Re: [PATCH v5 4/8] vt82c686: Introduce abstract TYPE_VIA_ISA and base vt82c686b_isa on it

[Philippe Mathieu-Daudé]

On 3/5/21 2:02 AM, David Gibson wrote:
> On Thu, Mar 04, 2021 at 11:42:10PM +0100, Philippe Mathieu-Daudé wrote:
>> On 3/4/21 9:16 PM, BALATON Zoltan wrote:
>>> On Thu, 4 Mar 2021, Philippe Mathieu-Daudé wrote:
>>>> On 3/2/21 10:11 PM, BALATON Zoltan wrote:
>>>>> To allow reusing ISA bridge emulation for vt8231_isa move the device
>>>>> state of vt82c686b_isa emulation in an abstract via_isa class.
>>>>>
>>>>> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
>>>>> ---
>>>>>  hw/isa/vt82c686.c        | 70 ++++++++++++++++++++++------------------
>>>>>  include/hw/pci/pci_ids.h |  2 +-
>>>>>  2 files changed, 40 insertions(+), 32 deletions(-)
>>>>>
>>>>> diff --git a/hw/isa/vt82c686.c b/hw/isa/vt82c686.c
>>>>> index 72234bc4d1..5137f97f37 100644
>>>>> --- a/hw/isa/vt82c686.c
>>>>> +++ b/hw/isa/vt82c686.c
>>>>> @@ -609,24 +609,48 @@ static const TypeInfo vt8231_superio_info = {
>>>>>  };
>>>>>
>>>>>
>>>>> -OBJECT_DECLARE_SIMPLE_TYPE(VT82C686BISAState, VT82C686B_ISA)
>>>>> +#define TYPE_VIA_ISA "via-isa"
>>>>> +OBJECT_DECLARE_SIMPLE_TYPE(ViaISAState, VIA_ISA)
>>>>>
>>>>> -struct VT82C686BISAState {
>>>>> +struct ViaISAState {
>>>>>      PCIDevice dev;
>>>>>      qemu_irq cpu_intr;
>>>>>      ViaSuperIOState *via_sio;
>>>>>  };
>>>>>
>>>>> +static const VMStateDescription vmstate_via = {
>>>>> +    .name = "via-isa",
>>>>
>>>> You changed the migration stream name, so I think we have
>>>> a problem with migration... No clue how to do that properly.
>>>
>>> I don't think these machines support migration or state description of
>>> vt86c686b was not missing something before these patches that would make
>>> it not work anyway so I did not worry about this too much. I doubt
>>> anybody wants to migrate a fuloong2e machine so this should not be a
>>> problem in practice but maybe you can mention it in the release notes if
>>> you think that would be necessary.
>>
>> Maybe just add in the description:
>>
>>  This change breaks migration back compatibility, but
>>  this is not an issue for the Fuloong2E machine.
> 
> Hrm.  If migration was never supported, why is there a vmstate
> description there at all though?
> 
> That said, I don't think breaking compat is a problem: that's only an
> issue where we actually have versioned machine types, which covers
> only pc, pseries, arm virt and a very few others.  I don't think this
> device was used on any of them.

OK. Can you provide a formal Ack-by tag then? :)