nvme lightnvm comments

[Christoph Hellwig]

On Mon, Nov 23, 2015 at 04:03:20PM +0000, Keith Busch wrote:
> We also thought it'd have been cleaner to have a different command set,
> but the committee hasn't taken on assigning these reserved bits for any
> new purposes yet. LightNVM detection is done with the vendor + device
> id at the moment.

I saw the vendor + device, but even with that I'd rather see a reserved
value in the command set in addition.  Claiming that we're NVM if we're
not is a bad idea.

While we're at it - the NVMe driver really should check for these
reserved bits and reject a PCIe device that doesn't claim to implement
the NVM command set.