Re: [Qemu-devel] [PATCH V3] hw/virtio: Add PCIe capability to virtio devices

[Marcel Apfelbaum <marcel@redhat.com>]

On 11/02/2015 02:05 PM, Cornelia Huck wrote:
> On Mon, 2 Nov 2015 12:01:06 +0200
> Marcel Apfelbaum <marcel@redhat.com> wrote:
>
>> On 11/02/2015 11:54 AM, Cornelia Huck wrote:
>>> On Mon, 2 Nov 2015 11:20:50 +0200
>>> Marcel Apfelbaum <marcel@redhat.com> wrote:
>>>
>>>> On 11/02/2015 11:07 AM, Cornelia Huck wrote:
>>>>> On Sun, 1 Nov 2015 11:15:24 +0200
>>>>> Marcel Apfelbaum <marcel@redhat.com> wrote:
>>>>>
>>>>>> By the way, HW_COMPAT_2_3 sets any-layout to off only for a few virtio devices,
>>>>>> not for all. Does anybody know if is in purpose or can we do the same for them too?
>>>>>
>>>>> net and scsi already defaulted any_layout to true before.
>>>>>
>>>>> Are any others missing?
>>>>>
>>>>
>>>> Hi,
>>>>
>>>> The whole list is:
>>>>     name "virtio-blk-pci", bus PCI, alias "virtio-blk"
>>>>     name "virtio-scsi-pci", bus PCI
>>>>     name "virtio-net-pci", bus PCI, alias "virtio-net"
>>>>     name "virtio-input-host-pci", bus PCI
>>>>     name "virtio-keyboard-pci", bus PCI
>>>>     name "virtio-mouse-pci", bus PCI
>>>>     name "virtio-serial-pci", bus PCI, alias "virtio-serial"
>>>>     name "virtio-tablet-pci", bus PCI
>>>>     name "virtio-gpu-pci", bus PCI
>>>>     name "virtio-balloon-pci", bus PCI, alias "virtio-balloon"
>>>>     name "virtio-rng-pci", bus PCI
>>>>
>>>>
>>>> HW_COMPAT_2_3 has:
>>>>      - virtio-blk-pci
>>>>      - virtio-balloon-pci
>>>>      - virtio-serial-pci
>>>>      - virtio-9p-pci
>>>>      - virtio-rng-pci
>>>>
>>>> You mentioned:
>>>>      - virtio-scsi-pci
>>>>      - virtio-net-pci
>>>>
>>>> I guess the remaining list is:
>>>>     - virtio-input-host-pci
>>>>     - virtio-keyboard-pci
>>>>     - virtio-mouse-pci
>>>>     - virtio-tablet-pci
>>>>     - virtio-gpu-pci
>>>>
>>>> I don't know if is is applicable to them, or if they have it defaulted to any_layout,
>>>> however the above devices are part of QEMU 2.3.
>>>
>>> Hm, unless I'm fumbling git commands here, they were all added post-2.3?
>>
>> I misspoke, I wanted to say that when I run (latest master branch):
>>    <qemu-bin>  -M pc-q35-2.3  -device help 2>&1 | grep virtio | grep pci
>> the devices are there.
>
> What's the word on compat machines and new device types, btw.? If we
> fire up a compat machine, we can still specify devices that were added
> with later machine versions, but of course we can't migrate to an old
> machine as the device types did not exist there. Do we want to give the
> user a hint here by disallowing new device types?
>

I started to wonder about this too, so I added to this thread the migration
maintainers that should be qualified to answer this :)

Thanks,
Marcel