Recently came across some code that runs ok on 6.3.2 and crashes on 6.5.0.

Long story short, it appears that when we have a nested C function that generates a "trampoline" call, this is not 
working on 6.5.0.

I noticed the "-mx" option on procnto, which is supposed to be the default.  So I tried specifying the option and it 
didn't change.

I also found that on some x86 machines, e.g., old Pentium IV, and VMware ESXi, the problem does not occur.  But it 
occurs on Pentium D, Core2, and later.

I mainly wanted to confirm whether it's possible that procnto is not enabling PROT_EXEC for stack meomry, even if -mx is
 specified?  Or maybe I don't understand the problem.

Here is a sample program that crashes reliably on 6.5.0:

#include <stdio.h>
#include <stdlib.h>
int main ()
{
   int callbacks = 0;
   static char buf [] = "9876543210";
   int cmp (const void *p1, const void *p2)
   {
      callbacks++;
      return *(char *)p1 - *(char *)p2;
      }
   qsort(buf, sizeof buf - 1, sizeof buf[0], cmp);
   return 0;
   }