Re: [PATCH v4 0/6] vhost-user-blk: fix compatibility with older qemu versions

On 7/25/26 10:32, Michael S. Tsirkin wrote:
> On Thu, Jul 16, 2026 at 12:30:33PM +0500, Alexandr Moshkov wrote:
>> Ping :)
Thanks for reply!
>
> I don't know what to do with this one. IIUC in flight migration is in 11.0
> so I doubt we can just introduce new messages without a protocol flag.

The original plan was to push this series before the 11.0 release, using 
the existing VHOST_USER_PROTOCOL_F_GET_VRING_BASE_INFLIGHT flag - since 
the new message is a direct extension of that feature.
Now I agree that we need a separate protocol feature flag (like 
VHOST_USER_PROTOCOL_F_GET_VRING_BASE_SKIP_DRAIN) for new 
GET_VRING_BASE_SKIP_DRAIN message.

>
> It says fix compatibility but really it's a feature, right?
I called it a "fix" because I saw missing migration compatibility as a 
deficiency, but from protocol perspective its more like "feature" - 
you're right. I'll update the subject.
>
> And this is somehow related to GET_BASE?
Yes, GET_VRING_BASE_SKIP_DRAIN is a variant of GET_VRING_BASE - it stops 
the vring the same way, but tells the backend to immediately suspend 
in-flight I/O, rather than wait for it to complete.
>
> Half the commits here have no or a single line of comment, those that
> do, repeat what the commit does instead of explaining why.
>
> That's not how it should be.
>
> Here's a good template to use:
>
> Currently .... This is a problem because ... We can not do .... because
> ... To address .... And then ....
Agreed, the descriptions are poor. I'll rewrite them following your 
template. Thanks!
>
> HTH
>