
Here you find an example of communicating between rtlinux rt-threads and user
space 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 
		location

write_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.
