My last experience with rt-linux teached me that the kernel is not the only thing that needs to support real-time. As soon as you have any drivers (DMA!) or e.g

My last experience with rt-linux teached me that the kernel is not the only thing that needs to support real-time. As soon as you have any drivers (DMA!) or e.g. Service Management Interrupts (SMIs) that circumvent any smart preemptive scheduler of the kernel you're still screwed. So, what was said is correct, hard real-time is hard, and an OS on top of a "general purpose" hardware platform makes it harder. That being said, there is stuff like VxWorks, which kind of proves that it is possible, if you have full control over the hardware and the OS.