RE: [ndctl PATCH v2 4/4] ndctl, monitor: support NVDIMM_FAMILY_HYPERV

[Dexuan Cui <decui-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>]

> From: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Sent: Thursday, March 21, 2019 11:12 PM
> To: Dexuan Cui <decui-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>
> 
> On Thu, Mar 21, 2019 at 11:03 PM Dexuan Cui <decui-0li6OtcxBFHby3iVrkZq2A@public.gmane.org> wrote:
> >
> > > From: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> > > Sent: Thursday, March 21, 2019 10:37 PM
> > >
> > > No, I think you misunderstand. Hyper-V implements "function-1",
> > > "command-1" support can be emulated. The request is to translate the
> > > Hyper-V function-1 payload into the command-1 payload format.
> >
> > Then, yes, I think so. The first 2 patches of this patchset do the translation:
> >
> > [ndctl,v2,1/4] libndctl: add support for NVDIMM_FAMILY_HYPERV's _DSM
> Function 1
> > [ndctl,v2,2/4] libndctl: NVDIMM_FAMILY_HYPERV:
> add .smart_get_shutdown_count (Function 2)
> >
> > The problem is how to skip the checkings in ndctl/monitor.c: filter_dimm() on
> Hyper-V.
> > If we return early in filter_dimm(), mfa->num_dimm will be zero, then
> monitor_event()
> > can't be called, and we have no chance to monitor the events and do the
> translation.
> 
> I'd rather change ndctl_dimm_cmd_is_supported() to call back into a
> dimm-op so that the Hyper-V implementation can say "yes, I support
> (emulate) the necessary monitor commands".

Hi Dan,
Then we need to add a new dimm-op monitor_supported(), and change 
ndctl/lib/intel.c and ndctl/lib/hyper.c to implement the new dimm-op, and we
need to change the common code, i.e. ndctl_dimm_cmd_is_supported(), to use
this new dimm-op.

If this sounds reasonable to you and Verma, I'll try to make a patchset for you
to review.

Thanks,
-- Dexuan