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.\"	@(#)minherit.2	8.1 (Berkeley) 6/9/93
.\"
.Dd $Mdocdate: January 21 2024 $
.Dt MINHERIT 2
.Os
.Sh NAME
.Nm minherit
.Nd control the inheritance of pages
.Sh SYNOPSIS
.In sys/mman.h
.Ft int
.Fn minherit "void *addr" "size_t len" "int inherit"
.Sh DESCRIPTION
The
.Fn minherit
system call
changes the specified pages to have the inheritance characteristic
.Fa inherit .
A page's inheritance characteristic controls how it will be mapped
in child processes as created by
.Xr fork 2 .
.Pp
The possible inheritance characteristics are:
.Pp
.Bl -tag -width MAP_INHERIT_SHARE -offset indent -compact
.It Dv MAP_INHERIT_NONE
Pages are not mapped in the child process.
.It Dv MAP_INHERIT_COPY
Private copy of pages are mapped in the child process.
.It Dv MAP_INHERIT_SHARE
Mapped pages are shared between the parent and child processes.
.It Dv MAP_INHERIT_ZERO
New anonymous pages (initialized to all zero bytes)
are mapped in the child process.
.El
.Pp
Not all implementations will guarantee that the inheritance characteristic
can be set on a page basis;
the granularity of changes may be as large as an entire region.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
The
.Fn minherit
system call will fail if:
.Bl -tag -width Er
.It Bq Er EPERM
The
.Fa addr
and
.Fa len
parameters specify a region that contains
at least one page which is immutable, or
.Dv MAP_INHERIT_ZERO
is being requested on a page without
.Dv PROT_WRITE
permission.
.It Bq Er EINVAL
The virtual address range specified by the
.Fa addr
and
.Fa len
arguments is not valid.
.It Bq Er EINVAL
The
.Fa inherit
argument is invalid.
.El
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mimmutable 2 ,
.Xr mprotect 2 ,
.Xr msync 2 ,
.Xr munmap 2
.Sh HISTORY
The
.Fn minherit
function first appeared in
.Ox 2.0 .