From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755891Ab1HEVBU (ORCPT ); Fri, 5 Aug 2011 17:01:20 -0400 Received: from wolverine02.qualcomm.com ([199.106.114.251]:53334 "EHLO wolverine02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752112Ab1HEVBH (ORCPT ); Fri, 5 Aug 2011 17:01:07 -0400 X-IronPort-AV: E=McAfee;i="5400,1158,6429"; a="108261127" Message-ID: <3f4665f1a191945db7c1711ecd154509.squirrel@www.codeaurora.org> Date: Fri, 5 Aug 2011 14:01:03 -0700 (PDT) Subject: kdump: Trouble reading /dev/oldmem from capture kernel From: "Seemanta Dutta" To: linux-kernel@vger.kernel.org User-Agent: SquirrelMail/1.4.17 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Priority: 3 (Normal) Importance: Normal Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Greetings kernel hackers, I am trying to dump the raw memory from the /dev/oldmem device from within a kexec()'ed capture kernel. But it seems to be that I can only read 4k of data from /dev/oldmem. I am following the kdump documentation given in: http://www.mjmwired.net/kernel/Documentation/kdump/. And according to the documentation in the above link, /dev/oldmem *should* present the raw view of memory. Some details about my scenario: 1. Production kernel panics, and I boot into the dump capture kernel without any issues. 2. Dump capture kernel provides two interfaces to access 'old' kernel memory (as per kdump dpcumentation): /dev/oldmem and /proc/vmcore. The latter works perfectly. But I am more interested in the raw memory, rather than the core file. My expectation in this scenario was that I would be able to access entire physical RAM using the /dev/oldmem device. But turns out, I can't. I would be grateful if anyone pointed out if I was doing something wrong or missing something. This is happening over ARM. Could that have to do something with this ? Not sure if the ARM integration of KDUMP/KEXEC has something to do with it. Your help would be greatly appreciated! regards, Seemanta -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum