mmap () creates a new mapping in the virtual address space of the calling process. The starting address for the new mapping is specified in addr. The length argument specifies the length of the mapping (which must be greater than 0).

In computing, mmap(2) is a POSIX -compliant Unix system call that maps files or devices into memory. It is a method of memory-mapped file I/O. It implements demand paging because file contents are not immediately read from disk and initially use no physical RAM at all.

Oct 6, 2023 · Memory mapping or mmap () is a function call in an Operating system like Unix. It is a low-level language, and it helps to directly map a file to the currently executing process’s own memory address space.

mmap () creates a new mapping in the virtual address space of the calling process. The starting address for the new mapping is specified in addr. The length argument specifies the length of the mapping. If addr is NULL, then the kernel chooses the address at which to create the mapping; this is the most portable method of creating a new mapping.

Dec 30, 2024 · mmap (memory-mapped file) is a system call that maps a file or a portion of it into a process’s virtual memory space. This allows a program to directly access file data as if it were part of the program’s memory, bypassing explicit read and write system calls.

Oct 24, 2023 · The mmap() ("memory map") system call maps files, devices, or anonymous memory into the virtual address space of a process. Once mapped, the process can directly access the mapped memory just like accessing regular arrays.

The mmap2 () system call provides the same interface as mmap (2), except that the final argument specifies the offset into the file in 4096-byte units (instead of bytes, as is done by mmap (2)). This enables applications that use a 32-bit off_t to map large files (up to 2^44 bytes).

Learn about the mmap system call in Unix, its usage, parameters, and examples to effectively map files or devices into memory.

Sep 27, 2024 · In this guide, we‘ve explored the fundamentals of mmap and how it relates to virtual memory in Linux. We‘ve looked at real-world usage statistics, analyzed performance data, and discussed advanced features like huge pages and non-blocking mode.

Mar 24, 2022 · This article first introduces the process address space and mmap, then analyzes the kernel code to understand its implementation, and finally deepens the understanding of mmap with a simple demo driver example.