mctl(3)            UNIX System V(BSD Compatibility Package)             mctl(3)


NAME
      mctl - memory management control

SYNOPSIS
      cc [ flag. . . ] file . . .  -lucb

      #include <sys/types.h>
      #include <sys/mman.h>
      mctl(caddrt addr, sizet len, int function, void *arg);

DESCRIPTION
      mctl applies a variety of control functions over pages identified by the
      mappings established for the address range [addr, addr + len).  The
      function to be performed is identified by the argument function.  Valid
      functions are defined in mman.h as follows.

      MCLOCK
            Lock the pages in the range in memory.  This function is used to
            support mlock.  See mlock(3) for semantics and usage.  arg is
            ignored.

      MCLOCKAS
            Lock the pages in the address space in memory.  This function is
            used to support mlockall.  See mlockall(3) for semantics and usage.
            addr and len are ignored.  arg is an integer built from the flags:
                            MCLCURRENT   Lock current mappings
                            MCLFUTURE    Lock future mappings

      MCSYNC
            Synchronize the pages in the range with their backing storage.
            Optionally invalidate cache copies.  This function is used to
            support msync.  See msync(3) for semantics and usage.  arg is used
            to represent the flags argument to msync.  It is constructed from
            an OR of the following values:
                            MSSYNC         Synchronized write
                            MSASYNC        Return immediately
                            MSINVALIDATE   Invalidate mappings

            MSASYNC returns after all I/O operations are scheduled.  MSSYNC
            does not return until all I/O operations are complete.  Specify
            exactly one of MSASYNC or MSSYNC.  MSINVALIDATE invalidates all
            cached copies of data from memory, requiring them to be re-obtained
            from the object's permanent storage location upon the next
            reference.

      MCUNLOCK
            Unlock the pages in the range.  This function is used to support
            munlock.  See munlock(3) for semantics and usage.  arg is ignored.

      MCUNLOCKAS
            Remove address space memory lock, and locks on all current
            mappings.  This function is used to support munlockall(3).  addr


10/89                                                                    Page 1

mctl(3)            UNIX System V(BSD Compatibility Package)             mctl(3)


            and len must have the value 0.  arg is ignored.

RETURN VALUE
      mctl returns 0 on success, -1 on failure.

ERRORS
      mctl fails if:

      EAGAIN              Some or all of the memory identified by the operation
                          could not be locked due to insufficient system
                          resources.

      EBUSY               MSINVALIDATE was specified and one or more of the
                          pages is locked in memory.

      EINVAL              addr is not a multiple of the page size as returned
                          by getpagesize.

      EINVAL              addr and/or len do not have the value 0 when
                          MCLOCKAS or MCUNLOCKAS are specified.

      EINVAL              arg is not valid for the function specified.

      EIO                 An I/O error occurred while reading from or writing
                          to the file system.

      ENOMEM              Addresses in the range [addr, addr + len) are invalid
                          for the address space of a process, or specify one or
                          more pages which are not mapped.

      EPERM               The process's effective user ID is not super-user and
                          one of MCLOCK, MCLOCKAS, MCUNLOCK, or MCUNLOCKAS
                          was specified.

SEE ALSO
      getpagesize(3)

      mmap(2), mlock(3C), mlockall(3C), msync(3C) in the Programmer's Reference
      Manual















Page 2                                                                    10/89