From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753879AbaKMIan (ORCPT ); Thu, 13 Nov 2014 03:30:43 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:36714 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753088AbaKMIam (ORCPT ); Thu, 13 Nov 2014 03:30:42 -0500 X-SecurityPolicyCheck: OK by SHieldMailChecker v2.2.3 X-SHieldMailCheckerPolicyVersion: FJ-ISEC-20140219-2 Message-ID: <54646C1D.1050102@jp.fujitsu.com> Date: Thu, 13 Nov 2014 17:30:21 +0900 From: "HATAYAMA, Daisuke" User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Petr Tesarik CC: vgoyal@redhat.com, kumagai-atsushi@mxc.nes.nec.co.jp, anderson@redhat.com, kexec@lists.infradead.org, ebiederm@xmission.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kdump, x86: report actual value of phys_base in VMCOREINFO References: <20141112.154042.59640143160036130.d.hatayama@jp.fujitsu.com> <20141112221205.GB5265@redhat.com> <20141113.091709.520211949477822929.d.hatayama@jp.fujitsu.com> <20141113090657.2578f087@hananiah.suse.cz> In-Reply-To: <20141113090657.2578f087@hananiah.suse.cz> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/11/13 17:06), Petr Tesarik wrote: > On Thu, 13 Nov 2014 09:17:09 +0900 (JST) > HATAYAMA Daisuke wrote: > >> From: Vivek Goyal >> Subject: Re: [PATCH] kdump, x86: report actual value of phys_base in VMCOREINFO >> Date: Wed, 12 Nov 2014 17:12:05 -0500 >> >>> On Wed, Nov 12, 2014 at 03:40:42PM +0900, HATAYAMA Daisuke wrote: >>>> Currently, VMCOREINFO note information reports the virtual address of >>>> phys_base that is assigned to symbol phys_base. But this doesn't make >>>> sense because to refer to value of the phys_base, it's necessary to >>>> get the value of phys_base itself we are now about to refer to. >>>> >>> >>> Hi Hatayama, >>> >>> /proc/vmcore ELF headers have virtual address information and using >>> that you should be able to read actual value of phys_base. gdb deals >>> with virtual addresses all the time and can read value of any symbol >>> using those headers. >>> >>> So I am not sure what's the need for exporting actual value of >>> phys_base. >>> >> >> Sorry, my logic in the patch description was wrong. For /proc/vmcore, >> there's enough information for makedumpdile to get phys_base. It's >> correct. The problem here is that other crash dump mechanisms that run >> outside Linux kernel independently don't have information to get >> phys_base. > > Yes, but these mechanisms won't be able to read VMCOREINFO either, will > they? > I don't intend such sophisticated function only by VMCOREINFO. Search vmcore for VMCOREINFO using strings + grep before opening it by crash. I intend that only here. -- Thanks. HATAYAMA, Daisuke