From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752565AbXJVNxt (ORCPT ); Mon, 22 Oct 2007 09:53:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751304AbXJVNxl (ORCPT ); Mon, 22 Oct 2007 09:53:41 -0400 Received: from ns1.suse.de ([195.135.220.2]:45563 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751102AbXJVNxk (ORCPT ); Mon, 22 Oct 2007 09:53:40 -0400 To: Or Sagi Cc: linux-kernel , Nir Peleg Subject: Re: [PATCH] Reserve low memory From: Andi Kleen References: <20071021165401.GA8626@cleopatra.qumranet.com> Date: Mon, 22 Oct 2007 15:53:39 +0200 In-Reply-To: <20071021165401.GA8626@cleopatra.qumranet.com> (Or Sagi's message of "Sun\, 21 Oct 2007 18\:54\:01 +0200") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Or Sagi writes: > Adds a CONFIG_RESERVE_LOWMEM option which reserves all memory below > CONFIG_PHYSICAL_START address. > > Cleans up some of the static early-boot memory allocations (nodemap, trampoline) > Useful in particular for running virtual machines which require a 1:1 mapping > of the physical memory. This lets a virtual machine control a dma-capable device > directly without hypervisor involvement. With the infrastructure in ftp://firstfloor.org/pub/ak/x86_64/quilt/patches/early-reserve you can do this much cleaner (and likely safer) And using CONFIG_* options for such things is wrong anyways. If anything it should be run time options. -Andi >