Re: [Qemu-devel] [RFC v2 0/4] adding mdev bus and vfio support

[Jike Song]

On 09/08/2016 12:56 AM, Alex Williamson wrote:
> On Wed, 07 Sep 2016 14:42:58 +0800
> Jike Song <address@hidden> wrote:
> 
>> On 09/07/2016 11:38 AM, Neo Jia wrote:
>>> On Wed, Sep 07, 2016 at 10:22:26AM +0800, Jike Song wrote:  
>>>> On 09/02/2016 11:03 PM, Alex Williamson wrote:  
>>>>> On Fri,  2 Sep 2016 16:16:08 +0800
>>>>> Jike Song <address@hidden> wrote:
>>>>>  
>>>>>> This patchset is based on NVidia's "Add Mediated device support" series, 
>>>>>> version 6:
>>>>>>
>>>>>>  http://www.spinics.net/lists/kvm/msg136472.html  
>>>>>
>>>>>
>>>>> Hi Jike,
>>>>>
>>>>> I'm thrilled by your active participation here, but I'm confused which
>>>>> versions I should be reviewing and where the primary development is
>>>>> going.  Kirti sent v7 a week ago, so I would have expected a revision
>>>>> based on that rather than a re-write based on v6 plus incorporation of a
>>>>> few of Kirti's patches directly.  
>>>>
>>>> Hi Alex,
>>>>
>>>> [Sorry! replied this on Monday but it was silently dropped by the our 
>>>> firewall]
>>>>
>>>>
>>>>
>>>> The v1 of this patchset was send as incremental ones, basing on Nvidia's 
>>>> v6, to
>>>> demonstrate how is it possible and beneficial to:
>>>>
>>>>    1, Introduce an independent device between physical and mdev;
>>>>    2, Simplify vfio-mdev and make it the most flexible for vendor drivers;
>>>>
>>>> Unfortunately neither was understood or adopted in v7:
>>>>
>>>>    http://www.spinics.net/lists/kvm/msg137081.html
>>>>
>>>> So here came the v2, as a standalone series, to give a whole and straight
>>>> demonstration. The reason of still basing on v6:
>>>>
>>>>    - Addressed all v6 comments (except the iommu part);
>>>>    - There is no comments yet for v7 (except the sysfs ones);
>>>>
>>>>
>>>>  
>>>>> I liked the last version of these
>>>>> changes a lot, but we need to figure out how to combine development
>>>>> because we do not have infinite cycles for review available :-\  Thanks!  
>>>>
>>>> Fully understand.
>>>>
>>>> Here is the dilemma: v6 is an obsolete version to work upon, v7 is still 
>>>> not
>>>> at the direction we prefer.   
>>>
>>> Hi Jike,
>>>
>>> I wish I could meet you in person in KVM forum couple weeks ago so we can 
>>> have a
>>> better discussion.  
>>
>> I wish I could have that opportunity, too!
>>
>>> We are trying our best to accommodate almost all requirements / comments 
>>> from 
>>> use cases and code reviews while keeping little (or none) architectural 
>>> changes
>>> between revisions.  
>>
>> Yes I saw that, there was little architectural change from v6 to v7,
>> that's what I will argue for :)
>>
>>>> We would be highly glad and thankful if Neo/Kirti
>>>> would adopt the code in their next version, which will certainly form a
>>>> more simple and consolidated base for future co-development; otherwise
>>>> and we could at least discuss the concerns, in case of any.
>>>>  
>>>
>>> As I have said in my previous response to you, if you have any questions 
>>> about
>>> adopting the framework that we have developed, you are very welcome to
>>> comment/speak out on the code review thread like others. And if it is 
>>> reasonable
>>> request and won't break other vendors' use case, we will adopt it (one 
>>> example
>>> is the online file and removing the mdev pci dependency).
>>>   
>>
>> Not limited to having questions about adoption, right? :)
>>
>> We do think the framework itself had too much unnecessary logic and
>> imposed limitations to vendor drivers, also it's clearly possible to be
>> simplified.
>>
>>> Just some update for you regarding the v7 patches, currently we are very
>>> actively trying to lock down the sysfs and management interfaces discussion.
>>>
>>> So, if you would like to make the upstream happen sooner, please join us in 
>>> the
>>> v7 and following patch discussion instead of rewriting them.
>>>   
>>
>> So as you said, I would comment on the v7 series to propose both 
>> architectural
>> and implementation changes, hoping this will help more.
> 
> Please do, I definitely like where you're heading and I want to see
> Kirti and Neo include your ideas.  The challenge is to try to focus our
> efforts into a single development stream.  Please continue to comment
> and even submit patches, but let's consider NVIDIA's latest patches to
> be the main development stream and request changes against that.  As
> you would do upstream, propose changes in small increments where we can
> evaluate each step.  It's very difficult for Neo and Kirti to
> incorporate bulk rewrites.  Thanks,
> 

Thanks - We'll try our best to meet that!


--
Thanks,
Jike