Re: [PATCH v1 2/2] x86, apic: Disable BSP if boot cpu is AP
From: H. Peter Anvin
Date: Mon Oct 22 2012 - 16:39:14 EST
On 10/22/2012 01:33 PM, H. Peter Anvin wrote:
> 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
> The whole problem is that some BIOSes go wonky after receiving an INIT
> (as in INIT-SIPI-SIPI) to the BSP.
(I presume the failure is SMM-related, but Fenghua might have more
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