84 lines
3.2 KiB
Groff
84 lines
3.2 KiB
Groff
.\" $NetBSD: minherit.2,v 1.6 2000/06/26 17:00:01 kleink Exp $
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.\"
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.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)minherit.2 8.1 (Berkeley) 6/9/93
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.\"
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.Dd June 9, 1993
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.Dt MINHERIT 2
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.Os
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.Sh NAME
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.Nm minherit
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.Nd control the inheritance of pages
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include <sys/mman.h>
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.Ft int
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.Fn minherit "void *addr" "size_t len" "int inherit"
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.Sh DESCRIPTION
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The
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.Fn minherit
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system call
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changes the specified range of virtual addresses to have the specified
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fork-time inheritance characteristic
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.Fa inherit ,
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which can be set to VM_INHERIT_NONE, VM_INHERIT_COPY, or VM_INHERIT_SHARE.
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Not all implementations will guarantee that the inheritance characteristic
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can be set on a page basis;
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the granularity of changes may be as large as an entire region.
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.Pp
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Normally, the entire address space is marked VM_INHERIT_COPY; when the
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process calls
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.Fn fork ,
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the child receives a (virtual) copy of the entire address space.
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Pages or regions marked VM_INHERIT_SHARE are shared between the
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address spaces, while pages or regions marked VM_INHERIT_NONE will be
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unmapped in the child.
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.Sh BUGS
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If the a particular port does not support page-granularity
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inheritance, there's no way to figure out how large a region is
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actually affected by
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.Fn minherit .
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.Sh SEE ALSO
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.Xr fork 2 ,
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.Xr madvise 2 ,
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.Xr mincore 2 ,
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.Xr mprotect 2 ,
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.Xr msync 2 ,
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.Xr munmap 2
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.Sh HISTORY
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The
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.Fn minherit
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function first appeared in
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.Bx Open .
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