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Re: CERN ROOT in debian

Hi Brad,

[Ricardo, I'm CC-ing you on this since I don't know whether you're
subscribed to debian-science.  Hope you aren't getting it twice...]

On 8/10/05, Brad Sawatzky <brad+debian@swatter.net> wrote:
> This is a compilation of what I've picked up through google searches.
> The licensing for ROOT is a bit of a mess (clearly not GPL compatible,
> despite the fact that ROOT links with other explicitly GPL'd software...)
> The problematic clause is the "explicit consent" bit in
>     ...the authors grant permission to modify this software and its
>     documentation for any purpose, provided that such modifications are not
>     distributed without the explicit consent of the authors...
> (from <http://root.cern.ch/root/License.html>).
> Google "debian root license cern" if you want to work through some of the
> relevant threads.  Upstream is aware of the problem but have been unwilling
> to address it.  If anyone is aware of the current state of affairs, please
> post to the list!

Thanks for the concise summary.  We really ought to put this in an FAQ

> (As an aside, I think Kevin did a fantastic job of disentangling the
> astonishingly bad PAW build system, package file-structure, and licensing
> mess into something that conforms to debian Policy.)

If you are ever bored, run "apt-get source cernlib" and poke around in
the debian directory.  Hours of excitement! :-)

> Christian Holm Christensen has been involved in the 'debianizing' of ROOT.
> He has some build instructions up at
>   <http://cholm.home.cern.ch/cholm/root/debs/>
> (FWIW, I haven't been able to get the build process to work under sid yet.
> I suspect the culprit is g++-4.0, but I haven't had time to work on it
> yet.)

Now to the real point of my email--I have a bit more information to
add about ROOT Debianization efforts.  Ricardo Yanez is working on
.debs that will be Policy-compliant and suitable to upload into Debian
as soon as the licensing situation is fixed.  I think the preliminary
.debs are publicly available but I don't recall the URL offhand. 
(Ricardo?)  Other than licensing, the biggest difficulty is that the
ROOT libraries are both shared libs and also modules dynamically
loaded by the main executable at runtime.  Unfortunately the main
executable expects them to be named "libfoo.so" with no soversion, so
(contrary to Policy) it currently isn't possible to have the libfoo.so
symlinks only in the development packages.  Figuring out how to hack
the code to dlopen "libfoo.so.4.04" instead seems non-trivial.

If it turns out that the license doesn't get fixed in the near future,
there is one possibility that would allow us to put a bowdlerized
version of ROOT in non-free.  There exists a C++ version of Minuit
that is licensed under LGPL.  If ROOT was hacked to link against this
library instead of using its own TMinuit class (derived from Cernlib
FORTRAN code), it would no longer be in violation of the GPL with
respect to Cernlib.  (However, the g2root and h2root
Cernlib-compatibility utilities would have to go, as well as a lot of
add-on modules that link against other GPL'ed software.)

We would also need to get permission from the XClass project for ROOT
to use their (LGPL) GUI library code.  (Note that ROOT uses a derived
version of the code, instead of just linking against it!)  Since
XClass mentions ROOT, apparently with approval, on their own project
page, getting a formal permission might not be too hard.

Of course, putting such a hacked version of ROOT in Debian non-free
would be dependent on the permission of ROOT's upstream to allow its
distribution, which might not be forthcoming.

> I did find some pre-built ROOT debs at
>   <http://www.physi.uni-heidelberg.de/~gbrandt/root/non-free/>
> They installed smoothly and a few simple tests work.
> Christian also points to the PaiPix distribution as a source of ROOT debs.
>   <http://aamorimsrv.fis.fc.ul.pt/>
> I poked around but didn't see any simple way of obtaining specific packages
> (just links to the PaiPix live DVD iso).

I do hope that once ROOT finally can be part of Debian, we don't have
to support upgrades from too many different unofficial .deb packages
-- could be quite challenging.  These forks could have been avoided if
ROOT had been re-licensed two years ago :-(


Kevin B. McCarty <kmccarty@princeton.edu>   Physics Department
WWW: http://www.princeton.edu/~kmccarty/    Princeton University
GPG: public key ID 4F83C751                 Princeton, NJ 08544

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