mmap - manipulate process virtual address space
Synopsis
Description
#include <sys/mman.h>
int mmap(void *vaddr, ulong len, int prot, int flags, int fd, ulong offset);
The mmap() system call manipulates the address space of a process. In general, len bytes of mapped space is created, and is mapped in at the specified vaddr. The vaddr can be (void *)0, and the OS will choose an address. MAP_FIXED, specified below, also affects address assignment.The protection of the mapped space is controlled by the prot parameters, with the following bits defined:
#define PROT_EXEC (0x01) #define PROT_READ (0x02) #define PROT_WRITE (0x04)flags controls the contents of the memory space created by mmap(), and may contain the following options:
#define MAP_ANON (0x01) #define MAP_FILE (0x02) #define MAP_FIXED (0x04) #define MAP_PRIVATE (0x08) #define MAP_SHARED (0x10) #define MAP_PHYS (0x20)MAP_ANON specifies "anonymous" memory; this is memory which is filled on demand with an initial contents of zero.
MAP_FILE creates memory whose contents is initially filled from the file specified by the fd parameter. The contents is filled from offset bytes into the file.
MAP_FIXED requires that the new memory object be mapped exactly at the address specified by vaddr; otherwise, the request fails.
MAP_PRIVATE creates a memory objects in which any changes to the initial contents are not reflected in the object as viewed in any other address space.
MAP_SHARED is the opposite of MAP_PRIVATE; this option is not supported for writable memory segments in VSTa.
MAP_PHYS creates a view into physical memory; it is generally used by device drivers. In this case, vaddr is instead the physical address to map. The attached memory is always mapped in at an OS-chosen address.
| MMAP (2) |