Problem in MIT-SCREEN-SAVER

Question

I'm using beforelight (v1.3) from XFree86. This program uses MIT-SCREEN-SAVER for screensaver event. It works fine under 5.6, and 5.8 if built with 32-bit. But after I rebuilt it with 64-bit (add -xarch=v9a in Makefile) and ran the binary, I got a core dump in the function XScreenSaverSelectInput(). Workshop reports invalid address alignment in XScreenSaverSelectInput at 0xffffffff7e510108. What could be the problem?

Answer 1

Tested with a simple program, main() does nothing but initializing MIT-SCREEN-SAVER and starting a eventloop listening for screensaverevent. The initialization code is:
int main(argc, argv)
int argc;
char **argv;
Widget toplevel;
XEvent event;
XScreenSaverNotifyEvent *sevent;
XID               kill_id;
Atom          kill_type;
toplevel = XtAppInitialize (&app_con, "Beforelight", NULL, ZERO,
                    &argc, argv, NULL, NULL, ZERO);
display = XtDisplay (toplevel);
root = DefaultRootWindow (display);
screen = DefaultScreen (display);
if (!XScreenSaverQueryExtension (display, &ss_event, &ss_error))
          exit (1);
if (XScreenSaverGetRegistered (display, screen, &kill_id, &kill_type))
          XErrorHandler old_handler = XSetErrorHandler (ignoreError);
          XKillClient (display, kill_id);
          XSync (display, 0);
          XSetErrorHandler (old_handler);
XScreenSaverSelectInput (display, root, ScreenSaverNotifyMask);
XSync (display, False);
XSetScreenSaver(display, MyTimeout, 0, 0, 0);
eventloop();
This works fine when linked with 32-bit, but crashed (sometimes report BadDrawable) in XScreenSaverSelectInput(). I'm wondering if the 64-bit MIT-SCREEN-SAVER doesn't work properly.