Hi, all In the doc GettingStart.txt (rtl2.0), it says that pthread_create() in linux Kernel thread, and so are the functions about the real time fifios. I know that we can not call linux system call in RTL context, because it may corrupt linux' data structure, but why the function above can't ? Thanks for you answers. Linux see: http://www.rtlinux.org/~rtlinux/