From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754296Ab3AVPz0 (ORCPT ); Tue, 22 Jan 2013 10:55:26 -0500 Received: from terminus.zytor.com ([198.137.202.10]:34429 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753248Ab3AVPzZ (ORCPT ); Tue, 22 Jan 2013 10:55:25 -0500 Message-ID: <50FEB620.3020805@zytor.com> Date: Tue, 22 Jan 2013 09:54:08 -0600 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Thomas Renninger CC: yinghai@kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, vgoyal@redhat.com, horms@verge.net.au Subject: Re: [PATCH 2/2] x86 e820: Introduce memmap=resetusablemap for kdump usage References: <1358868049-19884-1-git-send-email-trenn@suse.de> <1358868049-19884-3-git-send-email-trenn@suse.de> In-Reply-To: <1358868049-19884-3-git-send-email-trenn@suse.de> X-Enigmail-Version: 1.5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/22/2013 09:20 AM, Thomas Renninger wrote: > From: Yinghai Lu > > kdump voided the whole original e820 map and half way made > it up via memmap= options passed via kdump boot params again. > > But this is conceptionally wrong. The whole original memory ranges > which are declared reserved, ACPI data/nvs or however are not usable > must stay the same and get honored by the kdump kernel. > > Therefore memmap=resetusablemap gets introduced. > kdump passes this one and only the usable e820 ranges are removed. > kdump passes the usable ranges to use via memmap=x@y parameter(s). > The not usable e820 ranges are preserved. > > This for example fixes mmconf (extended PCI config access) and > possibly other kernel parts which rely on remapped memory to be > in reserved or ACPI (data/nvs) declared e820 memory areas. > > Tested-by: Thomas Renninger > Reviewed-by: Thomas Renninger > Signed-off-by: Thomas Renninger Tested-by: and Reviewed-by: are rather redundant with Signed-off-by:. Also, you should have a Signed-off-by: from the author (Yinghai). However, when thinking about it this really doesn't seem to be the right interface, either. Something like "memmap=reserveram" which turns all RAM areas into reserved areas, which can then be overridden by memmap= options would make more sense. Even more sense would be to pass the modified memmap to kexec... -hpa