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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>munmap</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="munmap"></a> <a name="tag_03_400"></a><!-- munmap --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_400_01"></a>NAME</h4><blockquote>munmap - unmap pages of memory</blockquote><h4><a name="tag_03_400_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('MC3')">MC3</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/sys/mman.h.html">sys/mman.h</a>><br><br> int munmap(void *</tt><i>addr</i><tt>, size_t</tt> <i>len</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_400_03"></a>DESCRIPTION</h4><blockquote><p>The <i>munmap</i>() function shall remove any mappings for those entire pages containing any part of the address space of theprocess starting at <i>addr</i> and continuing for <i>len</i> bytes. Further references to these pages shall result in thegeneration of a SIGSEGV signal to the process. If there are no mappings in the specified address range, then <i>munmap</i>() has noeffect.</p><p>The implementation shall require that <i>addr</i> be a multiple of the page size {PAGESIZE}.</p><p>If a mapping to be removed was private, any modifications made in this address range shall be discarded.</p><p><sup>[<a href="javascript:open_code('ML')">ML|MLR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">Any memory locks (see <a href="mlock.html"><i>mlock</i>()</a> and <a href="mlockall.html"><i>mlockall</i>()</a> ) associated withthis address range shall be removed, as if by an appropriate call to <a href="../functions/munlock.html"><i>munlock</i>()</a>. <imgsrc="../images/opt-end.gif" alt="[Option End]" border="0"></p><p><sup>[<a href="javascript:open_code('TYM')">TYM</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">If a mapping removed from a typed memory object causes the corresponding address range of the memory pool to be inaccessible by anyprocess in the system except through allocatable mappings (that is, mappings of typed memory objects opened with thePOSIX_TYPED_MEM_MAP_ALLOCATABLE flag), then that range of the memory pool shall become deallocated and may become available tosatisfy future typed memory allocation requests.</p><p>A mapping removed from a typed memory object opened with the POSIX_TYPED_MEM_MAP_ALLOCATABLE flag shall not affect in any waythe availability of that typed memory for allocation. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p><p>The behavior of this function is unspecified if the mapping was not established by a call to <a href="../functions/mmap.html"><i>mmap</i>()</a>.</p></blockquote><h4><a name="tag_03_400_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, <i>munmap</i>() shall return 0; otherwise, it shall return -1 and set <i>errno</i> to indicate theerror.</p></blockquote><h4><a name="tag_03_400_05"></a>ERRORS</h4><blockquote><p>The <i>munmap</i>() function shall fail if:</p><dl compact><dt>[EINVAL]</dt><dd>Addresses in the range [<i>addr</i>,<i>addr</i>+<i>len</i>) are outside the valid range for the address space of aprocess.</dd><dt>[EINVAL]</dt><dd>The <i>len</i> argument is 0.</dd><dt>[EINVAL]</dt><dd>The <i>addr</i> argument is not a multiple of the page size as returned by <a href="../functions/sysconf.html"><i>sysconf</i>()</a>.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_400_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_400_07"></a>APPLICATION USAGE</h4><blockquote><p>The <i>munmap</i>() function is only supported if the Memory Mapped Files option or the Shared Memory Objects option issupported.</p></blockquote><h4><a name="tag_03_400_08"></a>RATIONALE</h4><blockquote><p>The <i>munmap</i>() function corresponds to SVR4, just as the <a href="../functions/mmap.html"><i>mmap</i>()</a> functiondoes.</p><p>It is possible that an application has applied process memory locking to a region that contains shared memory. If this hasoccurred, the <i>munmap</i>() call ignores those locks and, if necessary, causes those locks to be removed.</p></blockquote><h4><a name="tag_03_400_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_400_10"></a>SEE ALSO</h4><blockquote><p><a href="mlock.html"><i>mlock</i>()</a> , <a href="mlockall.html"><i>mlockall</i>()</a> , <a href="mmap.html"><i>mmap</i>()</a>, <a href="posix_typed_mem_open.html"><i>posix_typed_mem_open</i>()</a> , <a href="sysconf.html"><i>sysconf</i>()</a> , the BaseDefinitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/signal.h.html"><i><signal.h></i></a>, <a href="../basedefs/sys/mman.h.html"><i><sys/mman.h></i></a></p></blockquote><h4><a name="tag_03_400_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 4, Version 2.</p></blockquote><h4><a name="tag_03_400_12"></a>Issue 5</h4><blockquote><p>Moved from X/OPEN UNIX extension to BASE.</p><p>Aligned with <i>munmap</i>() in the POSIX Realtime Extension as follows:</p><ul><li><p>The DESCRIPTION is extensively reworded.</p></li><li><p>The SIGBUS error is no longer permitted to be generated.</p></li></ul></blockquote><h4><a name="tag_03_400_13"></a>Issue 6</h4><blockquote><p>The <i>munmap</i>() function is marked as part of the Memory Mapped Files and Shared Memory Objects option.</p><p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p><ul><li><p>The DESCRIPTION is updated to state that implementations require <i>addr</i> to be a multiple of the page size.</p></li><li><p>The [EINVAL] error conditions are added.</p></li></ul><p>The following changes are made for alignment with IEEE Std 1003.1j-2000:</p><ul><li><p>Semantics for typed memory objects are added to the DESCRIPTION.</p></li><li><p>The <a href="../functions/posix_typed_mem_open.html"><i>posix_typed_mem_open</i>()</a> function is added to the SEE ALSOsection.</p></li></ul><p>IEEE Std 1003.1-2001/Cor 1-2002, item XSH/TC1/D6/36 is applied, changing the margin code in the SYNOPSIS from MF|SHMto MC3 (notation for MF|SHM|TYM).</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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