Re: [PATCH 2/2] vDPA: conditionally read fields in virtio-net dev

Zhu, Lingshan
2022-08-17T09:43:38Z

On 8/17/2022 5:39 PM, Michael S. Tsirkin wrote:
> On Wed, Aug 17, 2022 at 05:13:59PM +0800, Zhu, Lingshan wrote:
>>
>> On 8/17/2022 4:55 PM, Michael S. Tsirkin wrote:
>>> On Wed, Aug 17, 2022 at 10:14:26AM +0800, Zhu, Lingshan wrote:
>>>> Yes it is a little messy, and we can not check _F_VERSION_1 because of
>>>> transitional devices, so maybe this is the best we can do for now
>>> I think vhost generally needs an API to declare config space endian-ness
>>> to kernel. vdpa can reuse that too then.
>> Yes, I remember you have mentioned some IOCTL to set the endian-ness,
>> for vDPA, I think only the vendor driver knows the endian,
>> so we may need a new function vdpa_ops->get_endian().
>> In the last thread, we say maybe it's better to add a comment for now.
>> But if you think we should add a vdpa_ops->get_endian(), I can work
>> on it for sure!
>>
>> Thanks
>> Zhu Lingshan
> I think QEMU has to set endian-ness. No one else knows.
Yes, for SW based vhost it is true. But for HW vDPA, only
the device & driver knows the endian, I think we can not
"set" a hardware's endian.

So if you think we should add a vdpa_ops->get_endian(),
I will drop these comments in the next version of
series, and work on a new patch for get_endian().

Thanks,
Zhu Lingshan
>