Subject: Re: CPU specific Idle() function in locore_subr.S
To: Tim Kelly <>
From: Allen Briggs <>
List: port-powerpc
Date: 01/23/2005 16:25:22
On Sun, Jan 23, 2005 at 09:51:51AM -0500, Tim Kelly wrote:
> I was looking at this again, and I see that the initial value of
> ci_idlespin is "blr" which just returns afters the bctrl in Idle(). In
> cpu_attach_common from cpu_subr.c this is overridden with the idlespin
> routine that checks powersave is greater than zero before setting
> MSR[POW]. Are there cases in which one would want to turn powersave off 
> for some periods but not others, in which case one would want an
> idlespin routine installed? Otherwise, why not leave ci_idlespin as blr
> when there will be no use (at all) of MSR[POW]?

powersave is a sysctl'able variable, so it's under control of the system
administrator.  I think it's reasonable to ask if system administrators
should have control over it.  I'm inclined to say that they should.


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