Virtualization - Jun 2021 - [PATCH v8 00/10] Introduce VDUSE - vDPA Device in Userspace

? 2021/6/29 ??2:40, Yongji Xie ??:
> On Tue, Jun 29, 2021 at 12:13 PM Jason Wang <jasowang at redhat.com>
wrote:
>>
>> ? 2021/6/28 ??6:32, Yongji Xie ??:
>>>> The large barrier is bounce-buffer mapping: SPDK requires
hugepages
>>>> for NVMe over PCIe and RDMA, so take some preallcoated
hugepages to
>>>> map as bounce buffer is necessary. Or it's hard to avoid an
extra
>>>> memcpy from bounce-buffer to hugepage.
>>>> If you can add an option to map hugepages as bounce-buffer,
>>>> then SPDK could also be a potential user of vduse.
>>>>
>>> I think we can support registering user space memory for
bounce-buffer
>>> use like XDP does. But this needs to pin the pages, so I didn't
>>> consider it in this initial version.
>>>
>> Note that userspace should be unaware of the existence of the bounce
buffer.
>>
> If so, it might be hard to use umem. Because we can't use umem for
> coherent mapping which needs physical address contiguous space.
>
> Thanks,
> Yongji

We probably can use umem for memory other than the virtqueue (still via 
mmap()).

Thanks