Re: [PATCH v6 07/21] libnvdimm, nfit: regions (block-data-window, persistent memory, volatile memory)

From: Rafael J. Wysocki
Date: Wed Jun 17 2015 - 17:37:56 EST

On Thursday, June 11, 2015 04:10:47 PM Dan Williams wrote:
> A "region" device represents the maximum capacity of a BLK range (mmio
> block-data-window(s)), or a PMEM range (DAX-capable persistent memory or
> volatile memory), without regard for aliasing. Aliasing, in the
> dimm-local address space (DPA), is resolved by metadata on a dimm to
> designate which exclusive interface will access the aliased DPA ranges.
> Support for the per-dimm metadata/label arrvies is in a subsequent
> patch.
> The name format of "region" devices is "regionN" where, like dimms, N is
> a global ida index assigned at discovery time. This id is not reliable
> across reboots nor in the presence of hotplug. Look to attributes of
> the region or static id-data of the sub-namespace to generate a
> persistent name. However, if the platform configuration does not change
> it is reasonable to expect the same region id to be assigned at the next
> boot.
> "region"s have 2 generic attributes "size", and "mapping"s where:
> - size: the BLK accessible capacity or the span of the
> system physical address range in the case of PMEM.
> - mappingN: a tuple describing a dimm's contribution to the region's
> capacity in the format (<nmemX>,<dpa>,<size>). For a PMEM-region
> there will be at least one mapping per dimm in the interleave set. For
> a BLK-region there is only "mapping0" listing the starting DPA of the
> BLK-region and the available DPA capacity of that space (matches "size"
> above).
> The max number of mappings per "region" is hard coded per the
> constraints of sysfs attribute groups. That said the number of mappings
> per region should never exceed the maximum number of possible dimms in
> the system. If the current number turns out to not be enough then the
> "mappings" attribute clarifies how many there are supposed to be. "32
> should be enough for anybody...".
> Cc: Neil Brown <neilb@xxxxxxx>
> Cc: <linux-acpi@xxxxxxxxxxxxxxx>
> Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Robert Moore <robert.moore@xxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>

For the ACPI part:

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

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