Re: [Linux-nvdimm] [PATCH 08/21] nd: ndctl.h, the nd ioctl abi

[Dan Williams]

On Fri, Apr 24, 2015 at 8:56 AM, Toshi Kani <toshi.kani@xxxxxx> wrote:
> On Fri, 2015-04-17 at 21:35 -0400, Dan Williams wrote:
>> Most configuration of the nd-subsystem is done via nd-sysfs.  However,
>> the NFIT specification defines a small set of messages that can be
>> passed to the subsystem via platform-firmware-defined methods.  The
>> command set (as of the current version of the NFIT-DSM spec) is:
>>
>>     NFIT_CMD_SMART: media health and diagnostics
>>     NFIT_CMD_GET_CONFIG_SIZE: size of the label space
>>     NFIT_CMD_GET_CONFIG_DATA: read label
>>     NFIT_CMD_SET_CONFIG_DATA: write label
>>     NFIT_CMD_VENDOR: vendor-specific command passthrough
>>     NFIT_CMD_ARS_CAP: report address-range-scrubbing capabilities
>>     NFIT_CMD_START_ARS: initiate scrubbing
>>     NFIT_CMD_QUERY_ARS: report on scrubbing state
>>     NFIT_CMD_SMART_THRESHOLD: configure alarm thresholds for smart events
>
> "nd/bus.c" provides two features, 1) the top level ND bus driver which
> is the central part of the ND, and 2) the ioctl interface specific to
> the example-DSM-interface.  I think the example-DSM-specific part should
> be put into an example-DSM-support module, so that the ND can support
> other _DSMs as necessary.  Also, _DSM needs to be handled as optional.

I don't think it needs to be separated, they'll both end up using the
same infrastructure just with different UUIDs on the ACPI device
interface or different format-interface-codes.  A firmware
implementation is also free to disable individual DSMs (see
nd_acpi_add_dimm).  That said, you're right, we do need a fix to allow
PMEM from DIMMs without DSMs to activate.
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