#include #include #include #include #include #include #include #define CHAR_IOCTL 0x1a #define I_CHAR_MMAP _IOWR(CHAR_IOCTL, 1,1024) main() { int fd=0; unsigned long buffer; char *buf; int rc=0; char towrite; fd = open("/dev/simplechar",O_RDWR); if(fd <0){ perror("Open failed"); return; } printf("buffer ptr:%p\n", buffer); rc = ioctl (fd, I_CHAR_MMAP,&buffer); if(rc ) { perror("mmap"); return; } printf("buffer pointr:%p\n",buffer); printf(" buffer is:%s\n", (char *)buffer); // strcpy((char*)buffer,"hi meri"); }