What should we do about the nvme atomics mess?

[Chaitanya Kulkarni]

On 7/7/25 08:56, Keith Busch wrote:
> On Mon, Jul 07, 2025 at 05:26:46PM +0200, Hannes Reinecke wrote:
>> On 7/7/25 16:24, Keith Busch wrote:
>>> On Mon, Jul 07, 2025 at 04:18:34PM +0200, Christoph Hellwig wrote:
>>>> We could:
>>>>
>>>>    I.	 revert the check and the subsequent fixup.  If you really want
>>>>            to use the nvme atomics you already better pray a lot anyway
>>>> 	 due to issue 1)
>>>>    II.	 limit the check to multi-controller subsystems
>>>>    III.	 don't allow atomics on controllers that only report AWUPF and
>>>>    	 limit support to controllers that support that more sanely
>>>> 	 defined NAWUPF
>>>>
>>>> I guess for 6.16 we are limited to I. to bring us back to the previous
>>>> state, but I have a really bad gut feeling about it given the really
>>>> bad spec language and a lot of low quality NVMe implementations we're
>>>> seeing these days.
>>> I like option III. The controler scoped atomic size is broken for all
>>> the reasons you mentioned, so I vote we not bother trying to make sense
>>> of it.
>>>
>> Agree. We might consider I. as a fixup for stable, but should continue
>> with III going forward.
> I think the NVMe TWG might want to consider an ECN to deprecate or at
> least recommend against AUWPF, too.

We should really find a way to fix this in the spec, I'll be happy to add
this topic and agenda so we can discuss it at a length, before that happens
option III seems right way to fix it.

-ck