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

> From: Dan Williams <dan.j.williams(a)intel.com&gt; > Sent: Thursday, March 21, 2019 9:13 PM > > ... > > Actually, this _is_ an issue for NVDIMM_FAMILY_HYPERV (and the other > > families except for NVDIMM_FAMILY_INTEL) : see the kernel function > > acpi_nfit_register_dimms(), where ND_CMD_SMART is set in the > > "cmd_mask" only for NVDIMM_FAMILY_INTEL. > > > > So, on Hyper-V, ndctl_dimm_is_cmd_supported(dimm, ND_CMD_SMART) > > is always false, and "ndctl monitor" exits with "no smart support". > > Can the Hyper-V implementation emulate those commands? That's the > expectation, i.e. that the implementation can return they required > payloads, but it's fine if the payloads disclaim support for certain > fields. Hyper-V Virtual NVDIMM doesn't emulate ND_CMD_SMART(1). The _DSM Function 1 on Hyper-V is "Get Health Information" [1], which is incomptabile with NVDIMM_FAMILY_INTEL's ND_CMD_SMART(1). Even if Hyper-V could emulate ND_CMD_SMART, the current "ndctl monitor" code still wouldn't work for Hyper-V (and the other families): the essence of the issue is that: 1. the kernel only sets ND_CMD_SMART flag for NVDIMM_FAMILY_INTEL. 2. "ndctl monitor" assumes the ND_CMD_SMART should be set by checking /sys/class/nd/ndctl0/device/nmem0/commands. This means ndctl_dimm_is_cmd_supported(dimm, ND_CMD_SMART) can only be true on NVDIMM_FAMILY_INTEL. My patch skips the assumption of ndctl on Hyper-V, so "ndctl monitor" can work on Hyper-V. It looks we do need an ops->monitor_supported() in ndctl?