Add chapter on router with included source CD

Note that this chapter is not properly TeX-formatted.  Some work will
need to be done to make it compile correctly.  It should also be
generally expanded and made to flow more nicely, in the spirit of the
other case study chapters.
This commit is contained in:
Denver Gingerich 2014-10-18 18:49:39 -04:00
parent 4a40f09f14
commit 5c22a2b18c

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@ -798,6 +798,107 @@ Linux. A decade later, this situation remains largely unresolved.
\end{enumerate} \end{enumerate}
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% FIXME: expand title, etc.
\chapter{ThinkPengiun}
% FIXME
This case study discusses one the best source code releases we've seen, which
was provided alongside the ThinkPengiun TPE-NWIFIROUTER. The method of
distribution (complete source accompanying the product) and the way the source
was laid out provide very good examples of how to make things easier for both
the distributor and the purchaser of the hardware containing GPLed components.
\section{Root Filesystem and Kernel Compilation}
* We found a CD included in the box that the ThinkPenguin TPE-NWIFIROUTER
shipped in, labelled "libreCMC v1.2.1 source code". On the CD, there was a
README file at the top level, which mentioned that to build the software, one
needed a GNU/Linux system as well as a list of approximately 10 packages.
These sorts of plain text instructions are helpful because we know what kind
of system we are expected to use, and what commands we should run on it. Such
instructions are not strictly required, as an obviously-named shell script may
suffice, but they are helpful in clarifying any ambiguities that may arise.
* Since the instructions didn't mention a specific distro to use, we ran the
build on an amd64 Debian 6 machine we had, after confirming the packages were
installed. In particular, we ran "make", as described in the instructions in
the README. The instructions said that "make menuconfig" could be used to
adjust the settings, but it appeared this step was optional ("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.") so we chose to
skip straight to the "make" step instead. This was done after extracting the
librecmc-v1.2.1.tar.bz2 tarball, which was not explicitly spelled out (this
should ideally be added to the README), but was implied by the
"u-boot_reflash" file (in the same directory as the README), which explicitly
used the other tarball. The build took about 40 minutes to run on our system.
* It was helpful to know that we could use "make menuconfig" for configuration
changes, as being able to modify the source is an important part of the GPL's
requirements. Adding instructions like these shows that the distributor is
aware of and interested in promoting the spirit of the GPL, by making it
easier to modify the source than may be strictly required by the GPL's text.
* The "make" step completed successfully on our system and resulted in several
files being generated in the bin/ar71xx directory, namely firmware images.
There appeared to be several filesystem and kernel images, for different
hardware versions. It was unclear which one to install on the particular
device we received or how to install it, both of which should have been
mentioned in the README.
* The above installation issue is mitigated by the availability of a web UI in
the product that performs firmware image installation. It would be best if
instructions like those at http://librecmc.org/librecmc/wiki?name=Tp+MR3020
were included in the README, as the user cannot be expected to infer that or
to find such a link.
\section{U-Boot Compilation}
* As mentioned above, we also found a "u-boot_reflash" file at the top level of
the included source CD. We followed the instructions for compiling U-Boot,
which were fairly straight-forward. One modification would be to mention that
"\$U-BOOT_SRC" referred to the extracted source directory, which was implied,
but should have been explicit.
* Additionally, we noticed that the included toolchain binaries, which were used
by the U-Boot compilation process by default, did not run on our system. In
particular, we received this error:
mips-librecmc-linux-uclibc-gcc.bin: /lib/libc.so.6: version `GLIBC_2.14' not found (required by mips-librecmc-linux-uclibc-gcc.bin)
* We found that by removing toolchain/bin and symlinking the toolchain built for
the filesystem/kernel above in its place, we were able to complete the U-Boot
build. Specifically, we symlinked toolchain/bin to:
../../staging_dir/toolchain-mips_34kc_gcc-4.6-linaro_uClibc-0.9.33.2/bin
* Ideally the pre-built toolchain binaries should not be included and a symlink
as mentioned above should be created by default, with a mention that the
U-Boot build depends on the previous build for its toolchain.
* After compilation completed successfully, we found a new U-Boot image in the
bin directory. The instructions explained how to install it on the device.
\section{Installation}
% FIXME: add more details once install tests have been completed
\section{Minor Infractions}
As mentioned above, there were a few minor infractions. These made it slightly
difficult to complete the build and installation without additional context, but
did not make the build impossible to complete without more information, such as
missing source code for kernel modules or depending on a specific cross-compiler
but not mentioning which one or, better yet, including its source code, which
are both more problematic infractions. These minor infractions were:
% FIXME: clarify seriousness of no install instructions; lack of clarity in
% which version to install could be more problematic
* Not mentioning how to extract the source tarball and then where to run the
"make" command.
* Not mentioning how to install the kernel and root filesystem on the device;
this is the biggest of these 3 issues but a bit less troublesome than it would
otherwise have been since the web-based firmware update process is well-known.
* Using pre-built toolchain binaries that don't work on all systems instead of
the ones that are built in a separate step, but not moved to the right place.
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% COMMENT OUT THIS CHAPTER. % COMMENT OUT THIS CHAPTER.
% FIXME: is this material moot now that we include the compliance guide? % FIXME: is this material moot now that we include the compliance guide?