From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Brook Subject: Re: RFC qdev path semantics Date: Thu, 17 Jun 2010 23:01:21 +0100 Message-ID: <201006172301.22115.paul@codesourcery.com> References: <20100614054923.879.33717.stgit@localhost.localdomain> <1276811010.3216.25.camel@x201> Mime-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Markus Armbruster , qemu-devel@nongnu.org, chrisw@redhat.com, kvm@vger.kernel.org, kraxel@redhat.com, avi@redhat.com To: Alex Williamson Return-path: Received: from mail.codesourcery.com ([38.113.113.100]:39024 "EHLO mail.codesourcery.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755136Ab0FQWBc (ORCPT ); Thu, 17 Jun 2010 18:01:32 -0400 In-Reply-To: <1276811010.3216.25.camel@x201> Sender: kvm-owner@vger.kernel.org List-ID: > > ### Paul proposes to require all buses to define bus addresses. Make > > one up if necessary. > > That seems arbitrary and prone to breakage. How do we handle a subtle > change in device instantiation order and still allow migration? If by > code change or command line ordering my frobnitz moves from: > > /i440FX-pcihost/pci.0/PIIX3/@01.0/isa.0/0 > > to > > /i440FX-pcihost/pci.0/PIIX3/@01.0/isa.0/1 Two things are apparent here. (a) You've clearly misunderstood the proposals. The paths above make no sense. (b) You've picked a particularly poor definition of device address for the ISA bus. We can do much better than device creation order. > ... > I can live with PATH/@BUS-ADDR if it's still felt that > PATH/IDENT@BUS-ADDR isn't canonical. What that means is that I'll > probably code up vmstate and ramblocks to append IDENT themselves to > keep all the goodness of having per PATH/IDENT namespaces. As discussed elsewhere in this thread, addition of IDENT to the device path is neither necessary nor sufficient for migration. I really feel like we're going round in circles here. Paul