Re: [Qemu-devel] [PATCH v2 4/7] scripts/qemu.py: set predefined machine type based on arch

[Cleber Rosa]

On 10/10/18 9:59 AM, Cleber Rosa wrote:
> 
> 
> On 10/10/18 9:46 AM, Eduardo Habkost wrote:
>> On Wed, Oct 10, 2018 at 08:35:38AM -0400, Cleber Rosa wrote:
>>>
>>>
>>> On 10/10/18 7:00 AM, Philippe Mathieu-Daudé wrote:
>>>> On 10/10/2018 01:26, Cleber Rosa wrote:
>>>>> Some targets require a machine type to be set, as there's no default
>>>>> (aarch64 is one example).  To give a consistent interface to users of
>>>>> this API, this changes set_machine() so that a predefined default can
>>>>> be used, if one is not given.  The approach used is exactly the same
>>>>> with the console device type.
>>>>>
>>>>> Also, even when there's a default machine type, for some purposes,
>>>>> testing included, it's better if outside code is explicit about the
>>>>> machine type, instead of relying on whatever is set internally.
>>>>>
>>>>> Signed-off-by: Cleber Rosa <address@hidden>
>>>>> ---
>>>>>  scripts/qemu.py | 22 +++++++++++++++++++++-
>>>>>  1 file changed, 21 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/scripts/qemu.py b/scripts/qemu.py
>>>>> index d9e24a0c1a..fca9b76990 100644
>>>>> --- a/scripts/qemu.py
>>>>> +++ b/scripts/qemu.py
>>>>> @@ -36,6 +36,15 @@ CONSOLE_DEV_TYPES = {
>>>>>      r'^s390-ccw-virtio.*': 'sclpconsole',
>>>>>      }
>>>>>  
>>>>> +#: Maps archictures to the preferred machine type
>>>>> +MACHINE_TYPES = {
>>>>> +    r'^aarch64$': 'virt',
>>>>> +    r'^ppc$': 'g3beige',
>>>>> +    r'^ppc64$': 'pseries',
>>>>> +    r'^s390x$': 's390-ccw-virtio',
>>>>> +    r'^x86_64$': 'q35',
>>>>
>>>> Why choose Q35 rather than PC (the default)?
>>>>
>>>> I was wondering about how to generate variants/machines.json but this is
>>>> definitively something we want to do via a QMP query.
>>>>
>>>> Eduardo what do you think?
>>>>
>>>
>>> It was motivated by Eduardo's initiative to make q35 the default "across
>>> the board".  He can confirm and give more details.
>>
>> Making Q35 the default on applications using QEMU and libvirt is
>> something I'd like to happen.  But I think the simplest way to do
>> that is to change the QEMU default.  This way you won't need this
>> table on qemu.py: you can just use the default provided by QEMU.
>>
> 
> The idea is to bring consistency on how we're calling
> "qemu-system-$(ARCH)", and at the same time apply the "explicit is
> better than implicit" rule.
> 
> The most important fact is that some targets do not (currently) have
> "the default provided by QEMU", aarch64 is one of them.
> 
> - Cleber.
> 

So I ended up not relaying the question properly: should we default
(even if explicitly adding "-machine") to "pc"?

Thanks!
- Cleber.