Re: [Xen-devel] Re: Copyright/licensing info ?

["Karsten M. Self" <kself@xxxxxxxxxxxxx>]

on Wed, Dec 14, 2005 at 02:31:00PM -0500, Sean Dague (sean@xxxxxxxxx) wrote:
> On Wed, Dec 14, 2005 at 07:02:11PM +0000, Keir Fraser wrote:
> > 
> > On 14 Dec 2005, at 18:35, Sean Dague wrote:
> > 
> > >>Those comments were removed because there si a single license for all
> > >>Xen public interface header files in xen/include/public/COPYING.
> > >
> > >In my limitted understanding of US Copyright laws, there needs to be a
> > >license stanza in every file, otherwise default copyright is assumed.  
> > >At
> > >least as a safety measure there should probably be a header in each of 
> > >those
> > >files.
> > 
> > I removed a license string, not a copyright string. What would a 
> > 'default license' be? Covering multiple files with a single COPYING 
> > file seems standard practise (e.g., Linux).
> 
> Sorry, default copyright, not default license.  
> 
> First, IANAL, so this might not be 100% correct, however, in my
> understanding of US copyright (which applies to at least some portion of the
> Xen code), it goes something like this.
> 
> In the US everything caries implicit copyright.  To ensure that something
> remains open source software, it needs to carry a license statement in that
> file.  An external file referencing headers saying "Those files are under
> this license" isn't necessarily adequate.

<IANAL>

Your understanding is partially correct.  Without explicit licensing
terms, relevant copyright law holds.  In the US, that's 17 USC,
particularly sections 106 & 106a as limited by 107 - 122.

    http://www.law.cornell.edu/uscode/html/uscode17/usc_sup_01_17_10_1.html

The GPL license terms need not be specifically attached to any
given file.  In the case of most li It's convention (and sometimes
useful) to note the license used in file headers, but not strictly
necessary.  The usual GPL text itself includes guidelines on applying
the GPL to a program ("How to Apply These Terms to Your New Programs"),
which reference, but don't specifically include the full text of the
GPL.  Note that these are _guidelines_ and not _requirements_.



One project with which I'm familar had a discussion of a similar issue,
whether or not a copy of the GPL needed to be present on the system when
it booted.  As a bootable floppy-based distro, space was at a premium,
and as a feature was bidirectional regeneration of the distro -- the
packed form could be unpacked to boot a system, the unpacked form could
be modified and repacked, carrying one (or worse, multiple) copies of
the licensing files was seen as burdensome.  Most of the details are in
private correspondence.

Guidance from the FSF was that a separate license file in the download
archive was sufficient.  This is what you'll find today when you
download Tom's Root Boot:

    http://www.toms.net/rb/
    http://www.toms.net/rb/download.html

Another project, the Debian Project, includes a reference copy of the
GNU GPL in /usr/share/common-licenses/GPL, which was also deemed
sufficient by the FSF:

    http://bugs.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=78341

While some GPL'd Debian packages include the full text of the GPL, the
bulk of them don't.  At 18K per toss, and roughly 85% of Debian's nearly
19,000 software packages under the GPL, that's 276 MB of space savings,
per arch, per release, on Debian mirrors and installs.

 
> In the "better safe than sorry" realm, it would be good to have a BSD
> license stanza in each of the header files, if that is the final
> license they will be under.

Useful, but to my understanding not strictly necessary so long as
licensing text clearly defining what is covered is included in
distributions of the work.

</IANAL>


Cheers.

-- 
Karsten M. Self <karsten@xxxxxxxxxxxxx>
XenSource, Inc.
2300 Geng Road #250                                +1 650.798.5900 x259
Palo Alto, CA 94303                                +1 650.493.1579 fax

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