From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com [209.85.212.177]) by kanga.kvack.org (Postfix) with ESMTP id 03A966B0253 for ; Mon, 12 Oct 2015 06:32:39 -0400 (EDT) Received: by wicge5 with SMTP id ge5so144372884wic.0 for ; Mon, 12 Oct 2015 03:32:38 -0700 (PDT) Received: from mail-wi0-f174.google.com (mail-wi0-f174.google.com. [209.85.212.174]) by mx.google.com with ESMTPS id un4si6277551wjc.206.2015.10.12.03.32.37 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 12 Oct 2015 03:32:37 -0700 (PDT) Received: by wieq12 with SMTP id q12so13405408wie.1 for ; Mon, 12 Oct 2015 03:32:37 -0700 (PDT) Date: Mon, 12 Oct 2015 11:32:35 +0100 From: Matt Fleming Subject: Re: [PATCH][RFC] mm: Introduce kernelcore=reliable option Message-ID: <20151012103235.GB2579@codeblueprint.co.uk> References: <1444402599-15274-1-git-send-email-izumi.taku@jp.fujitsu.com> <561762DC.3080608@huawei.com> <561787DA.4040809@jp.fujitsu.com> <5617989E.9070700@huawei.com> <5617D878.5060903@intel.com> <3908561D78D1C84285E8C5FCA982C28F32B523DB@ORSMSX114.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F32B523DB@ORSMSX114.amr.corp.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Luck, Tony" Cc: "Hansen, Dave" , Xishi Qiu , Kamezawa Hiroyuki , Taku Izumi , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "mel@csn.ul.ie" , "akpm@linux-foundation.org" , Mel Gorman , Ingo Molnar , "zhongjiang@huawei.com" On Fri, 09 Oct, at 06:51:34PM, Luck, Tony wrote: > > Current hardware can map one mirrored region from each memory controller. > We have two memory controllers per socket. So on a 4-socket machine we will > usually have 8 separate mirrored ranges. Two per NUMA node (assuming > cluster on die is not enabled). > > Practically I think it is safe to assume that any sane configuration will always > choose to mirror the <4GB range: > > 1) It's a trivial percentage of total memory on a system that supports mirror > (2GB[1] out of my, essentially minimal, 512GB[2] machine). So 0.4% ... why would > you not mirror it? > 2) It contains a bunch of things that you are likely to want mirrored. Currently > our boot loaders put the kernel there (don't they??). All sorts of BIOS space that > might be accessed at any time by SMI is there. Yeah, the bootloader and kernel image will most likely be in < 4GB region. That's not a hard requirement, and there's certainly support for loading things at higher addresses, but this low region is currently still preferred (see CONFIG_PHYSICAL_START). -- Matt Fleming, Intel Open Source Technology Center -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org