2 .\" Copyright (c) 1991, 1993
3 .\" The Regents of the University of California. All rights reserved.
5 .\" Redistribution and use in source and binary forms, with or without
6 .\" modification, are permitted provided that the following conditions
8 .\" 1. Redistributions of source code must retain the above copyright
9 .\" notice, this list of conditions and the following disclaimer.
10 .\" 2. Redistributions in binary form must reproduce the above copyright
11 .\" notice, this list of conditions and the following disclaimer in the
12 .\" documentation and/or other materials provided with the distribution.
13 .\" 3. Neither the name of the University nor the names of its contributors
14 .\" may be used to endorse or promote products derived from this software
15 .\" without specific prior written permission.
17 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 .\" @(#)minherit.2 8.1 (Berkeley) 6/9/93
36 .Nd control the inheritance of pages
42 .Fn minherit "void *addr" "size_t len" "int inherit"
47 changes the specified pages to have the inheritance characteristic
49 Not all implementations will guarantee that the inheritance characteristic
50 can be set on a page basis;
51 the granularity of changes may be as large as an entire region.
53 is capable of adjusting inheritance characteristics on a page basis.
54 Inheritance only effects children created by
58 exec'd processes replace their address space entirely.
60 has no effect on the parent's address space (other than to potentially
61 share the address space with its children).
63 Inheritance is a rather esoteric feature largely superseded by the
67 However, it is possible to use
69 to share a block of memory between parent and child that has been mapped
71 That is, modifications made by parent or child are shared but
72 the original underlying file is left untouched.
73 .Bl -tag -width ".Dv INHERIT_SHARE"
75 This option causes the address space in question to be shared between
77 It has no effect on how the original underlying backing
80 This option prevents the address space in question from being inherited
82 The address space will be unmapped in the child.
84 This option causes the child to inherit the address space as copy-on-write.
85 This option also has an unfortunate side effect of causing the parent
86 address space to become copy-on-write when the parent forks.
87 If the original mapping was
89 it will no longer be shared in the parent
90 after the parent forks and there is no way to get the previous
91 shared-backing-store mapping without unmapping and remapping the address
94 This option causes the address space in question to be mapped as new
96 which would be initialized to all zero bytes,
104 system call will fail if:
107 The virtual address range specified by the
111 arguments is not valid.
113 The flags specified by the
115 argument were not valid for the pages specified
133 system call first appeared in
140 support first appeared in
145 Once you set inheritance to
149 there is no way to recover the original copy-on-write semantics
150 short of unmapping and remapping the area.