From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W1TFH-00080t-5J for kexec@lists.infradead.org; Fri, 10 Jan 2014 03:58:56 +0000 Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 389093EE0C0 for ; Fri, 10 Jan 2014 12:58:28 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 2190145DEBE for ; Fri, 10 Jan 2014 12:58:28 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.nic.fujitsu.com [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id F251E45DD77 for ; Fri, 10 Jan 2014 12:58:27 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id E5DA41DB803B for ; Fri, 10 Jan 2014 12:58:27 +0900 (JST) Received: from g01jpfmpwyt02.exch.g01.fujitsu.local (g01jpfmpwyt02.exch.g01.fujitsu.local [10.128.193.56]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 7CFD81DB803F for ; Fri, 10 Jan 2014 12:58:27 +0900 (JST) Message-ID: <52CF6FBE.8000005@jp.fujitsu.com> Date: Fri, 10 Jan 2014 12:57:50 +0900 From: Yasuaki Ishimatsu MIME-Version: 1.0 Subject: Re: [PATCH] acpi memory hotplug, add parameter to disable memory hotplug for kexec References: <1389220181-14474-1-git-send-email-prarit@redhat.com> <3476878.EqQiEtA2Ag@vostro.rjw.lan> <20140109150053.GD25897@redhat.com> <20140109214425.GD12111@redhat.com> In-Reply-To: <20140109214425.GD12111@redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: Vivek Goyal , Prarit Bhargava Cc: Kexec Mailing List , "Rafael J. Wysocki" , linux kernel mailing list , linux-acpi@vger.kernel.org, KOSAKI Motohiro , Dave Young , Len Brown (2014/01/10 6:44), Vivek Goyal wrote: > On Thu, Jan 09, 2014 at 04:34:16PM -0500, KOSAKI Motohiro wrote: >> On Thu, Jan 9, 2014 at 10:00 AM, Vivek Goyal wrote: >>> On Thu, Jan 09, 2014 at 12:00:29AM +0100, Rafael J. Wysocki wrote: >>> >>> [..] >>>>> The system then panics and the kdump/kexec kernel boots. During this boot >>>>> ACPi is initialized and the kernel (as can be seen above) >>>> >>>> Which is a bug. You're not supposed to initialize ACPI twice in a row. >>> >>> [CC lkml, kexec mailing list, dave young] >>> >>> It is a fresh instance of kernel booting and it is initializing its data >>> structures fresh. It is *not* re-initializing ACPI in same kernel. >>> >>>>> This patchset resolves the problem by adding a kernel parameter, >>>>> no_memory_hotplug, to disable ACPI memory hotplug. It can be added by default >>>>> as a parameter to the kexec/kdump kernel so the kernel boots correctly. >>>> >>>> This problem is specific to kexec/kdump, so please don't add *generic* command >>>> line parameters to address this. >>>> >>> >>> There are other command line options to solve kdump problems. In general >>> one might want to disable memory hogplug on the fly even if it is compiled >>> in the kernel. So it can act as a good debugging aid. >>> >>> Secondly, it can be specified with memmap=exactmap and mem=X paramters to >>> make sure no memory is hot added in the system. >>> >>> So I can see other usages of this parameter. To me it makes sense to have >>> a separate command line option to disable memory hotplug feature on the >>> fly. >> >> I'm ok this option. But note, even if this option is specified, SH, >> Power and S390 still >> be able to use memory hotplug because their firmware are totally >> different from ACPI. >> >> Maybe, adding acpi prefix provides good clarification. > > Makes sense. Something like "acpi_no_memhotplug" or "acpi_disable_memhotplug" > or something else. I like Prarit's patch and the boot option name. If it is updated, I'll test it. Thanks, Yasuaki Ishimatsu > > Thanks > Vivek > > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec