Linux and embedded systems are a natural combination. Linux provides the
level of control and ability to customize that embedded vendors need; it
can also be pared down into a (relatively) small footprint. And, of
course, there are no per-unit royalties to be paid; that is a big deal for
many applications. It is not surprising that an increasing number of
gadgets have a Linux kernel running inside them.
Much of the code running in those systems is licensed under the GPL. While
no royalties need be paid for the distribution of GPL-licensed code, there
are other obligations which must be met. In particular, a Linux-powered
gadget is supposed to come with either (1) a copy of the source for
the code running inside, or (2) a written offer to ship the source
anytime in the next three years. While some companies (e.g. TiVo) make their source
available, it would seem that some other embedded system
vendors are forgetting about this obligation when they ship their boxes.
Recently, Andrew Miklas noticed that
his Linksys WRT54G wireless access point was running GPL-licensed software,
including a 2.4.5 kernel and the BusyBox tool suite. The product
contains no source, offer of source, or even acknowledgement of the GPL
software running inside. Attempts to obtain source from Linksys have, so
far, been unsuccessful. The Free Software Foundation is now taking an
interest in this case.
Linksys, it seems, is not alone in this behavior. Products from Belken,
Buffalo Technology, and QLogic have also been shown to have Linux inside,
with no source forthcoming. Lest one despair completely, however, it's
worth looking at Colm MacCárthaigh's
experience with his Dell TrueMobile 1184 router. Not only was he able
to (eventually) get the source from Dell; his efforts also convinced Dell
to include a source CD with the product.
Mr. MacCárthaigh's experience is worth noting for a couple of reasons. The
first is that Dell was simply unaware that it was supposed to make source
available. In most GPL violation cases, the real problem is that the
company involved is unaware of its obligations under the license; GPL
violations tend to be unintentional. With some persistence - and
politeness - it is usually possible to get these companies to move into
compliance with the GPL. The Free Software Foundation has been very good
at this in the past; in contrast with its loudness on other fronts, the FSF
treats GPL problems with discretion and tact. As a result, most GPL
violators are brought around to compliance without being pushed into
full-scale defensive lockdown.
The other thing to note is that Mr. MacCárthaigh did not get anything all
that exciting for his efforts: a stock 2.2.14 kernel with a
widely-available patch set. In the Linksys case, many Linux users are
getting worked up about the prospect of extracting a new set of wireless
network drivers by forcing a release of code. These users will almost
certainly be disappointed. The drivers in question will be implemented as
loadable modules which, until some disgruntled kernel developer proves
otherwise in court, are legal to distribute for use with the kernel.
Linksys owes its customers the source for its Linux kernel, BusyBox, and
any other GPL software that it includes in its product. But it is under no
obligation to open up any proprietary drivers that it is using.
The truly sad part is that embedded system vendors need not even provide
source which can be rebuilt and loaded into their devices. As reported here in May, there appears to be no
legal impediment that can prevent systems vendors from requiring kernels to
be signed by a private key before they can be run. You can look at what
your Linux-powered device is running (if you trust the vendor to provide
the true source for the binaries in the box), but you may not be able to
Even so, it is important that distributors of GPL-licensed software live up
to the obligations imposed by that license. There is a vast body of highly
capable software which is available under the GPL, and all that's required
to be able to use it is to make the source available under the same
license. That is a small price to pay for free (of charge) access to software
that, by some estimates, is
worth over a billion dollars.
Update: since this article was first published, Linksys has stated that it will release the
source for the GPL-licensed code running in the WRT54G router.
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