From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx181.postini.com [74.125.245.181]) by kanga.kvack.org (Postfix) with SMTP id 05ABC6B00A2 for ; Tue, 29 Jan 2013 13:38:05 -0500 (EST) From: "Luck, Tony" Subject: RE: [PATCH 3/3] acpi, memory-hotplug: Support getting hotplug info from SRAT. Date: Tue, 29 Jan 2013 18:38:03 +0000 Message-ID: <3908561D78D1C84285E8C5FCA982C28F1C9909DD@ORSMSX108.amr.corp.intel.com> References: <1359106929-3034-1-git-send-email-tangchen@cn.fujitsu.com> <1359106929-3034-4-git-send-email-tangchen@cn.fujitsu.com> <20130125171230.34c5a273.akpm@linux-foundation.org> <51033186.3000706@zytor.com> <5105DD4B.9020901@cn.fujitsu.com> <3908561D78D1C84285E8C5FCA982C28F1C98F9CB@ORSMSX108.amr.corp.intel.com> <51076FAC.9060605@cn.fujitsu.com> In-Reply-To: <51076FAC.9060605@cn.fujitsu.com> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Tang Chen Cc: "H. Peter Anvin" , Andrew Morton , "jiang.liu@huawei.com" , "wujianguo@huawei.com" , "wency@cn.fujitsu.com" , "laijs@cn.fujitsu.com" , "linfeng@cn.fujitsu.com" , "yinghai@kernel.org" , "isimatu.yasuaki@jp.fujitsu.com" , "rob@landley.net" , "kosaki.motohiro@jp.fujitsu.com" , "minchan.kim@gmail.com" , "mgorman@suse.de" , "rientjes@google.com" , "guz.fnst@cn.fujitsu.com" , "rusty@rustcorp.com.au" , "lliubbo@gmail.com" , "jaegeuk.hanse@gmail.com" , "glommer@parallels.com" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" >> Node 0 (or more specifically the node that contains memory<4GB) will be >> full of BIOS reserved holes in the memory map. > One thing I'm not sure, is memory<4GB always on node 0 ? > On my box, it is on node 0. I think in practice the <4GB memory will be on node 0 ... but it all depend= s on how Linux decides to number the nodes ... which in turn depends on the order of entries in various BIOS tables. So it is theoretically possible t= hat we'd end up with some system on which the low memory is on some other node. But it might require stranger than usual BIOS. Summary: coding "node =3D=3D 0" is almost 100% certain to be right - except on some pathological systems. So code for node=3D=3D0 and if we ever see a pathological machine - we can either point and laugh at the BIOS people that set that up - or possibly fix our code. -Tony -- 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