Re: [PATCH] qapi, machine-qmp-cmds.c: query-accelerator support

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 2/10/24 20:06, Daniel Henrique Barboza wrote:
> 
> 
> On 9/27/24 7:50 AM, Daniel P. Berrangé wrote:
>> Markus: QAPI design Qs for you at the bottom
>>
>> On Wed, Sep 25, 2024 at 10:19:33AM -0300, Daniel Henrique Barboza wrote:
>>>
>>>
>>> On 9/19/24 9:22 AM, Daniel P. Berrangé wrote:
>>>> On Thu, Sep 19, 2024 at 08:20:56AM -0300, Daniel Henrique Barboza 
>>>> wrote:
>>>>> Add a QMP command that shows all specific properties of the current
>>>>> accelerator in use.
>>>>
>>>> Why do we need to expose /everything/ ?
>>>
>>> I wouldn't mind pick and choose advertised properties for the 
>>> accelerators
>>> like we do with other APIs.
>>>
>>> This would mean that each arch should choose what to advertise or 
>>> not, given that
>>> some accelerator properties might be relevant just for some archs. 
>>> The API would
>>> be implemented by each arch individually.
>>
>> Well with qemu-system-any we might get multiple arches reporting
>> info in the same binary, so we'll need to fan out to fill in the
>> per-arch info, after doing a common base.
>>
>> Hmmm, i wonder if qemu-system-any will support mixing KVM and TCG ?
>> ie KVM for the host native accelerator, combined with TCG for the
>> foreign archs ??? Hopefully not !
> 
> If you're talking about Phil's patches it seems that it'll be TCG only:

Orthogonaly to the single binary series (mentioned below with the
'any'-architecture target), we plan to add a "Dual HW/SW accelerator".
It will be implemented using the same AccelOps structure we currently
have, and internally it will dispatch between HW/SW. First prototype
plan to provide HVF+TCG.

IMHO query-accelerator should expose accelerator generic properties,
not the target-specific ones. At least by default, we could add an
optional flag to include target-specific stuff. At least that'd keep
the core accel core simpler.

> https://lore.kernel.org/qemu-devel/20240305220938.85410-1-philmd@linaro.org/
> 
> Patch 2 commit msg states:
> 
> ------
> Add the 'any'-architecture target.
> 
> - Only consider 64-bit targets
> - Do not use any hardware accelerator (except qtest)
> - For architecture constants, use:
>    . max of supported targets phys/virt address space
>    . max of supported targets MMU modes
>    . min of supported targets variable page bits
> ------
> 
> 
> Thanks,
> 
> Daniel