This provides a more robust and efficient implementation that only forces memory reloads
at explicit known points, instead of the over approximation of every time they are
accessed that is forced by volatile.
- Restart TCB from inside the lock if it is waiting for anything other than IRQ
- Only replace the TCB with idle thread if it is in ThreadState_RunningVM state
Also, this makes the design generic to be shared with arm.
Currently building ARM/SMP is broken. This commit:
1- Makes it possible to build ARM/SMP with stubs. Run-time SMP for ARM
DOES NOT WORK.
2- Can be a reference for future SMP targets to follow in order to
layout/add the minimal required files and functions needed to support SMP.
3- Builds for Sabre only. In order to support other platforms, ipi
interrupt ID should be defined in machine.h
This commit is a re-arrangement of SMP directory structure to make it
easier for other architectures/platforms (in general) and ARM (in
particular) to add SMP support.
* new include/smp directory to act as a centralised container of
"shared" architecture-independent SMP headers.
This makes it clearer what's needed for other architecture/platform to
support SMP.
* Each platform can define its own unique ipi.[h|c] that make sense,
since ipi implementation is SoC/platform dependent.
