MAP_SHARED_VALIDATE, the kernel verifies all passed flagsĪre known and fails the mapping with the error EOPNOTSUPPįor unknown flags. That MAP_SHARED mappings ignore unknown flags in flags.īy contrast, when creating a mapping using This flag provides the same behavior as MAP_SHARED except (To precisely control when updates areĬarried through to the underlying file requires the use of Of file-backed mappings) are carried through to the Other processes mapping the same region, and (in the case Thisīehavior is determined by including exactly one of the following Updates are carried through to the underlying file. Visible to other processes mapping the same region, and whether The flags argument determines whether updates to the mapping are It is either PROT_NONE or the bitwise OR of one or more of the Mapping (and must not conflict with the open mode of the file). The prot argument describes the desired memory protection of the Of the page size as returned by sysconf(_SC_PAGE_SIZE).Īfter the mmap() call has returned, the file descriptor, fd, canīe closed immediately without invalidating the mapping. Mapping see MAP_ANONYMOUS below), are initialized using lengthīytes starting at offset offset in the file (or other object) The contents of a file mapping (as opposed to an anonymous TheĪddress of the new mapping is returned as the result of the call. If another mapping already exists there, the kernel picksĪ new address that may or may not depend on the hint. proc/sys/vm/mmap_min_addr) and attempt to create the mapping Linux, the kernel will pick a nearby page boundary (but always Kernel takes it as a hint about where to place the mapping on If addr is NULL, then the kernel chooses the (page-aligned)Īddress at which to create the mapping this is the most portable The mapping (which must be greater than 0). The length argument specifies the length of The starting address for the new mapping is See NOTES for information on feature test macro requirements.ĭESCRIPTION top mmap() creates a new mapping in the virtual address space of theĬalling process. SYNOPSIS top #include void *mmap(void addr, size_t length, int prot, int flags, int fd, off_t offset ) int munmap(void addr, size_t length ) Mmap, munmap - map or unmap files or devices into memory Mmap(2) System Calls Manual mmap(2) NAME top
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