Re: [bug-libsigsegv] libsigsegv under LGPL ?

[Bruno Haible]

Hi Daniel,

When sending questions relating to GNU libsigsegv, please use the mailing
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> I also use hardware stack overflow detection for GNU Prolog (a native
> Prolog compiler I develop and maintain). Since your library does the
> same I'm studying the possibility to use it (porting this is always a
> bit painfull). However since GNU Prolog is released under LGPL (in fact
> a dual license GPL+LGPL), I'd like to know if it is possible for you to
> release your library under LGPL ?

LGPL means that proprietary programs can use the code just by linking to
our library. The libsigsegv is a significant functionality; it can enable
globally visible features like robustness or a decent garbage collector.
Can you mention reasons why it would be good for the GNU project to allow
these features to be used, at zero cost, by proprietary programs?

> Other question: is your library thread-safe ?

The library has global variables and global state. Therefore you need to
ask more specifically: What are the operations that you wish to perform
in different threads, without explicit locking on your side?

> PS: BTW, and for the history, I use hardware stack detection since 1993
> (in wamcc: the predecessor of GNU Prolog system). This is described in:
> 
> P. Codognet and D. Diaz. “wamcc: Compiling Prolog to C”. International
> Conference on Logic Programming (ICLP), p. 317-331, Tokyo, Japan, 1995.
> (Section 5 Memory management)

If you want to add to libsigsegv a piece of documentation that explains
when the technique of page faults was used by whom, and who invented what,
feel free to contribute it. All I know is that I worked on this for clisp
around 1993, and that at this time already is was a well-known idea.
Or you can enhance Wikipedia's article 
<http://en.wikipedia.org/wiki/Page_fault>.

Bruno