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From: Borislav Petkov <bp@alien8.de>
To: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: ebiederm@xmission.com, vgoyal@redhat.com,
	akpm@linux-foundation.org, hpa@linux.intel.com,
	kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
	jingbai.ma@hp.com
Subject: Re: [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP
Date: Wed, 4 Sep 2013 08:12:22 +0200	[thread overview]
Message-ID: <20130904061221.GA17791@x1.alien8.de> (raw)
In-Reply-To: <52245D94.5050702@jp.fujitsu.com>

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.

-- 
Regards/Gruss,
Boris.

WARNING: multiple messages have this Message-ID (diff)
From: Borislav Petkov <bp@alien8.de>
To: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: jingbai.ma@hp.com, kexec@lists.infradead.org,
	linux-kernel@vger.kernel.org, ebiederm@xmission.com,
	akpm@linux-foundation.org, hpa@linux.intel.com,
	vgoyal@redhat.com
Subject: Re: [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP
Date: Wed, 4 Sep 2013 08:12:22 +0200	[thread overview]
Message-ID: <20130904061221.GA17791@x1.alien8.de> (raw)
In-Reply-To: <52245D94.5050702@jp.fujitsu.com>

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.

-- 
Regards/Gruss,
Boris.

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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

  reply	other threads:[~2013-09-04  6:12 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-29  9:27 [PATCH 0/2] x86, apic: Disable BSP if boot cpu is AP HATAYAMA Daisuke
2013-08-29  9:27 ` HATAYAMA Daisuke
2013-08-29  9:27 ` [PATCH 1/2] x86, apic: Add boot_cpu_is_bsp() to check if boot cpu is BSP HATAYAMA Daisuke
2013-08-29  9:27   ` HATAYAMA Daisuke
2013-10-09 23:15   ` [tip:x86/bsp-hotplug] " tip-bot for HATAYAMA Daisuke
2013-08-29  9:28 ` [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP HATAYAMA Daisuke
2013-08-29  9:28   ` HATAYAMA Daisuke
2013-08-31  5:22   ` Borislav Petkov
2013-08-31  5:22     ` Borislav Petkov
2013-09-02  2:32     ` HATAYAMA Daisuke
2013-09-02  2:32       ` HATAYAMA Daisuke
2013-09-02  7:13       ` Borislav Petkov
2013-09-02  7:13         ` Borislav Petkov
2013-09-02  9:42         ` HATAYAMA Daisuke
2013-09-02  9:42           ` HATAYAMA Daisuke
2013-09-04  6:12           ` Borislav Petkov [this message]
2013-09-04  6:12             ` Borislav Petkov
2013-09-09  6:18             ` HATAYAMA Daisuke
2013-09-09  6:18               ` HATAYAMA Daisuke
2013-10-09 23:16   ` [tip:x86/bsp-hotplug] " tip-bot for HATAYAMA Daisuke
2013-10-12 17:31     ` H. Peter Anvin
2013-10-12 17:42       ` Ingo Molnar
2013-11-11 19:54         ` H. Peter Anvin
2013-11-12 10:20           ` HATAYAMA Daisuke
2013-11-12 15:35             ` H. Peter Anvin
2013-08-29 13:54 ` [PATCH 0/2] " H. Peter Anvin
2013-08-29 13:54   ` H. Peter Anvin
2013-08-29 23:37   ` Eric W. Biederman
2013-08-29 23:37     ` Eric W. Biederman
2013-08-30 12:48     ` Vivek Goyal
2013-08-30 12:48       ` Vivek Goyal
2013-08-29 23:51   ` HATAYAMA Daisuke
2013-08-29 23:51     ` HATAYAMA Daisuke
2013-08-30 15:43     ` H. Peter Anvin
2013-08-30 15:43       ` H. Peter Anvin
2013-10-09 20:20       ` Vivek Goyal
2013-10-09 20:20         ` Vivek Goyal
2013-10-14  9:03         ` Petr Tesarik
2013-10-14  9:03           ` Petr Tesarik

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