• Straight foward copy is time and space consuming
• Different processes should be able to share the read-only code (not the data) segment.

Rather than copying a program into a process's address space, a better choice is to map the program file into the address space.

       void *mmap(void *start, size_t length, int prot, int flags,
                  int fd, off_t offset);
   

• start - just a suggestion to the operating system. Use 0.
• length - size of the file in bytes! (see stat or fstat functions)
• prot
  • PROT_EXEC Pages may be executed.
  • PROT_READ Pages may be read.
  • PROT_WRITE Pages may be written (and read).
  • PROT_NONE Pages may not be accessed.
• flags
  • MAP_SHARED
  • MAP_PRIVATE