Clarification regarding "nvme discover" and setting IOSQES/IOCQES

[Keith Busch]

On Mon, Feb 08, 2021 at 03:01:28PM -0800, Sagi Grimberg wrote:
> 
> > > > Hi Sagi,
> > > > 
> > > > Yes. The Discovery Controller currently allows it. The problem, however,
> > > > is that the DC seems to be expecting these values to be non-zero.
> > > > 
> > > > I tried setting IOCQES=0 and IOSQES=0, which the DC allows (i.e. Prop
> > > > Set return status=0). However, when I follow this by a "Property Get -
> > > > Controller Status", the Status now shows "Controller Fatal Status (CFS)"
> > > > (see Base specs - Figure 79).
> > > 
> > > Yes, the oversight extends to the target that expects it (shared code
> > > with I/O controllers).
> > > 
> > > Does this fix your issue?
> > 
> > Seems like the Identify Controller SQES and CQES fields ought to be
> > updated too, but the spec isn't clear on this. Feels like ECN
> > material...
> 
> Yes, we should start with this patch though right?

Yep, your patch looks good.

I was just thinking a generic implementation could align the CC settings with
the ID_CTRL values rather than checking for a discovery controller, but I
noticed the spec didn't provide us that opportunity. That was actually a
misguided thought anyway since we don't even have ID_CTRL data on the initial
CC setting! :)