Each architecture needs a crt0.S file.  The crt0.S assembly routine
typically corresponds to the following pseudo-C code.  In addition,
each architecture needs any support routines that gcc-generated code
expects to find in the system library -- Alpha, for example, needs
divide subroutines.


extern char **environ;
extern int main(int, char **, char **);
extern __noreturn exit(int);

__noreturn _start(void)
{
  intptr_t *argptr = __stack_pointer(); /* Usually -- e.g. SPARC is special */
  int argc;
  char **argv, **envp;

#if STACK_GROWS_UP
  argc = (int)*argptr--;
  argv = (char **)argptr;
  envp = argv-(argc+1);
#else
  argc = (int)*argptr++;
  argv = (char **)argptr;
  envp = argv+(argc+1);
#endif

  environ = envp;

  exit(main(argc, argv, envp));
}