1.\" $NetBSD: minherit.2,v 1.18 2006/10/13 20:52:57 wiz Exp $ 2.\" 3.\" Copyright (c) 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)minherit.2 8.1 (Berkeley) 6/9/93 31.\" 32.Dd October 7, 2006 33.Dt MINHERIT 2 34.Os 35.Sh NAME 36.Nm minherit 37.Nd control the inheritance of pages 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In sys/mman.h 42.Ft int 43.Fn minherit "void *addr" "size_t len" "int inherit" 44.Sh DESCRIPTION 45The 46.Fn minherit 47system call 48changes the specified range of virtual addresses to have the specified 49fork-time inheritance characteristic 50.Fa inherit , 51which can be set to 52.Dv MAP_INHERIT_NONE , 53.Dv MAP_INHERIT_COPY , 54or 55.Dv MAP_INHERIT_SHARE . 56Also possible is 57.Dv MAP_INHERIT_DEFAULT , 58which defaults to 59.Dv MAP_INHERIT_COPY . 60Not all implementations will guarantee that the inheritance characteristic 61can be set on a page basis; 62the granularity of changes may be as large as an entire region. 63.Pp 64Normally, the entire address space is marked 65.Dv MAP_INHERIT_COPY ; 66when the process calls 67.Fn fork , 68the child receives a (virtual) copy of the entire address space. 69Pages or regions marked 70.Dv MAP_INHERIT_SHARE 71are shared between the address spaces, while pages or regions marked 72.Dv MAP_INHERIT_NONE 73will be unmapped in the child. 74.Sh RETURN VALUES 75.Rv -std minherit 76.Sh ERRORS 77.Fn minherit 78will fail if: 79.Bl -tag -width Er 80.It Bq Er EINVAL 81An invalid region or invalid parameters were specified. 82.El 83.Sh SEE ALSO 84.Xr fork 2 , 85.Xr madvise 2 , 86.Xr mincore 2 , 87.Xr mprotect 2 , 88.Xr msync 2 , 89.Xr munmap 2 90.Sh HISTORY 91The 92.Fn minherit 93function first appeared in 94.Ox . 95.Sh BUGS 96If a particular port does not support page-granularity 97inheritance, there's no way to figure out how large a region is 98actually affected by 99.Fn minherit . 100