Re: [PATCH vfio 10/11] vfio/virtio: Expose admin commands over virtio device

["Zhu, Lingshan" <lingshan.zhu@xxxxxxxxx>]

On 10/12/2023 9:27 PM, Jason Gunthorpe wrote:

> On Thu, Oct 12, 2023 at 06:29:47PM +0800, Zhu, Lingshan wrote:
>
> > sorry for the late reply, we have discussed this for weeks in virtio mailing
> > list. I have proposed a live migration solution which is a config space solution.
> >       
> I'm sorry that can't be a serious proposal - config space can't do
> DMA, it is not suitable.
>     
    config space only controls the live migration
      process and config the related facilities.
      We don't use config space to transfer data.
      
      The new added registers work like queue_enable or features.
      
      For example, we use DMA to report dirty pages and MMIO to fetch
      the dirty data.
      
      I remember in another thread you said:"you can't use DMA for any migration flows"
      
      And I agree to that statement, so we use config space registers to
      control the flow.
      
      Thanks,
      Zhu Lingshan
    
> Jason
>     
    
    
  

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