From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from terminus.zytor.com ([2001:1868:205::10] helo=mail.zytor.com) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TxgB8-00044D-VQ for kexec@lists.infradead.org; Tue, 22 Jan 2013 15:54:27 +0000 Message-ID: <50FEB620.3020805@zytor.com> Date: Tue, 22 Jan 2013 09:54:08 -0600 From: "H. Peter Anvin" MIME-Version: 1.0 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> 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-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Thomas Renninger Cc: x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, horms@verge.net.au, yinghai@kernel.org, vgoyal@redhat.com 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 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec