What is mmap?
mmap is a system call that creates a new mapping in the virtual address space of the calling process at fd.
#include <sys/mman.h>
void *mmap(void *addr, size_t length, int prot, int flags,
int fd, off_t offset);The protection flags include:
PROT_EXEC
- Pages may be executed.
PROT_READ
- Pages may be read.
PROT_WRITE
- Pages may be written.
PROT_NONE
- Pages may not be accessed.
some interesting flags:
MAP_ANONYMOUS: The mapping is not backed by a file.
MAP_FIXED_NOREPLACE: Put the mapping at the location provided by addr, but dont overwrite any existing mappings.
MAP_HUGE_2MB MAP_HUGE_1GB: Map 2MB or 1GB huge pages. You may map different page sizes by bitshifting MAP_HUGE_SHIFT.