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Re: [Xen-devel] Re: [RFC PATCH V4 2/5] cpuidle: list based cpuidle drive

To: Len Brown <lenb@xxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [RFC PATCH V4 2/5] cpuidle: list based cpuidle driver registration and selection
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Fri, 25 Mar 2011 11:35:24 -0400
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On Fri, Mar 25, 2011 at 03:05:36AM -0400, Len Brown wrote:
> > I think there are other problems too, related to saving and restoring
> > of pm_idle pointer. For example, cpuidle itself saves current value
> > of pm_idle, flips it and then restores the saved value. There is
> > no guarantee that the saved function still exists. APM does exact
> > same thing (though it may not be used these days).
> > 
> > The problem also is that a number of architectures have copied the
> > same design based on pm_idle; so its spreading.
> pm_idle is a primitive design yes, but I think the issue
> with pm_idle is a theoretical one, at least on x86;
> as there isn't any other code scribbling on pm_idle
> in practice.  So this is clean-up, rather than bug-fix work...
> > > It isn't immediately clear to me that all of these options
> > > need to be preserved.
> > 
> > So what do you suggest can be removed?
> I sent a series of small patches yesterday to get the ball rolling...
> https://lkml.org/lkml/2011/3/24/54
> I think the xen thing can go away.

The xen thing being the setting of cpuidle to halt or the proposed

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