Re: [Qemu-devel] [PATCH V2] hw/virtio-pci: fix virtio behaviour on modern (PCIe) machines

[Marcel Apfelbaum <marcel@redhat.com>]

On 07/20/2016 11:41 AM, Gerd Hoffmann wrote:
>>> Notes:
>>>     - The non PCIe machines behaviour should remain the same.
>>>     - I hope is OK to make the disable-* properties OnOffAuto. Previous setups
>>>       using them can be affected,
>>
>> why? could you explain pls? isn't onoffauto compatible with bit
>> properties?
>
> I have the same question ;)
>

Hi Gerd,

As I explained to Michael, I saw the 'off' value goes from 0 to 2, bu the name remains the same... :)
I wasn't sure if is possible to use 0/1 instead of on/off, then we would have a problem.

>> Also, I wonder how does this interact with devices that play with
>> these flags themselves, like virtio gpu?
>
> virtio input forces virtio 1.0 only too.
> I think they must be changed to set the new property variables instead.
>

I can do that. I preferred a minimalist approach since we are in "hard-freeze"
and I wanted to make the change for 2.7 .


>> I guess we could just set VIRTIO_PCI_FLAG_DISABLE_LEGACY, avoid clearing it.
>
> I think we should simply drop the flags and use bool variables instead.
>

You mean OnOffAuto new fields, right?
We would need a wrapper since "auto" mode is not an actual value.
But is doable, of course.

> Also while being at it:  Should we enable modern by default for all pci
> devices?
>

I am not against it, if Michael approves I'll change that too, even for 2.7

Thanks,
Marcel



> cheers,
>    Gerd
>