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SubjectRe: [Linux-nvdimm] [PATCH 08/21] nd: ndctl.h, the nd ioctl abi
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On Fri, 2015-04-24 at 09:25 -0700, Dan Williams wrote:
> On Fri, Apr 24, 2015 at 8:56 AM, Toshi Kani <toshi.kani@hp.com> 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).

Well, ioctl cmd# is essentially func# of the _DSM, and each cmd
structure needs to match with its _DSM output data structure. So, I do
not think these cmds will work for other _DSMs. That said, the ND is
complex enough already, and we should not make it more complicated for
the initial version... So, how about changing the name of /dev/ndctl0
to indicate RFIC 0x0201, ex. /dev/nd0201ctl0? That should allow
separate ioctl()s for other RFICs. The code can be updated when other
_DSM actually needs to be supported by the ND.

> That said, you're right, we do need a fix to allow
> PMEM from DIMMs without DSMs to activate.

Great!

Thanks,
-Toshi



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