CPU plugins are code fragment resources that allow the NanoKernel to
perform CPU-specific functions, such as starting or stopping a processor
core or getting core temperature. They live in the Apple CPU Plugins
file. The Power Manager selects a plugin at boot (or doesn't), prepares
and holds it in memory, and registers it with the NanoKernel using
MPRegisterCpuPlugin(). The NanoKernel can then call any of the plugin's
entry points synchronously using its SIGP() function, which is also
exposed via the MPCpuPlugin() call. The plugin return path is tricky,
but involved the ReturnFromInterrupt trap instruction in the emulator
ROM code.
The CPU plugin calling convention is described in the SIGP comments. CPU
plugins operate in the blue address space, but with interrupts disabled
and supervisor mode on.
This code was reversed to get the Mac mini working. It is not clear how
the Power Manager determines CPU temperature when there are no CPU
registers to do this.
Namely queues, semaphores, critical regions, event groups and
"notifications". The MP calls implementing these services have been
named after their MPLibrary wrapper functions. This convention will be
followed in the future (no more NKCreateEvent).
