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:

• ^[MF] The Memory Mapped Files option

• ^[SHM] The Shared Memory Objects option

• ^[ML] The Process Memory Locking option

• ^[MPR] The Memory Protection option

• ^[TYM] The Typed Memory Objects option

• ^[SIO] The Synchronized Input and Output option

• ^[ADV] The Advisory Information option

^[MC2] 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

^[MC2] Page can be read.

PROT_WRITE

^[MC2] Page can be written.

PROT_EXEC

^[MC2] Page can be executed.

PROT_NONE

^[MC2] Page cannot be accessed.

The following flag options shall be defined:

MAP_SHARED

^[MF|SHM] Share changes.

MAP_PRIVATE

^[MF|SHM] Changes are private.

MAP_FIXED

^[MF|SHM] Interpret addr exactly.

The following flags shall be defined for msync():

MS_ASYNC

^[MF|SIO] Perform asynchronous writes.

MS_SYNC

^[MF|SIO] Perform synchronous writes.

MS_INVALIDATE

^[MF|SIO] Invalidate mappings.

^[ML] The following symbolic constants shall be defined for the mlockall() function:

MCL_CURRENT

^[ML] Lock currently mapped pages.

MCL_FUTURE

^[ML] Lock pages that become mapped.

^[MF|SHM] The symbolic constant MAP_FAILED shall be defined to indicate a failure from the mmap() function.

^[MC1] 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.

^[TYM] 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>.

^[TYM] 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.

[MLR]
int    mlock(const void *, size_t);

[ML]
int    mlockall(int);

[MC3]
void  *mmap(void *, size_t, int, int, int, off_t);

[MPR]
int    mprotect(void *, size_t, int);

[MF|SIO]
int    msync(void *, size_t, int);

[MLR]
int    munlock(const void *, size_t);

[ML]
int    munlockall(void);

[MC3]
int    munmap(void *, size_t);

[ADV]
int    posix_madvise(void *, size_t, int);

[TYM]
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);

[SHM]
int    shm_open(const char *, int, mode_t);
int    shm_unlink(const char *);

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

<sys/types.h>, the System Interfaces volume of IEEE Std 1003.1-2001, mlock(), mlockall(), mmap(), mprotect(), msync(), munlock(), munlockall(), munmap(), posix_mem_offset(), posix_typed_mem_get_info(), posix_typed_mem_open(), shm_open(), shm_unlink()

CHANGE HISTORY

First released in Issue 4, Version 2.

Issue 5

Updated for alignment with the POSIX Realtime Extension.

Issue 6

The <sys/mman.h> header is marked as dependent on support for either the Memory Mapped Files, Process Memory Locking, or Shared Memory Objects options.

The following changes are made for alignment with IEEE Std 1003.1j-2000:

• The TYM margin code is added to the list of margin codes for the <sys/mman.h> header line, as well as for other lines.

• The POSIX_TYPED_MEM_ALLOCATE, POSIX_TYPED_MEM_ALLOCATE_CONTIG, and POSIX_TYPED_MEM_MAP_ALLOCATABLE flags are added.

• The posix_tmi_length structure is added.

• The posix_mem_offset(), posix_typed_mem_get_info(), and posix_typed_mem_open() functions are added.

The restrict keyword is added to the prototype for posix_mem_offset().

IEEE PASC Interpretation 1003.1 #102 is applied, adding the prototype for posix_madvise().

IEEE Std 1003.1-2001/Cor 1-2002, item XBD/TC1/D6/16 is applied, correcting margin code and shading errors for the mlock() and munlock() functions.

IEEE Std 1003.1-2001/Cor 1-2002, item XSH/TC1/D6/34 is applied, changing the margin code for the mmap() function from MF|SHM to MC3 (notation for MF|SHM|TYM).

IEEE Std 1003.1-2001/Cor 1-2002, item XSH/TC1/D6/36 is applied, changing the margin code for the munmap() function from MF|SHM to MC3 (notation for MF|SHM|TYM).