Re: Sparc/Linux

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From: Daniel Veillard (Daniel.Veillard@w3.org)
Date: Wed Sep 30 1998 - 19:24:16 EDT

> Oh great - so the longjmp on the Sparc/Linux unrolls the stack when you
> do a longjmp to the indicated point in the jmpbuf ... which is just fine
> if your using setjmp/longjmp for their usual purpose, but no so good if
> you use it to create threads. I'm looking for a work around ... but it
> anyone knows one please let me know.

  What I used to do is the following at thread creation time:
 create() {
     malloc stack
     setjmp in the father
     the if (setjmp (...)) { launch child process ()
                              Using global variables only
                              suicide()
                            }
     else {
         modify the SP using the apriori knowledge of the SP index
         in the jmpbuf (father)
     }
 }

 Under that scheme, the fact that the longjmp unroll the stack is harmless,
(I remember however that AIX was checking for the SP and exit()ing if not
 "within range" :-(, I had to rewrite them).

 That's lead to the second possiblility: take setjmp/longjmp from S/Linux
 libc and modify it, *grin* ...

Daniel 

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