Date: Fri, 24 Sep 1999 16:18:15 -0400 (EDT) From: Zhihui Zhang <zzhang@cs.binghamton.edu> To: Alfred Perlstein <bright@wintelcom.net> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: A program that causes "bus error" Message-ID: <Pine.GSO.3.96.990924161314.23327B-100000@sol.cs.binghamton.edu> In-Reply-To: <Pine.BSF.4.05.9909241303460.6368-100000@fw.wintelcom.net>
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On Fri, 24 Sep 1999, Alfred Perlstein wrote:
>
> On Fri, 24 Sep 1999, Zhihui Zhang wrote:
>
> >
> > The following program causes "bus error" on a Sun workstation whether I
> > compile it with cc or gcc:
> >
> > #include <stdio.h>
> > main()
> > {
> > union {
> > char a[10]; int i;
> > } u;
> > int * p = (int *) &(u.a[1]);
> > * p = 17;
> > printf("%d\n", *p);
> > }
>
> You are violating sparc's alignment restrictions by doing this,
> a x86 machine will deal with the alignment issues in hardware however
> a sparc will trap to the OS (SIGBUS) if non-aligned accesses are
> attempted.
>
Thanks. This code is taken from the book "Expert C Programming - Deep C
Secrets". It is a good book. The auther must be very familiar with SunOS.
-Zhihui
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