Re: [Xen-merge] Re: [patch] SMP alternatives for i386

[Zwane Mwaikambo]

Hello Keir,

On Wed, 14 Dec 2005, Keir Fraser wrote:

> >  	fixup_irqs(map);
> >  	/* It's now safe to remove this processor from the online map */
> >  	cpu_clear(cpu, cpu_online_map);
> > +
> > +	if (1 == num_online_cpus())
> > +		alternatives_smp_switch(0);
> >  	return 0;
> >  }
> > 
> > Is that really safe there? Ideally you want to do the switch when the
> > processor going offline is no longer executing kernel code.
> 
> Perhaps that check belongs at the end of __cpu_die()? That's where it lives in
> xen's smpboot.c.

Yes indeed, end of __cpu_die would be perfect for x86 too as that's where 
CPU_DEAD acknowledge is checked.

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