PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       sys/mman.h — memory management declarations

SYNOPSIS

       #include <sys/mman.h>

DESCRIPTION

       The <sys/mman.h> header shall define the following symbolic constants for use as protection options:

       PROT_EXEC     Page can be executed.

       PROT_NONE     Page cannot be accessed.

       PROT_READ     Page can be read.

       PROT_WRITE    Page can be written.

       The <sys/mman.h> header shall define the following symbolic constants for use as flag options:

       MAP_FIXED     Interpret addr exactly.

       MAP_PRIVATE   Changes are private.

       MAP_SHARED    Share changes.

       The <sys/mman.h> header shall define the following symbolic constants for the msync() function:

       MS_ASYNC      Perform asynchronous writes.

       MS_INVALIDATE Invalidate mappings.

       MS_SYNC       Perform synchronous writes.

       The <sys/mman.h> header shall define the following symbolic constants for the mlockall() function:

       MCL_CURRENT   Lock currently mapped pages.

       MCL_FUTURE    Lock pages that become mapped.

       The  <sys/mman.h>  header  shall define the symbolic constant MAP_FAILED which shall have type void * and
       shall be used to indicate a failure from the mmap() function .

       If the Advisory Information option is supported, the <sys/mman.h> header shall define symbolic  constants
       for the advice argument to the posix_madvise() function as follows:

       POSIX_MADV_DONTNEED
             The application expects that it will not access the specified range in the near future.

       POSIX_MADV_NORMAL
             The  application  has  no advice to give on its behavior with respect to the specified range. It is
             the default characteristic if no advice is given for a range of memory.

       POSIX_MADV_RANDOM
             The application expects to access the specified range in a random order.

       POSIX_MADV_SEQUENTIAL
             The application expects to access the specified range sequentially from lower addresses  to  higher
             addresses.

       POSIX_MADV_WILLNEED
             The application expects to access the specified range in the near future.

       The  <sys/mman.h>  header  shall  define  the  following  symbolic  constants  for  use  as flags for the
       posix_typed_mem_open() function:

       POSIX_TYPED_MEM_ALLOCATE
             Allocate on mmap().

       POSIX_TYPED_MEM_ALLOCATE_CONTIG
             Allocate contiguously on mmap().

       POSIX_TYPED_MEM_MAP_ALLOCATABLE
             Map on mmap(), without affecting allocatability.

       The <sys/mman.h> header shall define the mode_t, off_t, and size_t types as described in <sys_types.h>.

       The <sys/mman.h> header shall define the posix_typed_mem_info structure, which shall include at least the
       following member:

           size_t  posix_tmi_length  Maximum length which may be allocated
                                     from a typed memory object.

       The following shall be declared as functions and may also be defined as macros. Function prototypes shall
       be provided.

           int    mlock(const void *, size_t);
           int    mlockall(int);
           void  *mmap(void *, size_t, int, int, int, off_t);
           int    mprotect(void *, size_t, int);
           int    msync(void *, size_t, int);
           int    munlock(const void *, size_t);
           int    munlockall(void);
           int    munmap(void *, size_t);
           int    posix_madvise(void *, size_t, int);
           int    posix_mem_offset(const void *restrict, size_t, off_t *restrict,
                      size_t *restrict, int *restrict);
           int    posix_typed_mem_get_info(int, struct posix_typed_mem_info *);
           int    posix_typed_mem_open(const char *, int, int);
           int    shm_open(const char *, int, mode_t);
           int    shm_unlink(const char *);

       The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       <sys_types.h>

       The System Interfaces volume of POSIX.1‐2017, mlock(), mlockall(), mmap(), mprotect(), msync(), munmap(),
       posix_madvise(),   posix_mem_offset(),  posix_typed_mem_get_info(),  posix_typed_mem_open(),  shm_open(),
       shm_unlink()

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee  document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .