mctl(3)                 (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.



   8/91                                                                 Page 1

   mctl(3)                 (BSD Compatibility Package)                 mctl(3)


         MCUNLOCKAS
               Remove address space memory lock, and locks on all current
               mappings.  This function is used to support munlockall(3).
               addr 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                                                                 8/91