Bug 1388177

Summary: virt-manager should default to the ich9 audio device for Q35
Product: [Community] Virtualization Tools Reporter: Laine Stump <laine>
Component: virt-managerAssignee: Cole Robinson <crobinso>
Status: CLOSED UPSTREAM QA Contact:
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Version: unspecifiedCC: berrange, crobinso, gscrivan, jyundt
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Last Closed: 2018-08-29 23:07:20 UTC Type: Bug
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Description Laine Stump 2016-10-24 16:30:15 UTC 
When creating a guest with the Q35 machinetype, virt-manager leaves the default audio device at "ich6". In the real world, the Q35 chipset is paired with an ICH9 controller chip, which includes ich9 audio, and a recent patch to libvirt (ACKed but not yet pushed):

  https://www.redhat.com/archives/libvir-list/2016-October/msg00723.html

takes advantage of this by placing an ich9 audio device at address 00:1B.0 when possible - this means the guest can have an audio device without needing to add any legacy PCI buses (all emulated audio devices in qemu are currently legacy-PCI devices, and libvirt normally prefer to put those on legacy-PCI buses, but is making an exception for ich9 audio (similar to the exceptions for video devices and USB2 controllers) because that is the way it is on real hardware).

Since the audio device is the only device in a "normal" guest config that isn't virtio, and virtio devices will all be assigned to pcie-root-ports as soon as this series is pushed:

  https://www.redhat.com/archives/libvir-list/2016-October/msg00699.html

using an audio device that gets assigned to bus 0 (pcie-root) will make virt-manager created guests completely free of legacy-PCI devices and controllers.
Comment 1 Cole Robinson 2018-08-29 23:07:20 UTC 
Fixed upstream now:

commit 2da06fec957fd9925905ef5c07770622abab4e90
Author: Cole Robinson <crobinso>
Date:   Tue Aug 21 16:11:50 2018 -0400

    guest: Default to ich9 if machine=q35 (bz 1388177)
    
    It's the pci-e version which we should prefer for q35
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1388177