From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [PATCH 1/6] virtio interace Date: Sun, 23 Sep 2007 18:33:51 +1000 Message-ID: <1190536431.27805.109.camel@localhost.localdomain> References: <1190289808.7262.223.camel@localhost.localdomain> <200709211622.22005.arnd@arndb.de> <1190454934.27805.80.camel@localhost.localdomain> <200709221201.33865.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , lguest , virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Arnd Bergmann Return-path: In-Reply-To: <200709221201.33865.arnd-r2nGTMty4D4@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org On Sat, 2007-09-22 at 12:01 +0200, Arnd Bergmann wrote: > On Saturday 22 September 2007, Rusty Russell wrote: > > But now each virtio device has two "struct device"s, not one. And > > you've made up a fictional bus to do it. > > > > Yet for PCI systems, it really is a PCI device; exposing a second bus to > > userspace just because we put a layer in our implementation is poor > > form. > > > > Perhaps this is the easiest way of doing it. But it's still wrong. > > I think it's just a matter of perspective. In the model I'm advocating, > the PCI device is not the same as the virtio device but rather a virtio > host bridge, very much like USB or SATA works. > > We could easily have multiple virtio devices behind one PCI device, but > since virtual PCI devices are cheap, a one-to-one mapping makes sense > for simplicity. This is still retro-justification. The simplest way for PCI systems to represent a virtio device as a PCI device; this makes life easy for any guest OS. I just know we're going to regret this... Rusty. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/