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Message-ID: <5085AD7D.106@zytor.com>
Date: Mon, 22 Oct 2012 13:33:01 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
CC: HATAYAMA Daisuke <d.hatayama@...fujitsu.com>,
linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
x86@...nel.org, mingo@...e.hu, tglx@...utronix.de,
len.brown@...el.com, fenghua.yu@...el.com, vgoyal@...hat.com,
grant.likely@...retlab.ca, rob.herring@...xeda.com
Subject: Re: [PATCH v1 2/2] x86, apic: Disable BSP if boot cpu is AP
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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