mman (0p) - Linux Manuals

mman: memory management declarations

NAME

sys/mman.h - memory management declarations

SYNOPSIS

#include <sys/mman.h>

DESCRIPTION

The <sys/mman.h> header shall be supported if the implementation supports at least one of the following options:

*

The Memory Mapped Files option

*

The Shared Memory Objects option

*

The Process Memory Locking option

*

The Memory Protection option

*

The Typed Memory Objects option

*

The Synchronized Input and Output option

*

The Advisory Information option

*

The Typed Memory Objects option

If one or more of the Advisory Information, Memory Mapped Files, or Shared Memory Objects options are supported, the following protection options shall be defined:

PROT_READ

Page can be read.

PROT_WRITE

Page can be written.

PROT_EXEC

Page can be executed.

PROT_NONE

Page cannot be accessed.

The following flag options shall be defined:

MAP_SHARED

Share changes.

MAP_PRIVATE

Changes are private.

MAP_FIXED

Interpret addr exactly.

The following flags shall be defined for msync():

MS_ASYNC

Perform asynchronous writes.

MS_SYNC

Perform synchronous writes.

MS_INVALIDATE

Invalidate mappings.

The following symbolic constants shall be defined for the mlockall() function:

MCL_CURRENT

Lock currently mapped pages.

MCL_FUTURE

Lock pages that become mapped.

The symbolic constant MAP_FAILED shall be defined to indicate a failure from the mmap() function.

If the Advisory Information and either the Memory Mapped Files or Shared Memory Objects options are supported, values for advice used by posix_madvise() shall be defined as follows:

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_SEQUENTIAL

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

POSIX_MADV_RANDOM

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

POSIX_MADV_WILLNEED

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

POSIX_MADV_DONTNEED

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

The following flags shall be defined for posix_typed_mem_open():

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 mode_t, off_t, and size_t types shall be defined as described in <sys/types.h> .

The <sys/mman.h> header shall define the structure posix_typed_mem_info, which includes 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.

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .