minherit(2) - NetBSD Manual Pages

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MINHERIT(2)               NetBSD System Calls Manual               MINHERIT(2)

minherit -- control the inheritance of pages
Standard C Library (libc, -lc)
#include <sys/mman.h> int minherit(void *addr, size_t len, int inherit);
The minherit() system call changes the specified range of virtual addresses to have the inheritance characteristic inherit, which deter- mines how fork(2) will map the region in the child process. The sup- ported inheritance characteristics are: MAP_INHERIT_COPY The child is given a private copy of the region: writes from parent or child are not seen by the other. MAP_INHERIT_NONE The region is unmapped in the child. MAP_INHERIT_SHARE The child is shares the region with the parent: writes from parent and child are seen by both. MAP_INHERIT_ZERO The region is mapped in the child to anonymous pages filled with zeros. Normally, the parent's virtual address space is copied for the child as if with MAP_INHERIT_COPY, for which the alias MAP_INHERIT_DEFAULT is pro- vided. Regions in the parent mapped using mmap(2) with the MAP_SHARED flag are by default shared with the child as if with MAP_INHERIT_SHARED. Not all implementations will guarantee that the inheritance characteris- tic can be set on a page basis; the granularity of changes may be as large as an entire region.
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.
minherit() will fail if: [EINVAL] An invalid region or invalid parameters were speci- fied.
fork(2), madvise(2), mincore(2), mmap(2), mprotect(2), msync(2), munmap(2)
The minherit() function first appeared in OpenBSD 2.0, then NetBSD 1.3.
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(). NetBSD 9.99 September 8, 2019 NetBSD 9.99
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