NAME

minherit — control the inheritance of pages

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/mman.h>

int
minherit(void *addr, size_t len, int inherit);

DESCRIPTION

The minherit() system call changes the specified range of virtual addresses to have the specified fork-time inheritance characteristic inherit, which can be set to MAP_INHERIT_NONE, MAP_INHERIT_COPY, or MAP_INHERIT_SHARE. Also possible is MAP_INHERIT_DEFAULT, which defaults to MAP_INHERIT_COPY. 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.

Normally, the entire address space is marked MAP_INHERIT_COPY; when the process calls fork(), the child receives a (virtual) copy of the entire address space. Pages or regions marked MAP_INHERIT_SHARE are shared between the address spaces, while pages or regions marked MAP_INHERIT_NONE will be unmapped in the child.

RETURN VALUES

The minherit() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

ERRORS

minherit() will fail if:

[EINVAL]

An invalid region or invalid parameters were specified.

SEE ALSO

fork(2), madvise(2), mincore(2), mprotect(2), msync(2), munmap(2)

HISTORY

The minherit() function first appeared in OpenBSD.

BUGS

If a particular port does not support page-granularity inheritance, there's no way to figure out how large a region is actually affected by minherit().