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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.39, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "Michael S . Tsirkin" , Jason Wang , qemu-devel@nongnu.org, Markus Armbruster , Eric Auger , Alex Williamson , Paolo Bonzini , Igor Mammedov , "Dr . David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi, Dan, On Thu, Sep 02, 2021 at 02:53:00PM +0100, Daniel P. Berrangé wrote: > The correct ordering of devices/backends is generally pretty obvious > for libvirt to determine. Most of the problems we've had related to > ordering are on the QEMU side, because the ARGV given to QEMU made > correct sense if parsed left-to-right, but QEMU didn't actually process > them in that order. We've patched QEMU to hack around its inability to > honour the CLI order repeatedly. Is there a pointer to the problem? > > Being completely self-ordering on the QEMU side using a topological > sort would be neat from a conceptual purity POV, but that is quite a > challenge to implement and I'm not convinced it is worth it, compared > to other problems we want to spend time on. I just noticed there can also be dependency between the buses; that cannot be fixed by ordering of classes indeed as either proposed in this series, or introduce a new priority. Thanks, -- Peter Xu