[PATCH V2 0/2] nvme: Support user mode processing of ZNS Zone Changed AEN

[Chaitanya Kulkarni]

>>> This support is planned to be used by both zone based applications and
>>> another unreleased device with an alternate command set.
>>>
>>>
>>
>> Please write a testcase in the blktest to this will get tested every
>> release.
>>
>> -ck
> 
> Ok - I'll give it a go to implement that but AENs by definition aren't a
> response to a request (mostly) - they just happen.  The case that I know

and this is exactly the main reason we need a testcase since it is
sporadic and side effect of the controller's behavior that cannot be 
predicted (untill it hits the condition) by the requests.
Lack of the testcase will leave this code untested unlike
other code paths which are getting exercised predictably.

> of that creates a zone excursion AEN takes many hours to manifest and
> that duration would be FLASH-type specific.  I don't know how you could
> use a real device.
> 

For this using real device is not an option since everyone should be
able to test that with ease in blktests.

> This patch was tested under QEMU with our custom emulator.  The
> current QEMU NVMe/ZNS device doesn't emulate zone excursions so I'll
> have to start there unless someone knows of a better way.
> 

Please add the support our QEMU NVMe developers are very helpful to get 
new features in.

-ck