Re: [PATCH] drivers/idle: make intel_idle.c driver more explicitly non-modular

From: rcochran
Date: Tue Apr 05 2016 - 00:30:29 EST


On Tue, Apr 05, 2016 at 04:20:47AM +0000, Brown, Len wrote:
> 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.

And that means fixing the race with acpi_idle, right?

> Today, it appears that acpi_idle (acpi/processor_idle.c)
> is compiled Y/N.

So it, too, needs work?

> No, I do not believe that cpuidle should bother
> supporting changing idle drivers at run-time.

Huh? But you just said, "it would be good to be able to unload it
when it doesn't probe."

Thanks,
Richard