Use "cpu" for an arbitrary Per_CPU_Control variable.
Use "cpu_self" for the Per_CPU_Control of the current processor.
Use "cpu_index" for an arbitrary processor index.
Use "cpu_index_self" for the processor index of the current processor.
Use "cpu_count" for the processor count obtained via
_SMP_Get_processor_count().
Use "cpu_max" for the processor maximum obtained by
rtems_configuration_get_maximum_processors().
Add _Debug_Is_thread_dispatching_allowed(). This makes it possible to
assert the opposite.
Use _ISR_Disable_without_giant()/_ISR_Enable_without_giant() to avoid
misleading secondary assertion failures.
