Here you find an example of communicating between rtlinux rt-threads and userspace applications using /dev/mem. hello.o		rtlinux kernel module that rtl_printf's the value stored in 		shared memory - see hello_func.c for the thread code, run 		dmesg to view output.read_dev_mem 	user-space app reading the value from the same shared memory 		locationwrite_dev_mem 	write integers to /dev/mem, on exit the string quit is entered		which is converted to 0 by atoi so after you type in quite 		shared memory is set to 0.