From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752672Ab1HIHlK (ORCPT ); Tue, 9 Aug 2011 03:41:10 -0400 Received: from mga02.intel.com ([134.134.136.20]:2511 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751468Ab1HIHlI (ORCPT ); Tue, 9 Aug 2011 03:41:08 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,342,1309762800"; d="scan'208";a="36675986" Date: Tue, 9 Aug 2011 10:41:41 +0300 From: Mika Westerberg To: Seemanta Dutta Cc: linux-kernel@vger.kernel.org Subject: Re: kdump: Trouble reading /dev/oldmem from capture kernel Message-ID: <20110809074141.GF16790@intel.com> References: <3f4665f1a191945db7c1711ecd154509.squirrel@www.codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3f4665f1a191945db7c1711ecd154509.squirrel@www.codeaurora.org> 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 Fri, Aug 05, 2011 at 02:01:03PM -0700, Seemanta Dutta wrote: > > 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. Is there some specific reason to use /dev/oldmem instead? At least I've never needed that interface. crash utility works pretty well with /dev/vmcore. > 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. I haven't tried lately but it looks like ARM is missing setting of 'saved_max_pfn' which could explain why it works that way.