> real-time executive loop or handling I/O I did some audio implementations on MCUs of all kind, and if I managed to pull out multitracked real-time mixed audi

> real-time executive loop or handling I/O I did some audio implementations on MCUs of all kind, and if I managed to pull out multitracked real-time mixed audio players under 4ms latency, I learn that the real problem here is RAM (other than computing power). Many audio effects requires lot of RAM. Think of how would you do a 5 seconds delay effect, or good quality pitch shifting (FT and inverse FT), reverb, echo, etc. Before you know it, 128KB of RAM is not enough any more. So now you are dreaming about 128MB of RAM (as minimum). If you want to process or output audio from/to network, USB or save the output into a file then you have to add that overhead to the equation. Before you notice it, you'll start looking at small processor like the i.MX28 or the like. Bare-metal BSPs for those processors are quite expensive in terms of code/time. You get what the manufacturer gives to you, and that is, a BSP for Linux.