From mboxrd@z Thu Jan  1 00:00:00 1970
From: Khalid Aziz <khalid_aziz@hp.com>
Date: Tue, 14 Mar 2006 16:00:15 +0000
Subject: Re: [PATCH] kexec for ia64
Message-Id: <1142352015.18421.3.camel@lyra.fc.hp.com>
List-Id: <linux-ia64.vger.kernel.org>
References: <1142271576.10787.15.camel@lyra.fc.hp.com>
	 <20060313224404.1133fc28.akpm@osdl.org>
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To: Andrew Morton <akpm@osdl.org>
Cc: Fastboot mailing list <fastboot@lists.osdl.org>, Linux ia64 <linux-ia64@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, "Luck, Tony" <tony.luck@intel.com>

On Mon, 2006-03-13 at 22:44 -0800, Andrew Morton wrote:
> Khalid Aziz <khalid_aziz@hp.com> wrote:
> > +	int cpu;
> > +
> > +	for_each_online_cpu(cpu) {
> > +		if (cpu != smp_processor_id())
> > +			cpu_down(cpu);
> > +	}
> > +#else
> > +	smp_call_function(kexec_stop_this_cpu, (void *)image->start, 0, 0);
> > +#endif
> > +#endif
> 
> Why is different code needed for hotplug cpu?

Hi Andrew,

It is preferable to use cpu_down() to shoot down a cpu, but this
function is available only with CONFIG_HOTPLUG_CPU. If
CONFIG_HOTPLUG_CPU is not enabled, only other way to shut down slave
CPUs in a state where they would come back up when the new kernel boots
up and sends them IPI is to hold them in a fake rendezvous which is what
the function kexec_stop_this_cpu() does. So the choices are either to
keep both ways of shutting down CPUs or go with kexec_stop_this_cpu()
for all cases.

Thanks for the comments. I will move declarations to header files as you
suggested.

-- 
Khalid

==================================
Khalid Aziz                       Open Source and Linux Organization
(970)898-9214                                        Hewlett-Packard
khalid.aziz@hp.com                                  Fort Collins, CO

"The Linux kernel is subject to relentless development" 
                                - Alessandro Rubini