Subject: [clisp-list] about libsigsegv

From: "Hoehle, Joerg-Cyril" <[email-masked]>
Date: Tue Feb 25 01:47:06 2003

Hi,

what is the use of libsigsegv? My naive understanding is that being able to catch and react on SIGSEGV etc. is an essential part of a generational garbage collection.

However, the sigsegv library was removed from the CLISP sources between 2.28 and 2.30. I nevertheless built CLISP-2.30 using the 2.28 libsigsegv.

What is sigsegv used for? What happens when it's not there?

Thanks for shedding any light on this issue.

unix/INSTALL says
  - GNU libsigsegv (highly recommended for C stack overflow detection),
I'm not in favour of removing a "highly recommended" library from the source tree, especially considering its small size.

BTW, here's a tiny copy&paste error within configure
checking for libsigsegv... yes                                     
checking how to link with libiconv... /home/hoehle/lib/libsigsegv.a
                             ^^^^^ sigsegv

Regards,
	Jörg Höhle.

FWIW, sigsegv/README says:
This is a library for handling page faults in user mode. A page fault  
occurs when a program tries to access to a region of memory that is    
currently not available. Catching and handling a page fault is a useful
technique for implementing:                                            
                                                                       
  - pageable virtual memory,                                           
  - memory-mapped access to persistent databases,                      
  - generational garbage collectors,                                   
  - stack overflow handlers,                                           
  - distributed shared memory,

---

From: Sam Steingold <[email-masked]>
Date: Tue Feb 25 07:28:33 2003

> * In message <[email-masked]>
> * On the subject of "[clisp-list] about libsigsegv"
> * Sent on Tue, 25 Feb 2003 10:46:06 +0100
> * Honorable "Hoehle, Joerg-Cyril" <[email-masked]> writes:
>
> What is sigsegv used for?

SP-overflow detection.

> What happens when it's not there?

you get a segfault instead of "Program stack overflow. RESET." on some
platforms.

> I'm not in favour of removing a "highly recommended" library from the
> source tree, especially considering its small size.

we also "highly recommend" readline and libiconv.
we cannot distribute with CLISP all the libraries we want to use.

-- 
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