"hard" real-time. But it makes it soft real-time and good enough for many applications. Yes, you would use a different kernel that was compiled with this enabled. By default it still reserves some time for user-space processes that haven't been switched to the RT scheduler if any. So even if you used this on your desktop it would still mostly function normally. But when you're using it as an RTOS you would choose the RT scheduler and select a priority for each process.