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Subject: Re: [PATCH 5/6 v5] CPU probe/release files
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Andreas Schwab <schwab@linux-m68k.org>
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Date: Sat, 19 Dec 2009 19:46:55 +1100
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On Fri, 2009-12-18 at 15:33 +0100, Andreas Schwab wrote:
> Nathan Fontenot <nfont@austin.ibm.com> writes:
> 
> > Index: powerpc/arch/powerpc/Kconfig
> > ===================================================================
> > --- powerpc.orig/arch/powerpc/Kconfig	2009-10-28 15:21:47.000000000 -0500
> > +++ powerpc/arch/powerpc/Kconfig	2009-10-28 15:21:53.000000000 -0500
> > @@ -320,6 +320,10 @@
> >  
> >  	  Say N if you are unsure.
> >  
> > +config ARCH_CPU_PROBE_RELEASE
> > +	def_bool y
> > +	depends on HOTPLUG_CPU
> > +
> 
> That does not work.
> 
> drivers/built-in.o: In function `.store_online':
> cpu.c:(.ref.text+0xf5c): undefined reference to `.cpu_hotplug_driver_lock'
> cpu.c:(.ref.text+0xfc8): undefined reference to `.cpu_hotplug_driver_unlock'
> make: *** [.tmp_vmlinux1] Error 1
> 
> cpu_hotplug_driver_lock is only defined on pseries, but HOTPLUG_CPU is
> also defined on pmac.

Well, the stuff was merged ... so we need to fix it.

Nathan, the problem is that the above wlil define ARCH_CPU_PROBE_RELEASE
for any powerpc platform that has HOTPLUG_CPU. So a kernel that doesn't
have pSeries support but has hotplug CPU will have a problem, though for
some reason none of my test configs triggered it (I'll have to check why
next week).

The right approach here is to have cpu_hotplug_driver_lock go through
ppc_md. I suppose, along with some of the other CPU hotplug platform
specific bits.

Cheers,
Ben.