Fwd: [PETSC #18705] PETSc and Cygwin License (POSIX layer)

Matthew Knepley petsc-maint at mcs.anl.gov
Thu Dec 4 12:04:00 CST 2008

I for one think it should be possible to remove 'make' from the
toolchain, leaving us with only win32fe, which we distribute. Thus
I think we could abandon cygwin once and for all. I would even be
willing to write a \emph{make clone} to accomplish this, even though
I am a committed enemy of make (which once TP'ed my house).


---------- Forwarded message ----------
From: Barry Smith <bsmith at mcs.anl.gov>
Date: Thu, Dec 4, 2008 at 12:00 PM
Subject: Re: [PETSC #18705] PETSc and Cygwin License (POSIX layer)
To: Stefan Benkler <benkler at itis.ethz.ch>
Cc: petsc-maint at mcs.anl.gov


   Here is my understanding of the situation.

   Conjecture: You CAN use an open source compiler (GNU)  to compile
proprietary code and then sell
the binaries without making the proprietary code GNU licensed so long as you
just use the
GNU compilers out of the box and don't change their source code and don't
include the compliers
libraries in your binaries.

  IF this is true then you are safe, the Cygwin environment is only used by
PETSc to have
a system to compile PETSc. None of it is included in the binaries generated.

 On the other hand, if my initial conjecture is wrong, then there could be a


We've tried over the years to use Windows "posix" environments to develop a
build system
for PETSc so we don't need cygwin to build PETSc. Unfortunately their stuff
is so "un-unix"
like that it just wasn't practical and using developers studio to build
PETSc directly is
possible but requires some how getting all the PETSc source properly into
developers studio
and as far as I know the only way to do this is manually through the gui
which is very painful;
plus if we change something in the Unix build side later we'd need to change
it manually
on the developers studio side.

If the situation has changed and Windows does provide a reasonable way to
build large
unix codes I'd love to hear about it and use it. We hate cygwin but feel
with have no other
reasonable option.

On Dec 4, 2008, at 3:33 AM, Stefan Benkler wrote:

 Dear PETSc developers
> Since a while, I successfully use your fantastic library on Windows. Thank
> you very much!
> Lately, I had a discussion about the involved copyrights/licenses with a
> colleague. The main point was if PETSc requires the POSIX layer of cygwin on
> Windows (and therefore would need to fulfill cygwin's GPL license).
> My standpoint was that cygwin is just used to configure and build the
> library, but only native Windows libraries (using MS or Intel's Windows
> compiler, MKL) are finally linked to the PETSc libs. However, I have
> difficulties to proof this claim, which is the reason for this email.
> Please comment/clarify the licensing on a Windows system.
> Thanks a lot for your informations.
> Best regards
>  Stefan Benkler

What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
-- Norbert Wiener
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