20001229-1.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

/* This testcase originally provoked an unaligned access fault on Alpha.

   Since Digital Unix and Linux (and probably others) by default fix
   these up in the kernel, the failure was not visible unless one 
   is sitting at the console examining logs.

   So: If we know how, ask the kernel to deliver SIGBUS instead so
   that the test case visibly fails.  */
   
#if defined(__alpha__) && (defined(__linux__) || defined(__osf__))
#ifdef __linux__
#include <asm/sysinfo.h>
#include <asm/unistd.h>

static inline int
setsysinfo(unsigned long op, void *buffer, unsigned long size,
           int *start, void *arg, unsigned long flag)
{
  syscall(__NR_osf_setsysinfo, op, buffer, size, start, arg, flag);
}

#else
#include <sys/sysinfo.h>
#include <sys/proc.h>
#endif
   
static void __attribute__((constructor))
trap_unaligned(void)
{
  unsigned int buf[2];
  buf[0] = SSIN_UACPROC;
  buf[1] = UAC_SIGBUS | UAC_NOPRINT;
  setsysinfo(SSI_NVPAIRS, buf, 1, 0, 0, 0);
}
#endif /* alpha */

void foo(char *a, char *b) { }

void showinfo()
{
    char uname[33] = "", tty[38] = "/dev/";
    foo(uname, tty);
}

int main()
{
  showinfo ();
  exit (0);
}