Re: [v8 PATCH 2/8]: cpuidle: implement a list based approach to register a set of idle routines.

* Andi Kleen [off-list ref] [2009-10-14 09:18:38]:

quoted

How about something like this..
If the arch does not enable CONFIG_CPU_IDLE, the cpuidle_idle_call
which is called from cpu_idle() should call default_idle without
involving the registering cpuidle steps. This should prevent bloating
up of the kernel for archs which dont want to use cpuidle.

On x86 some people want small kernel too, so selecting it on a architecture
granuality is not good. Also you can make it default, you just need
to slim it down first.

No, I dont mean selecting it on an architecture granularity.

At compile time, if CONFIG_CPU_IDLE is disabled, the arch can redefine
cpuidle_idle_call. For e.g. in arch/x86/kernel/process.c

#ifndef CONFIG_CPU_IDLE
void cpuidle_idle_call(void)
{
	if (local_idle)
		local_idle();
	else
		default_idle();
}
#endif

where local_idle points to the idle routine selected using
select_idle_routine() which can be poll, mwait, c1e.

So this way, we still preserve the exact same functionality as before
and we also remove the ugly pm_idle exported function pointer and we
avoid unnecessary code bloat for platforms who do not want to use
cpuidle.

--arun