RE: [Fastboot] [PATCH] kexec: Fix CONFIG_SMP=n compilation (ia64)

[Zou, Nanhai]

> -----Original Message-----
> From: Horms [mailto:horms@xxxxxxxxxxxx]
> Sent: 2007年2月3日 11:28
> To: Magnus Damm
> Cc: Andrew Morton; Magnus Damm; Luck, Tony; linux-ia64@xxxxxxxxxxxxxxx; Zou,
> Nanhai; fastboot@xxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [Fastboot] [PATCH] kexec: Fix CONFIG_SMP=n compilation (ia64)
> 
> On Fri, Feb 02, 2007 at 08:53:00PM +0900, Magnus Damm wrote:
> > On 2/2/07, Magnus Damm <magnus.damm@xxxxxxxxx> wrote:
> > > On 2/2/07, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> > > > Magnus Damm <magnus@xxxxxxxxxxxxx> wrote:
> > > >
> > > > > kexec: Fix CONFIG_SMP=n compilation (ia64)
> > > > >
> > > > > This patch makes it possible to compile kexec for ia64 without SMP
> support.
> > > > > --- 0002/arch/ia64/kernel/machine_kexec.c
> > > > > +++ work/arch/ia64/kernel/machine_kexec.c     2007-02-01
> 12:35:46.000000000 +0900
> > > > > @@ -70,12 +70,14 @@ void machine_kexec_cleanup(struct kimage
> > > > >
> > > > >  void machine_shutdown(void)
> > > > >  {
> > > > > +#ifdef CONFIG_SMP
> > > > >       int cpu;
> > > > >
> > > > >       for_each_online_cpu(cpu) {
> > > > >               if (cpu != smp_processor_id())
> > > > >                       cpu_down(cpu);
> > > > >       }
> > > > > +#endif
> > > > >       kexec_disable_iosapic();
> > > > >  }
> > > >
> > > > hm.  I suspect this one should have been #ifndef CONFIG_HOTPLUG_CPU?
> >
> > Re-reading this I assume you mean #ifdef CONFIG_HOTPLUG_CPU.
> >
> > I would be happy to resend a new updated version of the patch, but I
> > wonder if it may be better to fail miserably during the build than
> > fail silently in the case of CONFIG_SMP=y but CONFIG_HOTPLUG_CPU=n.
> 
> There used to be alternate code for the CONFIG_SMP +
> !CONFIG_HOTPLUG_CPU, but this was removed because it was determined to
> be flakey and not maintainable (I can dig up the threads if you want).
> I think that this means that if we have CONFIG_KEXEC and CONFIG_SMP then
> CONFIG_HOTPLUG_CPU is required. I think this is expressable in Kconfig
> somehow.
> 


Yes, CONFIG_HOTPLUG_CPU is required by Kexec.
But CONFIG_HOTPLUG_CPU is not required by Kdump except SN platform.

Zou Nan hai
> --
> Horms
>   H: http://www.vergenet.net/~horms/
>   W: http://www.valinux.co.jp/en/
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