On Fri, Feb 04, 2022 at 03:15:02PM +0100, Hannes Reinecke wrote:

quoted

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.