[PATCH] nvme: associate stripe size quirk with D4512

[Keith Busch]

On Thu, Jul 02, 2020 at 04:26:21PM -0600, David Fugate wrote:
> On Thu, 2020-07-02 at 14:48 -0700, Keith Busch wrote:
> > On Thu, Jul 02, 2020 at 03:16:04PM -0600, David Fugate wrote:
> > > Did hear from our D4512 team there are concerns with this drive
> > > advertising itself as NVMe 1.2 compliant while also implementing
> > > aspects of NVMe 1.3 such as NOIOB. Of course the Linux NVMe driver
> > > does the right thing in terms of ignoring the drive-reported spec
> > > compliance value in favor of feature detection. Can't be certain
> > > that's the case with all other OSes and closed-source drivers
> > > in particular.
> > 
> > I don't understand this concern. If a driver fails to detect a
> > feature,
> > then they're in the exact same situation as if the controller didn't
> > implement it.
> 
> Imagine a less-enlightened NVMe driver which guards enablement of
> features based *both* on the NVMe spec version the controller reports
> as well as feature detection. In such cases, it wouldn't matter if a
> drive implemented NOIOB (NVMe 1.3) if the controller advertises itself
> as 1.2. 

That's exactly my point. It doesn't matter for these theoretical drivers
whether you implement the feature or not. Meanwhile, 5 years worth of
existing drivers can readily use it. You stand to gain something by
implementing it, and nothing to lose.