[Gcl-devel] Re: Can't build ACL2 using GCL under Mac OS X 3.3

[Camm Maguire]

Greetings!

Aurelien Chanudet <address@hidden> writes:

> Hi Camm & all,
> 
> On May 22, 2004, at 4:54, Camm Maguire wrote:
> 
> > Greetings!
> >
> > I'm forwarding this to the GCL devel list and our MacOS X maintainer
> > for more detailed commentary.
> 
> Thanks for that.
> 

And thank you very much for your help!

... 

> > John Matthews <address@hidden> writes:
> >
> However, I remember encountering this kind of SGC related issue you
> seem to be running on. In my experience, compilation occasionally
> happened to hang at this stage for me in the past because of the way
> segmentation faults are handled on OS X. First of all, the signal
> raised by segmentation faults on OS X appears to be different from the
> one raised on Linux. Second of all, si_addr does not contain the
> faulting address on OS X, which is a bug in Darwin. To workaround
> this,  you have to look at the dar field of the exception state. I'm
> forwarding a copy of a mail I sent to one of Apple's development
> mailing lists in the hope that will help you understand what I'm
> alluding to here.
> 

 I would have thought a bad fault address would result in a crash, not
 an infinite loop.  It would be interesting to notice if you can
 trigger the 'fault address recovery failure' message for such
 situations when doing simply (si::sgc-on t) in GCL when your 'dar
 exception state' workaround is disabled.

Take care,


> Could you please compile and run the following code ? Your output
> should look like : "addr = 0x00000043".
> 
> #include <signal.h>
> #include <unistd.h>
> #include <stdio.h>
> #include <sys/ucontext.h>
> 
> void handler (int sig, siginfo_t *info, void *scp)
> {
>       ucontext_t *uc = (ucontext_t *)scp;
>       fprintf(stderr, "addr = 0x%08lx\n", uc->uc_mcontext->es.dar);
>       _exit(99);
> }
> 
> int main(void)
> {
>       struct sigaction sact;
>       int ret;
> 
>       sigfillset(&(sact.sa_mask));
>       sact.sa_flags = SA_SIGINFO;
>       sact.sa_sigaction = (void (*)())handler;
>       ret = sigaction (SIGBUS, &sact, 0);
>       return *(int *)0x43;
> }
> 
> Please, keep us posted !
> 
> Aurelien
> 
> 
> 
> 

-- 
Camm Maguire                                            address@hidden
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