Issues with rtl_tcp

Sylvain Munaut 246tnt at gmail.com
Wed Sep 26 19:52:23 UTC 2012


Hi,


> "Once this change is made in a given copy, it is irreversible
> for that copy, so the ordinary GNU General Public License
> applies to all subsequent copies and derivative works made
> from that copy."
>
> I am not a lawyer, but it seems to me that this statement
> implicates that the library license is more restricted and
> that things you are allowed to do under the library license
> are still allowed under the general license.

Clearly you're not. It's pretty much exactly the opposite actually.
LGPL is _LESS_ restrictive and among those additional freedom, you can
relicense it under GPL.


> In the library license we can read this:
>  [snip]

> This means you are free to use the rtlsdr dll available
> at osmocom but you can not distribute an executable in
> which the library is linked in.

??? How exactly did you go from taking a software distributed using
GPL (rtl-sdr and librtlsdr) and just apply LGPL clauses to it ???

As said above you can't do that at all.


> Likewise can I distribute Linrad under Linux and give
> the user the instructions how to link in librtl.so
> from the osmocom site or from a complete and somewhat
> modified version that I will supply myself in case
> the modifications to the library I will propose will not
> be accepted.

If you link to librtlsdr.so, you _have_ to be a GPL compatible license
and that's it. That's how GPL works.

Now, the only license I saw in linrad seems to be pretty much public
domain. So you _can_ link to librtlsdr.so directly without any issue.
Any distribution of binaries that are linked to it however will
effectively be GPL. But anyone is still completely free to take
whatever part of your public domain code and do whatever they want
with it. However if they also want to distribute binaries of their
modified code linked to rtlsdr, then they'll have to release those
under a GPL compatible license as well.

So there are no risk to you, anyone will still be free to extract your
sdr algorithm and use them however they want, according to your own
rules. Only the rtlsdr link will be conditional to GPL terms. For
example they'd be free to take your software, disable the rtlsdr part,
do some mods, and sell the resulting binaries.

Cheers,

     Sylvain




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