On 10/13/2023 9:50 PM, Michael S. Tsirkin wrote:
On Fri, Oct 13, 2023 at 06:28:34PM +0800, Zhu, Lingshan wrote: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 JasonIf you are using dma then I don't see what's wrong with admin vq. dma is all it does.
dma != admin vq, and I think we have discussed many details in pros and cons in admin vq live migration proposal in virtio-comment. I am not sure we should span the discussions here, repeat them over again. Thanks
