linux-kernel - Re: [tip:x86/urgent] x86, apic: Map the local apic when parsing the MP table.

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Message-ID: <m1fwyrgmsf.fsf@fess.ebiederm.org>
Date:	Fri, 06 Aug 2010 19:49:04 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>, mingo@...hat.com,
	linux-kernel@...r.kernel.org, tvrtko.ursulin@...hos.com,
	hilld@...arystorm.net, tglx@...utronix.de, hpa@...ux.intel.com,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86, apic: Map the local apic when parsing the MP table.

Yinghai Lu <yinghai@...nel.org> writes:

> On 08/06/2010 06:21 PM, H. Peter Anvin wrote:
>> On 08/06/2010 06:08 PM, Eric W. Biederman wrote:
>>>>
>>>> I'm not sure the above is decipherable.  Please provide an incremental
>>>> patch with a more detailed description.
>>>
>>> YH was saying I overoptimized, and it looks like he is right,
>>> although there are only one or two machines in existence that
>>> are likely to be affected.
>>>
>>> Untested patch to remove the cleverness below.  It it boots all
>>> is well.
>>>
>> 
>> This makes sense to me.  Yinghai, do you have a system that is actually
>> affected, and if so, could you test this patch?
>
> no, i don't have those kind of system.

I don't know if anyone does.  It looks like sfi aka moorestown
and visws are what are affected.

That is why I made a patch that any boot where we exercise a local
apic will exercise.

Arguably if it is best to just remove that hunk from my patch, so
we have something that is safe to backport to 2.6.35.1.

> found it when i was preparing more smp_register_lapic_address patcheset.
>
> I suggest we still keep !acpi_lapic checking, that should always right.

Ultimately we want to remove the code duplication entirely.

Eric
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