RE: [PATCH] libnvdimm/dimm: Add a no-BLK quirk based on NVDIMM family

[Dexuan Cui]

> From: Dan Williams <dan.j.williams@xxxxxxxxx>
> Sent: Saturday, February 2, 2019 5:13 PM
> ...
> As Dexuan reports the NVDIMM_FAMILY_HYPERV platform is incompatible with
> the existing Linux namespace implementation because it uses
> NSLABEL_FLAG_LOCAL for x1-width PMEM interleave sets. Quirk it as an
> platform / DIMM that does not provide BLK-aperture access. Allow the
> libnvdimm core to assume no potential for aliasing. In case other
> implementations make the same mistake, provide a "noblk" module
> parameter to force-enable the quirk.

Hi Dan,
Thanks very much for the patch! With it, "ndctl list" can show the below:

root@decui-gen2-u1904:~/ndctl# ndctl list
[
  {
    "dev":"namespace1.0",
    "mode":"raw",
    "size":137438953472,
    "uuid":"c258aaab-f72b-e546-bfa5-be5e07761dbc",
    "blockdev":"pmem1",
    "name":"Microsoft Hyper-V NVDIMM 1 Label"
  },
  {
    "dev":"namespace0.0",
    "mode":"raw",
    "size":34359738368,
    "uuid":"9f0497a7-4453-7c40-ad35-21a791e00345",
    "blockdev":"pmem0",
    "name":"Microsoft Hyper-V NVDIMM 0 Label"
  }
]

And /dev/pmem0 can appear, but /dev/pmem0p1 can not appear, and the "mode" of
"namespace0.0" is not correct.  With the Ubuntu 19.04 4.18 kenel, I get the below:

root@decui-gen2-u1904:~/ndctl# ndctl list
[
  {
    "dev":"namespace1.0",
    "mode":"raw",
    "size":137438953472,
    "blockdev":"pmem1"
  },
  {
    "dev":"namespace0.0",
    "mode":"fsdax",
    "map":"dev",
    "size":33820770304,
    "uuid":"ef028c4e-2b1f-4bf8-b92a-1109d7a1c914",
    "blockdev":"pmem0"
  }
]
and /dev/pmem0p1 can appear.

It looks the namespace created by Ubuntu 19.04 (4.18) is incompatible with
the libnvdimm-pending branch + this patch.

It looks we need to completely disable the label usage for NVDIMM_FAMILY_HYPERV 
due to compability?

Thanks,
-- Dexuan