Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3

From: Bernd Paysan
Date: Fri Jun 15 2007 - 05:30:29 EST

On Friday 15 June 2007 01:46, david@xxxxxxx wrote:
> if you cannot modify the software that runs on your Tivo hardware you
> haven't tried very hard.

Yes, but the GPLv2 clearly says that you don't have to try very hard. The
preferred form of modification has to be distributed. I can run a
decompiler or disassembler on a program, and I can even modify it in place
with a hex editor (I have even modified programs in embedded ROMs by using
focussed ion beam, so I know you can modify every program if you try hard
enough). It's certainly possible to crack Tivo's firmware to accept my own
signature, but it's *not* the preferred form of modification, the source
code and Tivo's key for the signature.

Since Tivo's firmware only accepts a signed kernel, the combination of
kernel+signature is the binary they ship. The kernel itself is useless, the
signature as well. Therefore, you can imply that Tivo's key is part of
the "other stuff" the GPLv2 mentions, because you need it to recreate the
same code as Tivo did and shipped (compilers insert timestamps and such),
and to modify that code. The source code is just a mean, the thing they
shipped is the end (the binary), and they have to comply with the GPL for
that binary - which by all means of practical understanding includes the

"You can imply" means: It depends on court and legal system. I'm quite
confident that in Germany, the legal system might favor the "GPLv2 does not
allow tivoization" point of view, and in the USA, the legal sysem might do
the opposite.

Bernd Paysan
"If you want it done right, you have to do it yourself"

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