Subject: Re: LGPL... variations on a theme
From: "Stephen J. Turnbull" <turnbull@sk.tsukuba.ac.jp>
Date: Fri, 6 Jul 2001 18:56:36 +0900

>>>>> "Bernard" == Bernard Lang <Bernard.Lang@inria.fr> writes:

    Bernard> I do not understand ... it looks to me that a modified
    Bernard> version of the library will inherit the libgcc exception,
    Bernard> and be linkable as well.

Any modification to libgcc reverts the license on libgcc to GPL.  This
implies that if your version of GCC contains a modified libgcc, _all
programs compiled with it in the normal way become subject to the
GPL_.  This isn't what RMS had in mind (he wanted _running gcc_ to be
free of licensing implications), so the exception is necessary.

Similar exceptions are necessary for Bison.  The historical note on
licensing ("Conditions" from the menu for "info Bison", short, but
will help clarify I think) indicates that RMS was more reluctant in
this case.  I'm not sure why, in principle it's the same I should
think.  I suppose it has to do with the fact that the "helper
functions" in libgcc are mostly completely obvious, while yyparse()
from bison (which gets included in every program that uses a bison
parser) is "real code".

    Bernard> isn't the libgcc exception license more liberal than the
    Bernard> LGPL ?

See above.

    >> Is it possible for them to release the library as a shared
    >> library?  That would let them use the unmodified LGPL.

    Bernard> apparently that is not easy

Embedded systems come to mind.  If everything runs out of ROM, what
does "dynamic linking" mean?  ;-)

Anyway, the library will be released as _source_; the modifications to
turns something designed as a DLL into something statically linkable
can't be tough.

    Bernard> Is [the libgcc exception] much used ?

Well, libgcc is referenced in the link command almost every time a
non-GPL binary built with gcc is distributed.  I don't know how often
those functions in libgcc are used, but surely neither do most of the
non-GPL developers (including the *BSD people, whose software is all
built with GCC!!)

But that's exactly the saving that your clients are aiming at.


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