Beginners • memory mapping hardware (Clo)

Code:

$ sudo chmod 644 /dev/mem $ ls -ld /dev/memcrw-r--r-- 1 root kmem 1, 1 Jan 29 10:55 /dev/mem$ ./boottimeunable to open /dev/mem: Operation not permitted

Code:

iint main(int argc, char **argv) {  int fd = open("/dev/mem", O_RDONLY);  if (fd == -1) {    perror("unable to open /dev/mem");    return 2;  }  uint64_t physaddr;  // physaddr = 0x20000000; // bcm2835  // physaddr = 0xfe000000; // bcm2711  physaddr = 0x1000000000; // bcm2712  //physaddr = bcm_host_get_peripheral_address();  //printf("addr %lx\n", physaddr);  void *addr = mmap(NULL, 16 * 1024 * 1024, PROT_READ, MAP_SHARED, fd, physaddr);  if (addr == MAP_FAILED) {    perror("unable to mmap");    return 1;  }