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

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Date:	Tue, 5 Apr 2016 04:20:47 +0000
From:	"Brown, Len" <len.brown@...el.com>
To:	"rcochran@...utronix.de" <rcochran@...utronix.de>,
	"Gortmaker, Paul (Wind River)" <paul.gortmaker@...driver.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Len Brown <lenb@...nel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: RE: [PATCH] drivers/idle: make intel_idle.c driver more explicitly
 non-modular

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.