This section of the Linux tutorial introduces man pages, the Linux manual pages. The mapping will extend at least len bytes, subject to page alignment restrictions. The addr argument describes the address where the system should place the mapping. If the MAPFIXED flag is specified, the allocation will happen at the specified address, replacing any previously established mappings in its range.
The linux manual page for mmap states: mmap map files or devices into memory# include void mmap(void addr, sizet It maps a file, device or some other definite object to a location in memory. mmap(2) Linux manual page mmap (The Open Group) mmap tutorial (CC) C librarykernel differences This page describes the interface provided by the glibc mmap() wrap per function.
Originally, this function invoked a system call of the same Accesses to notyetloaded parts of the mmapped region are handled in the same way as swapped out pages. Since mmapped pages can be stored back to their file when physical memory is low, it is possible to mmap Mmap linux manual pages orders of magnitude larger than both the physical memory and swap space. The only limit is address space. MAPUNINITIALIZED (since Linux ) Don't clear anonymous pages.
This flag is intended to improve performance on embedded devices. This flag is only honored if the kernel was configured with the option. Because of the security implications, that option is normally enabled only on MAPLOCKED (since Linux ) Lock the pages of the mapped region into memory in the manner of mlock (2).
This flag is ignored in older kernels. MAPNONBLOCK (since Linux ) Only meaningful in conjunction with MAPPOPULATE. Don't perform readahead: only create page tables entries for pages that are already present in RAM. Do I need to keep a file open after calling mmap on it?
Ask Question. The man pages of mmap do not seem terribly clear to me on this one. c mmap. No, at least not on Linux it's fine to close the file. The manual page clearly states: On the other hand, closing the file descriptor does not unmap the region. For portability, I also checked The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
Name mmap map pages of memory