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Denver Gingerich - 10 years ago 2014-11-07 21:58:26
denver@ossguy.com
Fix typos/grammar in "U-Boot Compilation" sec on
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enforcement-case-studies.tex
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@@ -181,677 +181,678 @@ 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, we offer a study in how copyleft compliance can 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, the CCS
 
release describes the first one CCS experts have 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 fix the description of
 
``barely complies 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\@}, electronics products have begun to appear on the market that are
 
  CCS\@.}, electronics products have begun to appear on the market that are
 
held to 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.
 
Specifically, this chapter discusses the purchase, CCS provision, and a
 
step-by-step build and installation analysis of a specific, physical,
 
embedded electronics product.  The product in question is
 
\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 the certification process.
 
  The analysis discussed herein was independently performed by Software
 
  Freedom Conservancy without reviewing any findings of the FSF, and thus the
 
  analysis provides a ``true to form'' analysis as it occurs when Conservancy
 
  investigates 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
 
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 here 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} in this guide, and had chosen to use
 
\hyperref[GPLv2s3a]{GPLv2\S3(a)} and \hyperref[GPLv3s6]{GPLv3s6}, rather than
 
using the \hyperref[offer-for-source]{problematic offer for source
 
  provisions}.  This choice not only speeds up the investigation (since there
 
is no CCS offer to test), but also simplifies 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 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 by
 
studying the contents of the ``README'', which contained the appropriate
 
details to get started with a 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 in building
 
testing this CCS candidate was the above, which ran on the investigator's own
 
brain --- like a script of a play.  Less glibly, instructions written in
 
English are particularly necessary for parts of the build and installation
 
process that require some amount of actual intelligence to complete.
 
In this case, the investigator was able to determine the requirements for the
 
host system to use when constructing the firmware for the embedded device.
 

	
 
GPL does not, of course, give specific guidance on the form or location of
 
such instructions.  Community-oriented GPL enforcers generally use 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.  However, in this case, the
 
instructions are more abundant and give more detail.
 

	
 
These instructions are more general than typical.  Often, top-level build
 
instructions will specifically name a host distribution to use, such as
 
``Debian 7 installed on an amd64 system with the following packages
 
installed''.  If the build will not complete on any other system,
 
instructions should have such details.  However, in this case, the CCS can
 
build on a wide range of distributions, and thus no specific distribution was
 
specified.
 

	
 
\label{thinkpenguin-specific-host-system}
 

	
 
In this specific case, the developers of the libreCMC project (on which the
 
TPE-NWIFIROUTER is based) 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.   Even in this case, a
 
\hyperref[thinkpenguin-glibc-214-issue]{minor annoyance was found that more
 
  detailed instructions would address}.
 

	
 
Anyway, since these instructions did not specify a specific host system, the
 
investigator simply used his own amd64 Debian 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 list that fact, but the existing
 
layout met the reasonable standard that community-oriented GPL enforcers
 
typically apply, since the skilled investigator could 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 goes above and beyond the requirements of GPL\@.
 
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'' form), it
 
does not require that you write specific instructions explaining how
 
modifications might be undertaken.  This 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
 
  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.
 

	
 
From experience, the investigator is sure that ThinkPenguin's engineers did
 
the most important step in self-CCS verification: use 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 due to other information available.  Specifically,
 
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.  It would be ideal to find
 
\href{http://librecmc.org/librecmc/wiki?name=Tp+MR3020}{instructions similar
 
  to these} in the README itself.  However, application of the reasonableness
 
standard indicates compliance, since a knowledgeable user was able to
 
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'' instructions.  These instructions explained how to
 
build and install the bootloader for the device.
 

	
 
The investigator followed the instructions for compiling u-Boot, and found
 
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
 
 \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 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 architecture, and
 
   the investigator simply removed ``toolchain/bin'' and used a symlink the
 
   the investigator simply removed ``toolchain/bin'' and used 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 ``Kernel Log''
 
section of the 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 ?
 

	
 
%% \section{U-Boot Installation}
 

	
 
%% The U-Boot installation process is substantially more complicated than the
 
%% firmware update.  The investigator purchased the optional a serial cable
 
%% along with the TPE-NWIFIROUTER, in order to complete the U-Boot installation
 
%% per the instructions in'' -boot\verb0_0reflash''.
 

	
 
%% However, we were
 
%% only able to read data from the serial port; we were unable to interrupt the
 
%% boot process or access the U-Boot console to complete the U-Boot re-flash.  Here
 
%% are the steps we tried:
 

	
 
%% * We found the serial cable included was a USB serial adapter that had a male
 
%%   USB type A connector on one end and 4 female jumper wires at the other end.
 
%%   These female jumper wires were red, black, white, and green.
 
