| | 1 | .\" |
| | 2 | .\" Copyright (c) 2008 Apple Inc. All rights reserved. |
| | 3 | .\" |
| | 4 | .\" @APPLE_LICENSE_HEADER_START@ |
| | 5 | .\" |
| | 6 | .\" This file contains Original Code and/or Modifications of Original Code |
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| | 8 | .\" Version 2.0 (the 'License'). You may not use this file except in |
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| | 11 | .\" file. |
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| | 13 | .\" The Original Code and all software distributed under the License are |
| | 14 | .\" distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
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| | 20 | .\" |
| | 21 | .\" @APPLE_LICENSE_HEADER_END@ |
| | 22 | .\" |
| | 23 | .\" |
| | 24 | .\" $NetBSD: munmap.2,v 1.5 1995/02/27 12:35:03 cgd Exp $ |
| | 25 | .\" |
| | 26 | .\" Copyright (c) 1991, 1993 |
| | 27 | .\" The Regents of the University of California. All rights reserved. |
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| | 32 | .\" 1. Redistributions of source code must retain the above copyright |
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| | 34 | .\" 2. Redistributions in binary form must reproduce the above copyright |
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| | 37 | .\" 3. All advertising materials mentioning features or use of this software |
| | 38 | .\" must display the following acknowledgement: |
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| | 40 | .\" California, Berkeley and its contributors. |
| | 41 | .\" 4. Neither the name of the University nor the names of its contributors |
| | 42 | .\" may be used to endorse or promote products derived from this software |
| | 43 | .\" without specific prior written permission. |
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| | 45 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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| | 47 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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| | 55 | .\" SUCH DAMAGE. |
| | 56 | .\" |
| | 57 | .\" @(#)munmap.2 8.2 (Berkeley) 4/15/94 |
| | 58 | .\" |
| | 59 | .Dd October 16, 2008 |
| | 60 | .Dt MUNMAP 2 |
| | 61 | .Os |
| | 62 | .Sh NAME |
| | 63 | .Nm munmap |
| | 64 | .Nd remove a mapping |
| | 65 | .Sh SYNOPSIS |
| | 66 | .Fd #include <sys/mman.h> |
| | 67 | .Ft int |
| | 68 | .Fo munmap |
| | 69 | .Fa "void *addr" |
| | 70 | .Fa "size_t len" |
| | 71 | .Fc |
| | 72 | .Sh DESCRIPTION |
| | 73 | The |
| | 74 | .Fn munmap |
| | 75 | system call |
| | 76 | deletes the mappings for the specified address range, |
| | 77 | causing further references to addresses within the range |
| | 78 | to generate invalid memory references. |
| | 79 | .Sh DIRTY PAGE HANDLING |
| | 80 | How |
| | 81 | .Fn munmap |
| | 82 | handles a dirty page, depends on what type of memory is being unmapped: |
| | 83 | .Pp |
| | 84 | .Bl -tag -width "[System V Shared]" |
| | 85 | .It Bq Anonymous |
| | 86 | If the memory is anonymous memory and if the last reference is going |
| | 87 | away, then the contents are discarded by definition of anonymous memory. |
| | 88 | .It Bq System V Shared |
| | 89 | If the memory mapping was created using System V shared memory, then |
| | 90 | the contents persist until the System V memory region is destroyed or |
| | 91 | the system is rebooted. |
| | 92 | .It Bq File mapping |
| | 93 | If the mapping maps data from a file (MAP_SHARED), then the memory will |
| | 94 | eventually be written back to disk if it's dirty. This will happen |
| | 95 | automatically at some point in the future (implementation dependent). |
| | 96 | Note: to force the memory to be written back to the disk, use |
| | 97 | .Xr msync 2 . |
| | 98 | .El |
| | 99 | .Pp |
| | 100 | If there are still other references to the memory when the munmap is |
| | 101 | done, then nothing is done to the memory itself and it may be swapped |
| | 102 | out if need be. The memory will continue to persist until the last |
| | 103 | reference goes away (except for System V shared memory in which case, |
| | 104 | see above). |
| | 105 | .Sh RETURN VALUES |
| | 106 | Upon successful completion, |
| | 107 | .Nm munmap |
| | 108 | returns zero. |
| | 109 | Otherwise, a value of -1 is returned and |
| | 110 | .Va errno |
| | 111 | is set to indicate the error. |
| | 112 | .Sh ERRORS |
| | 113 | .Fn munmap |
| | 114 | will fail if: |
| | 115 | .Bl -tag -width Er |
| | 116 | .\" =========== |
| | 117 | .It Bq Er EINVAL |
| | 118 | The |
| | 119 | .Fa addr |
| | 120 | parameter was not page aligned (i.e., a multiple of the page size). |
| | 121 | .\" =========== |
| | 122 | .It Bq Er EINVAL |
| | 123 | The |
| | 124 | .Fa len |
| | 125 | parameter was negative or zero. |
| | 126 | .\" =========== |
| | 127 | .It Bq Er EINVAL |
| | 128 | Some part of the region being unmapped is not part of the currently |
| | 129 | valid address space. |
| | 130 | .El |
| | 131 | .Sh LEGACY SYNOPSIS |
| | 132 | .Fd #include <sys/types.h> |
| | 133 | .Fd #include <sys/mman.h> |
| | 134 | .Pp |
| | 135 | The include file |
| | 136 | .In sys/types.h |
| | 137 | is necessary. |
| | 138 | .Pp |
| | 139 | .Ft int |
| | 140 | .br |
| | 141 | .Fo munmap |
| | 142 | .Fa "caddr_t addr" |
| | 143 | .Fa "size_t len" |
| | 144 | .Fc ; |
| | 145 | .Pp |
| | 146 | The type of |
| | 147 | .Fa addr |
| | 148 | has changed. |
| | 149 | .Sh "SEE ALSO" |
| | 150 | .Xr getpagesize 3 , |
| | 151 | .Xr msync 2 , |
| | 152 | .Xr munmap 2 , |
| | 153 | .Xr mprotect 2 , |
| | 154 | .Xr madvise 2 , |
| | 155 | .Xr mincore 2 , |
| | 156 | .Xr compat 5 |
| | 157 | .Sh HISTORY |
| | 158 | The |
| | 159 | .Fn munmap |
| | 160 | function first appeared in 4.4BSD. |
projects / apple / xnu.git / blame_incremental