From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422672AbXDCUDy (ORCPT ); Tue, 3 Apr 2007 16:03:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422671AbXDCUDy (ORCPT ); Tue, 3 Apr 2007 16:03:54 -0400 Received: from terminus.zytor.com ([192.83.249.54]:45746 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422672AbXDCUDx (ORCPT ); Tue, 3 Apr 2007 16:03:53 -0400 Message-ID: <4612B303.5000109@zytor.com> Date: Tue, 03 Apr 2007 13:03:15 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 1.5.0.9 (X11/20070212) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: Arnd Bergmann , Cornelia Huck , Andi Kleen , Christian Borntraeger , virtualization@lists.linux-foundation.org, Virtualization Mailing List , Linux Kernel Mailing List , mathiasen@gmail.com Subject: Re: A set of "standard" virtual devices? References: <4611652F.700@zytor.com> <200704031951.00544.arnd@arndb.de> <4612A5F0.2080609@goop.org> <200704032142.51976.arnd@arndb.de> <4612B123.2040105@goop.org> In-Reply-To: <4612B123.2040105@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: > > Yes, and that's the core of the Xen netfront. But is there really much > code which can be shared between different hypervisors? When you get > down to it, all the real code is hypervisor-specific stuff for setting > up ringbuffers and dealing with interrupts. Like all the other network > drivers. > One thing, Jeremy, which I think is being a bit misleading here: you're focusing on big, performance-critical stuff. Those things are going to be the ones which has the most win to implement in hypervisor-specific ways. Although we can offer models for some hypervisors (and G-d knows there are enough implementations out there of virtual disk which are almost identical), they're clearly not going to be universal. However, there are other things; console is some, or my original example, which was random number generation. For those, the benefit of unification is proportionally greater, simply because the win of anything hypervisor-specific is much smaller. -hpa