From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756505Ab3IDGMA (ORCPT ); Wed, 4 Sep 2013 02:12:00 -0400 Received: from mail.skyhub.de ([78.46.96.112]:43809 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752458Ab3IDGL6 (ORCPT ); Wed, 4 Sep 2013 02:11:58 -0400 Date: Wed, 4 Sep 2013 08:12:22 +0200 From: Borislav Petkov To: HATAYAMA Daisuke 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 Message-ID: <20130904061221.GA17791@x1.alien8.de> References: <20130829092458.5476.10277.stgit@localhost6.localdomain6> <20130829092804.5476.95588.stgit@localhost6.localdomain6> <20130831052252.GC12617@x1.alien8.de> <5223F8DB.3040506@jp.fujitsu.com> <20130902071318.GA3406@x1.alien8.de> <52245D94.5050702@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <52245D94.5050702@jp.fujitsu.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.skyhub.de ([2a01:4f8:120:8448::d00d]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VH6KI-00041K-6O for kexec@lists.infradead.org; Wed, 04 Sep 2013 06:12:27 +0000 Date: Wed, 4 Sep 2013 08:12:22 +0200 From: Borislav Petkov Subject: Re: [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP Message-ID: <20130904061221.GA17791@x1.alien8.de> References: <20130829092458.5476.10277.stgit@localhost6.localdomain6> <20130829092804.5476.95588.stgit@localhost6.localdomain6> <20130831052252.GC12617@x1.alien8.de> <5223F8DB.3040506@jp.fujitsu.com> <20130902071318.GA3406@x1.alien8.de> <52245D94.5050702@jp.fujitsu.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <52245D94.5050702@jp.fujitsu.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: HATAYAMA Daisuke 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 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. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec