MREMAP(2)

MREMAP(2) | System Calls Manual | MREMAP(2)

# NAME

mremap — re-map a virtual memory address

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

#include <sys/mman.h>
void *
mremap(void *oldp, size_t oldsize, void *newp, size_t newsize, int flags);

# DESCRIPTION

The mremap() function resizes the mapped range (see mmap(2)) starting at oldp and having size oldsize to newsize. The following arguments can be `OR`'ed together in the flags argument:

`MAP_ALIGNED`(n)
  The allocation should be aligned to the given boundary, i.e. ensure that the lowest n bits of the address are zero. The parameter n should be the base 2 logarithm of the desired alignment (e.g., to request alignment to 16K, use 14 as the value for n). The alignment must be equal to or greater than the platform's page size as returned by sysconf(3) with the `_SC_PAGESIZE` request.
`MAP_FIXED`
  newp is tried and mremap() fails if that address can't be used as new base address for the range. Otherwise, oldp and newp are used as hints for the position, factoring in the given alignment.
`MAP_REMAPDUP`
  Duplicate the mapping. Both address ranges reference the same pages, but can have different protection flags.

# RETURN VALUES

mremap() returns the new address or `MAP_FAILED`, if the remap failed.

# COMPATIBILITY

The semantics of mremap() differ from the one provided by glibc on Linux in that the newp argument was added and a different set of flags are implemented.

# SEE ALSO

mmap(2), munmap(2)

# HISTORY

The mremap() system call appeared in NetBSD 5.0. It was based on the code that supports mremap() compatibility for Linux binaries.

April 28, 2017 | NetBSD 8.0