From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f179.google.com (mail-pd0-f179.google.com [209.85.192.179]) by kanga.kvack.org (Postfix) with ESMTP id C43CE6B0031 for ; Mon, 13 Jan 2014 20:15:08 -0500 (EST) Received: by mail-pd0-f179.google.com with SMTP id y10so1150211pdj.38 for ; Mon, 13 Jan 2014 17:15:08 -0800 (PST) Received: from g1t0027.austin.hp.com (g1t0027.austin.hp.com. [15.216.28.34]) by mx.google.com with ESMTPS id sa6si17211452pbb.323.2014.01.13.17.15.06 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 13 Jan 2014 17:15:07 -0800 (PST) Message-ID: <1389661746.1792.254.camel@misato.fc.hp.com> Subject: Re: [PATCH 2/2] x86, e820 disable ACPI Memory Hotplug if memory mapping is specified by user [v2] From: Toshi Kani Date: Mon, 13 Jan 2014 18:09:06 -0700 In-Reply-To: <52D48A9D.7000003@zytor.com> References: <1389380698-19361-1-git-send-email-prarit@redhat.com> <1389380698-19361-4-git-send-email-prarit@redhat.com> <52D32962.5050908@redhat.com> <52D4793E.8070102@redhat.com> <1389659632.1792.247.camel@misato.fc.hp.com> <52D48A9D.7000003@zytor.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "H. Peter Anvin" Cc: Prarit Bhargava , KOSAKI Motohiro , Bodo Eggert <7eggert@gmx.de>, LKML , Thomas Gleixner , Ingo Molnar , the arch/x86 maintainers , Len Brown , "Rafael J. Wysocki" , Linn Crosetto , Pekka Enberg , Yinghai Lu , Andrew Morton , Tang Chen , Wen Congyang , Vivek Goyal , dyoung@redhat.com, linux-acpi@vger.kernel.org, "linux-mm@kvack.org" On Mon, 2014-01-13 at 16:53 -0800, H. Peter Anvin wrote: > On 01/13/2014 04:33 PM, Toshi Kani wrote: > > > > I do not think it makes sense. You needed memmap=exactmap as a > > workaround because the kernel did not boot with the firmware's memory > > info. So, it's broken, and you requested the kernel to ignore the > > firmware info. > > > > Why do you think memory hotplug needs to be supported under such > > condition, which has to use the broken firmware info? > > > > Even more than memory hotplug: what do we do with NUMA? Since we have > already told the kernel "the firmware is bogus" it would seem that any > NUMA optimizations would be a bit ... cantankerous at best, no? Agreed that NUMA info can be bogus in this case, but is probably not critical. In majority of the cases, memmap=exactmap is used for kdump and the firmware info is sane. So, I think we should keep NUMA enabled since it could be useful when multiple CPUs are enabled for kdump. Thanks, -Toshi -- 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