The first idle driver to register with cpuidle wins. intel_idle should always get the opportunity to probe and register before acpi_idle (processor_idle.c)
When intel_idle was allowed to be modular, some distros build their kernel and loaded modules such that acpi_idle could probe first. In such a kernel, intel_idle became dead code. As intel_idle is a small driver, the q uick fix was to make it Y/N so that it would always probe before acpi_idle, no matter how acpi_idle is build and loaded. Yes, even though intel_idle is a tiny driver, I think it would be good to be able to unload it when it doesn't probe. Today, it appears that acpi_idle (acpi/processor_idle.c) is compiled Y/N. thanks, -Len ps. No, I do not believe that cpuidle should bother supporting changing idle drivers at run-time.