GPL vs BSD Licence

Ted Mittelstaedt tedm at
Thu Oct 28 23:22:44 PDT 2004

The GPL and Linux don't care if you link into their system libraries,
they expect that which is why the system libraries are LGPLd

What they care about is linking into libraries (like readline) which
they consider "their" work.  If you do it, regardless of whether you
use those library headers or use a translation think like you are
outlining here, you must GPL your stuff.

The contamination comes from linking in, even dynamically, not from
just using ascii source files.


> -----Original Message-----
> From: David Schwartz [mailto:davids at]
> Sent: Thursday, October 28, 2004 6:15 PM
> To: chat at
> Cc: TM4525 at; tedm at
> Subject: RE: GPL vs BSD Licence
> >   But then, I'm not sure (and I mean it) if there can be any piece of
> > software which, if designed for e.g. Linux, can be written w/o using any
> > system headers, libraries or whatsoever.
> 	You can do this with only moderate difficulty and moderate
> inefficiency if
> you want to. All you have to do is:
> 	1) Define your own kernel interface that your proprietary
> module will use.
> 	2) Implement this interface in a kernel module that is GPL.
> 	3) Distribute your proprietary module such that it uses
> only your own
> interface.
> 	This way, your module need only use your own headers, which
> you distribute
> under the GPL as well as other licenses.
> 	The inefficiency comes from having to convert between your
> own structures
> and values to and from the Linux kernel structures and values. If you're
> really clever, you can rig it so that the conversion reduces to
> no-ops on at
> least some kernel versions for many conversions, still without using the
> Linux kernel header files.
> 	You are also free to use subterfuge of any kind to get around any
> restrictions the Linux kernel may attempt to impose upon you because these
> are not license enforcement mechanisms. The Linux kernel does
> not, and *may*
> not, contain any license enforcement mechanisms that affect *use*, and
> obviously anything that could affect the runnning of your module would be
> affecting use. (The GPL does not restrict use and prohibits any
> 'additional
> restrictions', thus any thing that seemed to be an additional restriction
> could not be a license enforment mechanism because the
> restriction is not in
> the license.)
> 	DS

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