# Re: \[PATCH v1\] vdpa/mlx5: Restore the hardware used index after change map

- From: Si-Wei Liu \<hidden\>
- Date: 2021-02-20 03:01:01 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/02/6274296
- Thread: https://ratatoskr.run/netdev/2021/02/6258157/t.md

```text


On 2/19/2021 6:38 PM, Jason Wang wrote:
>>>
>>>
>>> Right now the value is exposed to userspace via GET_VRING_BASE, so only last_avail_idx is synced. If we need sync last_used_idx, we should also sync pending indices which requires more thoughts.
>> Technically it doesn't sound right - crossing the boundary a bit even with simplified form of assumption. But depending on how userspace could make use of this API, it doesn't seem it breaks existing functionality for the moment.
>
>
> I don't get here, maybe you can explain a little bit more? Please refer to the email I just sent.

https://lore.kernel.org/lkml/033b0806-4037-5755-a1fa-91dbb58bab2e@oracle.com/

-Siwei
```