Re: [PATCH] x86_64: not set boot cpu in cpu_online_map atsmp_prepare_boot_cpu

[Yinghai Lu]

Zachary Amsden wrote:
> On Mon, 2007-11-26 at 00:38 -0800, Yinghai Lu wrote:
> > [PATCH] x86_64: not set boot cpu in cpu_online_map at smp_prepare_boot_cpu
> >
> > in init/main.c boot_cpu_init() does that before
> >
> > Signed-off-by: Yinghai Lu <yinghai.lu@xxxxxxx>
> >
> > diff --git a/arch/x86/kernel/smpboot_64.c b/arch/x86/kernel/smpboot_64.c
> > index 500670c..966d124 100644
> > --- a/arch/x86/kernel/smpboot_64.c
> > +++ b/arch/x86/kernel/smpboot_64.c
> > @@ -912,7 +912,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> >  void __init smp_prepare_boot_cpu(void)
> >  {
> >  	int me = smp_processor_id();
> > -	cpu_set(me, cpu_online_map);
> > +	/* already set me in cpu_online_map in boot_cpu_init() */
> >  	cpu_set(me, cpu_callout_map);
> >  	per_cpu(cpu_state, me) = CPU_ONLINE;
> >  }
>
>
> This ordering can be tricky wrt CPU hotplug.  Are you sure you are not
> breaking CPU hotplug?  AFAIK, x86_64 has that right and the 32-bit code
> had it wrong.


CPU hot plug path will call smp_prepare_boot_cpu?
it is using __init instead of __cpuinit?

YH
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