Re: [PATCH] cpufreq: Change link order of x86 cpufreq modules

[Ingo Molnar <mingo@elte.hu>]

* Alan Jenkins <sourcejedi.lkml@googlemail.com> wrote:

> On 2/18/09, Ingo Molnar <mingo@elte.hu> wrote:
> >
> > * Matthew Garrett <mjg59@srcf.ucam.org> wrote:
> >
> >> On Wed, Feb 18, 2009 at 07:31:37PM +0100, Ingo Molnar wrote:
> >>
> >> > Nice fix! Where does this information come from? Distro module
> >> > ordering magic? It's rather non-trivial.
> >>
> >> Pretty much. p4-clockmod is never the preferred option because
> >> it does no voltage scaling. speedstep-centrino is now almost
> >> entirely functionally replaced with acpi-cpufreq. The
> >> powernow-k8 issue was a personal communication from davej.
> >
> > I'm wondering whether that priority order should/could be
> > expressed in the module space too - so that distros wouldnt have
> > to replicate this. This is really a piece of information the
> > kernel is best at maintaining.
> 
> The latest development version of module-init-tools (in the 
> git tree) is designed to preserve the kernel link order when 
> resolving builtin aliases.  If you have two modules which 
> provide the alias "pci:123", they will be loaded in the same 
> order as if they were builtin drivers.

very nifty ...

> It should work if all the cpufreq drivers provide an alias 
> "cpufreq-driver" and userspace just does "modprobe 
> cpufreq-driver". You just need to be sure none of the cpufreq 
> drivers provide *other* aliases which cause them to be loaded 
> earlier, by udev or some other bootscript.

yeah. Nice.

	Ingo