linux mmap实例_Linux利用mmap读写物理内存 | 学步园

/*

file: mem.c

function: Read the the first 5 bytes of the memory and then Write it with "HELLO"

*/

#include

#include

#include

#include

#include

#include

int main (int args, char* arg[])

{

int i;

int fd;

char* mem;

char *buff = "HELLO";

//open /dev/mem with read and write mode

if ((fd = open ("/dev/mem", O_RDWR)) < 0)

{

perror ("open error";

return -1;

}

//map physical memory 0-10 bytes

mem = mmap (0, 10, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

if (mem == MAP_FAILED) {

perror ("mmap error:";

return 1;

}

//Read old value

for (i = 0; i < 5; i++)

{

printf("\nold mem[%d]:%d", i, mem[i]);

}

//write memory

memcpy(mem, buff, 5);

//Read new value

for (i = 0; i<5 ; i++)

{

printf("\nnew mem[%d]:%c", i, mem[i]);

}

printf("\n";

munmap (mem, 10); //destroy map memory

close (fd); //close file

return 0;

}

2.编译、运行：

#gcc -o mem mem.c#./mem结果如下：old mem[0]:1old mem[1]:0old mem[2]:0old mem[3]:0old mem[4]:83new mem[0]:Hnew mem[1]:Enew mem[2]:Lnew mem[3]:Lnew mem[4]:O