.\"	$OpenBSD: vm_map_inherit.9,v 1.6 2001/11/06 21:54:41 miod Exp $
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.TH vm_map_inherit 9 9/19/93
.CM 4
.SH NAME
.nf
vm_map_inherit  \-  specifies inheritance of address space
.SH SYNOPSIS
.nf
.ft B
#include <uvm/uvm_map.h>

.nf
.ft B
int	vm_inherit(map, start, end, new_inheritance)
	vm_map_t	map;
	vm_offset_t	start, end;
	vm_inherit_t	new_inheritance;


.fi
.ft P
.SH ARGUMENTS
.TP 15
.B
map
Virtual memory map to be affected.
.TP 15
.B
start
Starting address (will be rounded down to a page
boundary).
.TP 15
.B
end
Ending address (will be rounded down to a page
boundary).
.TP 15
.B
new_inheritance
How this memory is to be inherited in child maps.
Inheritance is specified by using one of these following three values:
.TP 15
.B
VM_INHERIT_SHARE
Child maps will share this memory with this map.
.TP 15
.B
VM_INHERIT_COPY
Child maps will receive a copy of this region.
.TP 15
.B
VM_INHERIT_NONE
This region will be absent from child maps.

.SH DESCRIPTION
.B vm_map_inherit
specifies how a region of a virtual address space
is to be passed to child maps at the time of map creation.
Inheritance is an attribute of virtual pages; thus the addresses
and size of memory to be set will be rounded out to refer to
whole pages.

Setting
.B vm_map_inherit
to
.B VM_INHERIT_SHARE
and forking a child
map is the only way two
.B tasks
can share physical memory.
Remember that all the
.B theads
of a given task share all the same
memory.

.SH DIAGNOSTICS
.TP 25
KERN_SUCCESS
Memory protected.
.TP 25
KERN_INVALID_ADDRESS
Illegal address specified.

.SH SEE ALSO
.B vm_map_fork