Hallo,
I have a question concerning standalone programs based on u-boot and GPL, since I'm not really sure whether the way how the u-boot source files are set up allows GPL free standalone programs.
u-boot allows the use of standalone applications which can be loaded and executed by u-boot. These applications can use certain u-boot functions. There are several advantages of this approach. It also allows to build applications, which don't need to be released under GPL. In general, this looks good. And for certain tasks this is exactly what we need.
However, when looking at the GPL details, I'm not sure whether this really works with the current u-boot sources (from a legal point of view):
(a) the source code of the hello_world example for a standalone application has a GPL header. If you are legally strict, this can mean every standalone application is a derived work from this example and therefore restricted to GPL.
(b) When you want to write a standalone application you need - as a minimum - to include "exports.h" (for the interface definitions), which requires "common.h" as additional header file. Both files are not included in the COPYING information which allows the use outside of GPL. The header file "common.h" (and other header files, which are included within common.h) even have a GPL header.
(c) you need to link your standalone application against stub.o (or the corresponding library). I did not find any statement (e.g., within stub.c), that this part is GPL-free (e.g., similar to LGPL).
So, from my point of view (although I'm not a lawyer), there are some doubts about a GPL free standalone application based on the actual u-boot sources. I believe there should be some enhancements to clarify this subject:
(1) GPL free standalone examples (2) a really GPL free exports.h (similar to include/image.h) (3) some explanations that the use of the source file "examples/standalone/stub.c" is not GPL restricted.
I know that this is a very strict view to this subject (but that is the way legal people look at it). I'm interested in a feedback from others who already were involved with this issue.
With best regards, Manfred Neugebauer
Siemens AG Industry Sector Industry Automation Division Advanced Technologies & Standards mailto:manfred.neugebauer@siemens.com
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