%% * The instructions did not specify how to connect these wires, but we were able
 
%%   to determine this in part using the "v8.4" image (close to our "v8.2" router)
 
%%   at \url{http://wiki.openwrt.org/toh/tp-link/tl-wr841nd#serial.console} .  Aside from
 
%%   power and ground (red and black), we did have to guess which of the wires was
 
%%   RX and TX.  By experimentation we found that green was RX and white was TX.
 
%%   When we tried the other way, we received no data to our serial console at boot
 
%%   time.
 
%% * We did have to use the included jumper pin gender changer with the USB serial
 
%%   adapter, which we put through the holes on the router's mainboard and then
 
%%   connected to the USB serial adapter.  The fit was fairly loose so it would be
 
%%   nice if future router versions included a tighter gender changer or (ideally)
 
%%   had the jumper pins soldered onto the board to begin with (so no gender
 
%%   changer would be required).
 
%% * We used 115200 8N1 as our serial console settings (with no hardware or
 
%%   software flow control).  This was tested with both the minicom and screen
 
%%   commands.  We found that if we connected all 4 wires on the USB serial adapter
 
%%   that the router would start without additional power and our console would
 
%%   receive the startup messages.  We 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.
 
%% * While we did see the U-Boot and kernel boot logs in our serial console, we
 
%%   were unable to interrupt the boot process as u-boot\verb0_0reflash indicated we
 
%%   should.  We suspect this is a misconfiguration of our serial console, but it's
 
%%   unclear exactly how it is misconfigured, as we were able to receive data fine
 
%%   (we just couldn't send data to the router).
 
%% * As a result, we were unable to complete the U-Boot installation test.  We did
 
%%   appreciate that installation instructions were included, though these
 
%%   instructions should be updated to include more specifics about connecting the
 
%%   serial cable.  Since ThinkPenguin does have the option to ship a serial
 
%%   adapter with the router, it would be helpful if instructions specific to that
 
%%   adapter were included, as the wiring configuration one should use was unclear.
 
%% * Additionally, instructions for removing the router's case should be included.
 
%%   We found that the two screws that needed removal to open the case were hidden
 
%%   underneath rubber feet on the case.  Indicating which feet need removal to
 
%%   unscrew the case would be helpful.  The instructions should also note that the
 
%%   case needs to be carefully separated once the screws are removed; it
 
%%   effectively snaps apart, but care must be taken to avoid breaking the plastic
 
%%   fasteners that keep the case together after the screws are removed.
 

	
 
\section{Firmware Comparison}
 

	
 
To ensure that CCS did corresponds properly to the firmware original
 
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 we as follows:
 
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''
 
  bottom), and running
 
  and then running
 
  \href{http://www.binaryanalysis.org/en/content/show/download}{bat-extratools}'
 
  ``squashfs4.2/squashfs-tools/bat-unsquashfs42'' (at ) on the resulting
 
  morx0.squash and use the filesystem in the new squashfs-root directory for
 
  ``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 that is
 
  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 Login to the router via SSH, using the root user with the
 
  aforementioned password.
 
  
 
\item Compare representative directory listings and binaries to ensure the set of
 
  included files (on the router) is similar to those found in the firmware image
 
  we created (whose contents are now in the local squashfs-root directory).  In
 
  particular, we did the following comparisons:
 

	
 
  \begin{enumerate}
 
  \item List the /bin folder (``ls -l /bin'') and confirm the list of files is the same
 
    and that the file sizes are similar.
 
    
 
  \item Check the ``strings'' output of ``/bin/busybox'' to confirm it was similar in both
 
  \item Check 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 Do the above two steps for ``/lib/modules'', ``/usr/bin'', and other directories with
 
   a significant number of binaries.
 
   
 
 \item Check that the kernel is 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 0x9F000000, based on the ``u-boot\verb0_0reflash''
 
   instructions).
 
   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 an investigator.  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 built  toolchain binaries to the right location.
 
  and failure to put built toolchain binaries in the right location.
 
\end{itemize}
 

	
 
\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 more importantly it also
 
  \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 copyleft.
 
  distributor is otherwise in compliance with copyleft).
 
  
 
\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 your work.  Ultimately, sometimes
 
  instructions written in English are necessary, and often easier than trying
 
  to write programmed scripts to do everything.  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.
 

	
 
\item {\bf Seek to adhere to the spirit of copyleft, not just the letter of
 
  the license}.  ThinkPenguin uses encouragement of  users to improve and
 
  make their devices better as commercial differentiator.  Copyleft advocates
 
  remain baffled why other companies have not realized how large the market for
 
  make their devices better as a commercial differentiator.  Copyleft advocates
 
  remain baffled as to why other companies have not realized how the large the
 
  market for
 
  users who seek hackable devices continues to grow.  By going beyond the
 
  mere minimal requirements of GPL, companies can immediately reap the
 
  benefits in that target market.
 
  
 
\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.
 

	
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