[Qt-interest] LGPL and static linking

[Thiago Macieira]

Em Quinta-feira 26 Novembro 2009, às 01:09:08, Neville Dastur escreveu:
> I wish a Nokia representative would state their position.
> 
Ask and you shall be heard.

Cristina Hamley, legal counsel for Qt Development Frameworks, asked me to post 
the following:

-----------------------------------------

In response to the recent postings regarding static linking under the LGPL, I 
would like to take the opportunity to clarify a few points:

There is debate in the legal and open source communities as to whether static 
linking is permissible under the LGPL version 2.1.  This uncertainty is caused 
by an inconsistency in the LGPL license itself.  The LGPL v. 2.1 defines "a 
work based on the Library" to be anything that would be a derivative work 
under copyright law.  Unfortunately,  the LGPL is neutral from a legal 
jurisdictional point of view and this leaves the question of which 
jurisdiction's copyright laws should be considered undefined and open to 
interpretation (and potentially differing results) depending on numerous 
factors such as where the application is distributed, where it was created, 
etc.  In many jurisdictions, an application that is statically linked with the 
LGPL licensed library will be considered a derivative work.  Thus, in 
accordance with the LGPL's definition of a "work based on the Library", a 
statically linked application could be subject to the provisions regarding 
modification and distribution of the Library included in Sections 1, 2, and 4 
of the LGPL.  Those who believe that static linking is permissible under the 
LGPL v. 2.1 primarily refer to Sections 5 and 6(a) of the LGPL to support 
their argument.  Those arguing that static linking is permitted under the LGPL 
argue that Section 5 specifically acknowledges that the executable that results 
from the static linking of the application with the library is a derivative 
work of the Library.  However, the language in Section 5 gives some 
indications that despite the executable being a derivative work, it can be 
distributed in accordance with Section 6.  Unfortunately,  it is precisely 
this acknowledgment that the executable may be a derivative work that creates 
the inconsistency within the license.

Due to the varying opinions on whether static linking is permissible, it is 
Nokia's recommendation that Qt users dynamically link their applications to 
the LGPL-licensed Qt libraries so as to ensure that the application source 
code, which a user may want to keep private, does not have to be shared with 
downstream recipients.  Ultimately, however, this decision is one of risk and 
the individual Qt user should make this decision based on the specific 
circumstances relevant to his or her particular application.  Some of the 
recent posts have stated a desire to have Nokia's position on whether static 
linking is permissible.  Because the LGPL v. 2.1 source code obligations can 
be enforced by any recipient of the application and LGPL-licensed library, 
Nokia's position on this issue is not particularly relevant and is merely one 
opinion among many.

Moreover, questions have been raised as to why we selected the LGPL v. 2.1 
when we were aware of the debate regarding static linking.  The LGPL v. 2.1 
was selected as we believe that the LGPL v. 2.1 is the open source license 
that best meets our goals of promoting a rich and vibrant Qt developer 
ecosystem in which third parties are able to contribute to the Qt code base 
while also fostering development and distribution of applications by our users 
in the commercial environment.  In making the licensing selection it was 
important to select a license that is well known and widely used/accepted by 
the open source community.  We believe that we were able to accomplish our 
licensing goals without subjecting the open source community to yet another 
new open source license.  Qt's tri-licensing model (commercial, LGPL v. 2.1 
and GPL v. 3.0) permits Qt is be used in virtually all usage scenarios.

Best regards,

Cristy Hamley
Legal Counsel

-----------------------------------------

See also her blog on the subject: http://blog.qt.nokia.com/2009/11/30/qt-
making-the-right-licensing-decision/
-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
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