1 .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
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23 .TH GETPAGESIZE 2 2010-11-16 "Linux" "Linux Programmer's Manual"
25 getpagesize \- get memory page size
27 .B #include <unistd.h>
29 .B int getpagesize(void);
32 Feature Test Macro Requirements for glibc (see
33 .BR feature_test_macros (7)):
44 !(_POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600)
48 _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
49 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
56 returns the number of bytes in a memory page,
57 where "page" is a fixed-length block,
58 the unit for memory allocation and file mapping performed by
61 .\" This call first appeared in 4.2BSD.
66 call is labeled LEGACY, and in POSIX.1-2001
68 HP-UX does not have this call.
70 Portable applications should employ
71 .I sysconf(_SC_PAGESIZE)
78 long sz = sysconf(_SC_PAGESIZE);
82 (Most systems allow the synonym
89 is present as a Linux system call depends on the architecture.
90 If it is, it returns the kernel symbol
92 whose value depends on the architecture and machine model.
93 Generally, one uses binaries that are dependent on the architecture but not
94 on the machine model, in order to have a single binary
95 distribution per architecture.
96 This means that a user program
99 at compile time from a header file,
100 but use an actual system call, at least for those architectures
101 (like sun4) where this dependency exists.
102 Here libc4, libc5, glibc 2.0 fail because their
104 returns a statically derived value, and does not use a system call.
105 Things are OK in glibc 2.1.