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Date: Mon, 17 Aug 2009 11:53:24 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Andi Kleen <andi@firstfloor.org>
CC: Ingo Molnar <mingo@elte.hu>, Mark Kelly <mark@bifferos.com>,
       linux-kernel@vger.kernel.org, Florian Fainelli <florian@openwrt.org>,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [patch] x86 CPU detection for RDC
References: <58001.1250437590@bifferos.com> <20090816155507.GA2791@elte.hu>	<alpine.LNX.2.00.0908160317250.19588@cent.localnet>	<20090816175204.GA28553@elte.hu>	<alpine.LNX.2.00.0908160404300.20653@cent.localnet>	<4A899A1D.8060808@zytor.com> <20090817180825.GA5558@elte.hu>	<4A899FEA.9020707@zytor.com> <871vnas2gn.fsf@basil.nowhere.org>
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On 08/17/2009 11:46 AM, Andi Kleen wrote:
> "H. Peter Anvin" <hpa@zytor.com> writes:
> 
>> On 08/17/2009 11:08 AM, Ingo Molnar wrote:
>>> X86_RDC321X already exists in arch/x86/Kconfig. It should probably 
>>> grow a 'depends on PCI' rline or so.
>>>
>> Sounds like it.
> 
> iirc the patch used early pci which is actually self contained
> in its header. The main problem was that it didn't use it correctly.
> 

It isn't a matter of if compilation works, it is a matter of if we
should even try to probe PCI if the user has explicitly disabled
CONFIG_PCI.  arch/x86/kernel/cpu/cyrix.c disables its PCI probing if
CONFIG_PCI is off, even though it also uses <asm/pci-direct.h>.

Given that the benefit of this CPU detection patch is extremely small
(all it does it get better information in /proc/cpuinfo) and that blind
probing can have disastrous consequences, I would say it should not.

	-hpa