the violation. The violation reporter

was unresponsive to follow-up requests for more information.

Since FSF was unable to confirm the violation, we did not pursue it any

further. Bogus reports do happen, and we do not want to burden companies

with specious GPL violation complaints. FSF shelved the matter until

more evidence was discovered.

FSF was later able to confirm the violation when two additional reports

surfaced from other violation reporters, both of whom had used the SDK

professionally and noticed clear similarities to FSF's GNU GCC\@. FSF's

Compliance Engineer asked the reporters to run standard tests to confirm

the violation, and it was confirmed that Bortez's SDK was indeed a

modified version of GCC\@. Bortez had ported to Windows and added a number

of features, including support for a specific consumer device chipset and

additional features to aid in the linking process (``LP'') for those

specific devices. FSF explained the rights that the GPL afforded these

customers and pointed out, for example, that Bortez only needed to provide

source to those in possession of the binaries, and that the users may need

to request that source (if \S 3(b) was exercised). The violators

confirmed that such requests were not answered.

FSF brought the matter to the attention of Bortez, who immediately

escalated the matter to their attorneys. After a long negotiation,

Bortez acknowledged that their SDK was indeed a modified version of

GCC\@. Bortez released most of the source, but some disagreement

occurred over whether LP was also derivative of GCC\@. After repeated

FSF inquiries, Bortez reaudited the source to discover that FSF's

analysis was correct. Bortez determined that LP included a number of

source files copied from the GCC code-base.

\label{davrik-build-problems}

Once the full software release was made available, FSF asked the violation

reporters if it addressed the problem. Reports came back that the source

did not properly build. FSF asked Bortez to provide better build

instructions with the software, and such build instructions were

incorporated into the next software release.

At FSF's request as well, Bortez informed customers who had previously

purchased the product that the source was now available by announcing

the availability on its Web site and via a customer newsletter.

Bortez did have some concerns regarding patents. They wished to include a

statement with the software release that made sure they were not granting

any patent permission other than what was absolutely required by the GPL\@.

They understood that their patent assertions could not trump any rights

granted by the GPL\@. The following language was negotiated into the release:

\begin{quotation}

Subject to the qualifications stated below, Bortez, on behalf of itself

and its Subsidiaries, agrees not to assert the Claims against you for your

making, use, offer for sale, sale, or importation of the Bortez's GNU

Utilities or derivative works of the Bortez's GNU Utilities

(``Derivatives''), but only to the extent that any such Derivatives are

licensed by you under the terms of the GNU General Public License. The

Claims are the claims of patents that Bortez or its Subsidiaries have

standing to enforce that are directly infringed by the making, use, or

sale of an Bortez Distributed GNU Utilities in the form it was distributed

by Bortez and that do not include any limitation that reads on hardware;

the Claims do not include any additional patent claims held by Bortez that

cover any modifications of, derivative works based on or combinations with

the Bortez's GNU Utilities, even if such a claim is disclosed in the same

patent as a Claim. Subsidiaries are entities that are wholly owned by

Bortez.

This statement does not negate, limit or restrict any rights you already

have under the GNU General Public License version 2.

\end{quotation}

This quelled Bortez's concerns about other patent licensing they sought to

do outside of the GPL'd software, and satisfied FSF's concerns that Bortez

give proper permissions to exercise teachings of patents that were

exercised in their GPL'd software release.

Finally, a GPL Compliance Officer inside Bortez was appointed to take

responsibility for all matters of GPL compliance inside the company.

Bortez is responsible for informing FSF if the position is given to

someone else inside the company, and making sure that FSF has direct

contact with Bortez's Compliance Officer.

\section{Lessons}

This case introduces a number of concepts regarding GPL enforcement.