From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753458Ab2LXXem (ORCPT ); Mon, 24 Dec 2012 18:34:42 -0500 Received: from terminus.zytor.com ([198.137.202.10]:34701 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753377Ab2LXXek (ORCPT ); Mon, 24 Dec 2012 18:34:40 -0500 Message-ID: <50D8E671.3020502@zytor.com> Date: Mon, 24 Dec 2012 15:34:09 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Yinghai Lu CC: "Eric W. Biederman" , Konrad Rzeszutek Wilk , Thomas Gleixner , Ingo Molnar , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 24/27] x86: Add swiotlb force off support References: <1355814959-10573-1-git-send-email-yinghai@kernel.org> <1355814959-10573-25-git-send-email-yinghai@kernel.org> <20121222023741.GF3468@phenom.dumpdata.com> <87bodmhkns.fsf@xmission.com> <20121222031019.GA4120@phenom.dumpdata.com> <87pq22g488.fsf@xmission.com> <50D52841.9030301@zytor.com> In-Reply-To: X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/21/2012 09:11 PM, Yinghai Lu wrote: > On Fri, Dec 21, 2012 at 7:25 PM, H. Peter Anvin wrote: >> On 12/21/2012 07:23 PM, Eric W. Biederman wrote: >>> >>> In this case YH has been working on the case of loading a kernel >>> completely above 4G, and apparently he has also been testing the case of >>> running a kernel with no memory below 4G. >>> >> >> It is worth noting that we cannot run with *no* memory below 4G -- it is >> not possible to run SMP at least without some memory below the 1M mark. > > yes need keep 8k or so for trampoline. > > but kdump only use one CPU. > ... except we have an active request to change that, and the trampoline is more like 20K depending on options. -hpa