[RFC PATCH 3/3] nvme: add the "debug" host driver

[Christoph Hellwig]

On Fri, Feb 04, 2022 at 03:15:02PM +0100, Hannes Reinecke wrote:
>> ZNS kernel code testing is also done on QEMU, I've also fixed
>> bugs in the ZNS kernel code which are discovered on QEMU and I've not
>> seen any issues with that. Given that simple copy feature is way smaller
>> than ZNS it will less likely to suffer from slowness and etc (listed
>> above) in QEMU.
>>
>> my point is if we allow one, we will be opening floodgates and we need
>> to be careful not to bloat the code unless it is _absolutely
>> necessary_ which I don't think it is based on the simple copy
>> specification.
>>
>
> I do have a slightly different view on the nvme target code; it should 
> provide the necessary means to test the nvme host code.
> And simple copy is on of these features, especially as it will operate as 
> an exploiter of the new functionality.

Well, in general I'd like to have every useful feature supported in
nvmet, because it serves both testing and production.  If a feature
isn't all that useful (and there are lots of those in nvme these days)
we don't need to support in nvmet, but probably neither in the host code.