Message-ID: <5085AD7D.106@zytor.com>
Date: Mon, 22 Oct 2012 13:33:01 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: "Eric W. Biederman" <ebiederm@xmission.com>
CC: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>, linux-kernel@vger.kernel.org,
        kexec@lists.infradead.org, x86@kernel.org, mingo@elte.hu,
        tglx@linutronix.de, len.brown@intel.com, fenghua.yu@intel.com,
        vgoyal@redhat.com, grant.likely@secretlab.ca, rob.herring@calxeda.com
Subject: Re: [PATCH v1 2/2] x86, apic: Disable BSP if boot cpu is AP
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On 10/22/2012 01:31 PM, Eric W. Biederman wrote:
>>
>> IIRC Fenghua experimented with that and it didn't work.  Not all BIOSes
>> use that bit to determine BSP-ness.
> 
> What does a BIOS have to do with anything?
> 
> The practical issue here is does an INIT IPI cause the cpu to go into
> startup-ipi-wait or to start booting at 4G-16 bytes.
> 
> For dealing with BIOSen we may still need to use the bootstrap processor
> for firmware calls, cpu suspend, and other firmware weirdness, but that
> should all be completely orthogonal to the behavior to what happens
> when an INIT IPI is sent to the cpu.
> 
> The only firmware problem I can imagine having is cpu virtualization
> bug.
> 

The whole problem is that some BIOSes go wonky after receiving an INIT
(as in INIT-SIPI-SIPI) to the BSP.

	-hpa
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