title: How do I choose a fixed address for mmap?
body: <p><code>mmap()</code> can be optionally supplied with a fixed location to place the map.  I would like to mmap a file and then have it available to a few different programs at the same virtual address in each program.  I don't care what the address is, just as long as they all use the same address.  If need be, the address can be chosen by one of them at run time (and communicated with the others via some other means).</p>
  
  <p>Is there an area of memory that Linux guarantees to be unused (by the application and by the kernel) that I can map to?  How can I find one address that is available in several running applications?</p>