linux-kernel - Re: [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP

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Date:	Mon, 09 Sep 2013 15:18:06 +0900
From:	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	jingbai.ma@...com, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org, ebiederm@...ssion.com,
	akpm@...ux-foundation.org, hpa@...ux.intel.com, vgoyal@...hat.com
Subject: Re: [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP

(2013/09/04 15:12), Borislav Petkov wrote:
> On Mon, Sep 02, 2013 at 06:42:44PM +0900, HATAYAMA Daisuke wrote:
>> The reason why I don't lookup BSP flag in MSR is that it's impossible.
>> To read MSR of some CPU, we need to use rdmsr instruction on the CPU.
>> However, in case of this issue, the BSP is halting or running in
>> the kdump 1st kernel.
>
> Yes, and on the AP, that flag would be cleared which makes it not a BSP.
>
>> A whole explanation is written in the patch description.
>
> Those tend to get lost in git history when a bunch of whitespace jerk
> offs appear ontop. So a nicely written comment in the code could be very
> helpful.
>
> Thanks.
>

Yes, that's the point this patch series misses. I'll describe the explanation
in Documentation/kexec/kexec.txt and point it in the comment of boot-up code.

-- 
Thanks.
HATAYAMA, Daisuke

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