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31.\"	@(#)minherit.2	8.1 (Berkeley) 6/9/93
32.\"
33.Dd $Mdocdate: July 13 2014 $
34.Dt MINHERIT 2
35.Os
36.Sh NAME
37.Nm minherit
38.Nd control the inheritance of pages
39.Sh SYNOPSIS
40.In sys/mman.h
41.Ft int
42.Fn minherit "void *addr" "size_t len" "int inherit"
43.Sh DESCRIPTION
44The
45.Fn minherit
46system call
47changes the specified pages to have the inheritance characteristic
48.Fa inherit .
49A page's inheritance characteristic controls how it will be mapped
50in child processes as created by
51.Xr fork 2 .
52.Pp
53The possible inheritance characteristics are:
54.Pp
55.Bl -tag -width MAP_INHERIT_SHARE -offset indent -compact
56.It Dv MAP_INHERIT_NONE
57Pages are not mapped in the child process.
58.It Dv MAP_INHERIT_COPY
59Private copy of pages are mapped in the child process.
60.It Dv MAP_INHERIT_SHARE
61Mapped pages are shared between the parent and child processes.
62.It Dv MAP_INHERIT_ZERO
63New anonymous pages (initialized to all zero bytes)
64are mapped in the child process.
65.El
66.Pp
67Not all implementations will guarantee that the inheritance characteristic
68can be set on a page basis;
69the granularity of changes may be as large as an entire region.
70.Sh RETURN VALUES
71.Rv -std minherit
72.Sh ERRORS
73The
74.Fn minherit
75system call will fail if:
76.Bl -tag -width Er
77.It Bq Er EINVAL
78The virtual address range specified by the
79.Fa addr
80and
81.Fa len
82arguments is not valid.
83.It Bq Er EINVAL
84The
85.Fa inherit
86argument is invalid.
87.El
88.Sh SEE ALSO
89.Xr madvise 2 ,
90.Xr mincore 2 ,
91.Xr mprotect 2 ,
92.Xr msync 2 ,
93.Xr munmap 2
94.Sh HISTORY
95The
96.Fn minherit
97function first appeared in
98.Ox 2.0 .
99The
100.Dv MAP_INHERIT_ZERO
101flag first appeared in
102.Ox 5.6 .
103