Re: [patch 13/14] x86_64: Use common functions in cluster and physflat mode

[Andi Kleen]

On Fri, Sep 09, 2005 at 10:07:28AM -0700, Zwane Mwaikambo wrote:
> On Tue, 6 Sep 2005, Ashok Raj wrote:
> 
> > On Tue, Sep 06, 2005 at 01:16:28AM +0200, Andi Kleen wrote:
> > > On Sat, Sep 03, 2005 at 02:33:30PM -0700, akpm@xxxxxxxx wrote:
> > > > 
> > > > From: Ashok Raj <ashok.raj@xxxxxxxxx>
> > > > 
> > > > Newly introduced physflat_* shares way too much with cluster with only a very
> > > > differences.  So we introduce some common functions in that can be reused in
> > > > both cases.
> 
> On a slightly different topic, how come we're using physflat for hotplug 
> cpu?

The original idea was to always use physflat mode for hotplug because
that does all the sequencing stuff and avoids the shortcut races.
But then Ashok decided it was better to add more ifdefs to flat mode
instead and I gave up protesting at some point.

-Andi

> 
> -#ifndef CONFIG_CPU_HOTPLUG
>  		/* In the CPU hotplug case we cannot use broadcast mode
>  		   because that opens a race when a CPU is removed.
> -		   Stay at physflat mode in this case.
> -		   It is bad to do this unconditionally though. Once
> -		   we have ACPI platform support for CPU hotplug
> -		   we should detect hotplug capablity from ACPI tables and
> -		   only do this when really needed. -AK */
> +		   Stay at physflat mode in this case. - AK */
> +#ifdef CONFIG_HOTPLUG_CPU
>  		if (num_cpus <= 8)
>  			genapic = &apic_flat;
> 
> Thanks,
> 	Zwane
> 
-
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