From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932067AbXBMX6W (ORCPT ); Tue, 13 Feb 2007 18:58:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932070AbXBMX6W (ORCPT ); Tue, 13 Feb 2007 18:58:22 -0500 Received: from smtp-outbound-1.vmware.com ([65.113.40.141]:53564 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932067AbXBMX6V (ORCPT ); Tue, 13 Feb 2007 18:58:21 -0500 Message-ID: <45D2509C.4070502@vmware.com> Date: Tue, 13 Feb 2007 15:58:20 -0800 From: Zachary Amsden User-Agent: Thunderbird 1.5.0.9 (X11/20061206) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: Dan Hecht , Andrew Morton , xen-devel@lists.xensource.com, Ian Pratt , linux-kernel@vger.kernel.org, Chris Wright , Andi Kleen , virtualization@lists.osdl.org Subject: Re: [Xen-devel] Re: [patch 14/21] Xen-paravirt: Add XEN config options and disable unsupported config options. References: <20070213221729.772002682@goop.org> <20070213221830.542511707@goop.org> <45D24172.9020800@vmware.com> <45D249D9.80407@goop.org> In-Reply-To: <45D249D9.80407@goop.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jeremy Fitzhardinge wrote: > Dan Hecht wrote: > >> I assume you plan to eventually get all this stuff working but just >> want to prevent configurations that the Xen paravirt-ops isn't ready >> for at the moment? >> >> Instead can you do it this way: >> >> config XEN >> depends on PARAVIRT && !PREEMPT && HZ_100 && !DOUBLEFAULT && !KEXEC >> > > That's a bit simpler code-wise, but it does make it pretty complex to > get everything just-so to even see the CONFIG_XEN option. > Yes, but that is what you need to do to compile Xen - logically, to build a Xen kernel, you need to have a kernel configuration which can enable Xen - not limit the configuration of a kernel because Xen has been enabled. This is because with paravirt-ops, Xen compiled kernels may not actually run on Xen, so you can't arbitrarily drop features because you assume Xen is there. One of these has an easy solution - doublefault. You don't need to install the doublefault gate if you don't want it, and the hypervisor doesn't need to freak out if you install it, it can just ignore the gate entirely and claim #DF is not supported. Zach