Hi, This is actually tested code; but still missing the SMP wake-to-idle machinery. I still need to think about that. I'll post my test-hack as a reply, but basically it does co-operative and preemptive UP-like user scheduling. Patches go on top of tip/master as they rely on the .fixup removal recently merged in tip/x86/core. Also, I still need to audit a bunch of mm code, because I'm not sure things are actually as well behaved as this code supposes they are.
