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Date: Mon, 08 May 2006 17:16:34 -0700
From: Geoff Levand <geoffrey.levand@am.sony.com>
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To: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [patch] powerpc: remove do-nothing cpu setup routines
References: <BE9739CD-B66A-43A4-B5E9-2DE49CEDE5B7@kernel.crashing.org>
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Cc: "Levand, Geoffrey" <Geoffrey.Levand@am.sony.com>,
	Arnd Bergmann <arnd@arndb.de>, linuxppc-dev@ozlabs.org,
	Paul Mackerras <paulus@samba.org>, cbe-oss-dev@ozlabs.org
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Segher Boessenkool wrote:
>>> Removes the processor specific do-nothing routines  
>>> __setup_cpu_power3 and
>>> __setup_cpu_power4 with the generic routine __setup_cpu_null.
>>
>> Why not just change the caller to test for NULL ?

OK, I see the 32 bit version already does this, but I'm
wondering if there is some restriction on the instruction
sequence between the compare and the branch.  Here's what's
there:

	lwz	r5,CPU_SPEC_SETUP(r4)
	cmpi	0,r5,0
	add	r5,r5,r3
	beqlr
	mtctr	r5
	bctr

But, could this also be:

	lwz	r5,CPU_SPEC_SETUP(r4)
	cmpi	0,r5,0
	beqlr
	add	r5,r5,r3
	mtctr	r5
	bctr

-Geoff