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

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 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 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 ?

%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{Firmware Comparison}

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 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 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 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 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).

\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 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}