Merge tag 'libnvdimm-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm updates from Dan Williams:
 "The update for this cycle includes the deprecation of block-aperture
  mode and a new perf events interface for the papr_scm nvdimm driver.

  The perf events approach was acked by PeterZ.

   - Add perf support for nvdimm events, initially only for 'papr_scm'
     devices.

   - Deprecate the 'block aperture' support in libnvdimm, it only ever
     existed in the specification, not in shipping product"

* tag 'libnvdimm-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  nvdimm/blk: Fix title level
  MAINTAINERS: remove section LIBNVDIMM BLK: MMIO-APERTURE DRIVER
  powerpc/papr_scm: Fix build failure when
  drivers/nvdimm: Fix build failure when CONFIG_PERF_EVENTS is not set
  nvdimm/region: Delete nd_blk_region infrastructure
  ACPI: NFIT: Remove block aperture support
  nvdimm/namespace: Delete nd_namespace_blk
  nvdimm/namespace: Delete blk namespace consideration in shared paths
  nvdimm/blk: Delete the block-aperture window driver
  nvdimm/region: Fix default alignment for small regions
  docs: ABI: sysfs-bus-nvdimm: Document sysfs event format entries for nvdimm pmu
  powerpc/papr_scm: Add perf interface support
  drivers/nvdimm: Add perf interface to expose nvdimm performance stats
  drivers/nvdimm: Add nvdimm pmu structure

2 files changed, 123 insertions, 318 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-nvdimm b/Documentation/ABI/testing/sysfs-bus-nvdimm
index bff84a16812a..1c1f5acbf53d 100644
--- a/Documentation/ABI/testing/sysfs-bus-nvdimm
+++ b/Documentation/ABI/testing/sysfs-bus-nvdimm
@@ -6,3 +6,38 @@ Description:
 
 The libnvdimm sub-system implements a common sysfs interface for
 platform nvdimm resources. See Documentation/driver-api/nvdimm/.
+
+What:           /sys/bus/event_source/devices/nmemX/format
+Date:           February 2022
+KernelVersion:  5.18
+Contact:        Kajol Jain <kjain@linux.ibm.com>
+Description:	(RO) Attribute group to describe the magic bits
+		that go into perf_event_attr.config for a particular pmu.
+		(See ABI/testing/sysfs-bus-event_source-devices-format).
+
+		Each attribute under this group defines a bit range of the
+		perf_event_attr.config. Supported attribute is listed
+		below::
+		  event  = "config:0-4"  - event ID
+
+		For example::
+			ctl_res_cnt = "event=0x1"
+
+What:           /sys/bus/event_source/devices/nmemX/events
+Date:           February 2022
+KernelVersion:  5.18
+Contact:        Kajol Jain <kjain@linux.ibm.com>
+Description:	(RO) Attribute group to describe performance monitoring events
+                for the nvdimm memory device. Each attribute in this group
+                describes a single performance monitoring event supported by
+                this nvdimm pmu.  The name of the file is the name of the event.
+                (See ABI/testing/sysfs-bus-event_source-devices-events). A
+                listing of the events supported by a given nvdimm provider type
+                can be found in Documentation/driver-api/nvdimm/$provider.
+
+What:          /sys/bus/event_source/devices/nmemX/cpumask
+Date:          February 2022
+KernelVersion:  5.18
+Contact:        Kajol Jain <kjain@linux.ibm.com>
+Description:	(RO) This sysfs file exposes the cpumask which is designated to
+		to retrieve nvdimm pmu event counter data.
diff --git a/Documentation/driver-api/nvdimm/nvdimm.rst b/Documentation/driver-api/nvdimm/nvdimm.rst
index 1d8302b89bd4..be8587a558e1 100644
--- a/Documentation/driver-api/nvdimm/nvdimm.rst
+++ b/Documentation/driver-api/nvdimm/nvdimm.rst
@@ -14,10 +14,8 @@ Version 13
 	Overview
 	    Supporting Documents
 	    Git Trees
-	LIBNVDIMM PMEM and BLK
-	Why BLK?
-	    PMEM vs BLK
-	        BLK-REGIONs, PMEM-REGIONs, Atomic Sectors, and DAX
+	LIBNVDIMM PMEM
+	    PMEM-REGIONs, Atomic Sectors, and DAX
 	Example NVDIMM Platform
 	LIBNVDIMM Kernel Device Model and LIBNDCTL Userspace API
 	    LIBNDCTL: Context
@@ -53,19 +51,12 @@ PMEM:
   block device composed of PMEM is capable of DAX.  A PMEM address range
   may span an interleave of several DIMMs.
 
-BLK:
-  A set of one or more programmable memory mapped apertures provided
-  by a DIMM to access its media.  This indirection precludes the
-  performance benefit of interleaving, but enables DIMM-bounded failure
-  modes.
-
 DPA:
   DIMM Physical Address, is a DIMM-relative offset.  With one DIMM in
   the system there would be a 1:1 system-physical-address:DPA association.
   Once more DIMMs are added a memory controller interleave must be
   decoded to determine the DPA associated with a given
-  system-physical-address.  BLK capacity always has a 1:1 relationship
-  with a single-DIMM's DPA range.
+  system-physical-address.
 
 DAX:
   File system extensions to bypass the page cache and block layer to
@@ -84,30 +75,30 @@ BTT:
   Block Translation Table: Persistent memory is byte addressable.
   Existing software may have an expectation that the power-fail-atomicity
   of writes is at least one sector, 512 bytes.  The BTT is an indirection
-  table with atomic update semantics to front a PMEM/BLK block device
+  table with atomic update semantics to front a PMEM block device
   driver and present arbitrary atomic sector sizes.
 
 LABEL:
   Metadata stored on a DIMM device that partitions and identifies
-  (persistently names) storage between PMEM and BLK.  It also partitions
-  BLK storage to host BTTs with different parameters per BLK-partition.
-  Note that traditional partition tables, GPT/MBR, are layered on top of a
-  BLK or PMEM device.
+  (persistently names) capacity allocated to different PMEM namespaces. It
+  also indicates whether an address abstraction like a BTT is applied to
+  the namepsace.  Note that traditional partition tables, GPT/MBR, are
+  layered on top of a PMEM namespace, or an address abstraction like BTT
+  if present, but partition support is deprecated going forward.
 
 
 Overview
 ========
 
-The LIBNVDIMM subsystem provides support for three types of NVDIMMs, namely,
-PMEM, BLK, and NVDIMM devices that can simultaneously support both PMEM
-and BLK mode access.  These three modes of operation are described by
-the "NVDIMM Firmware Interface Table" (NFIT) in ACPI 6.  While the LIBNVDIMM
-implementation is generic and supports pre-NFIT platforms, it was guided
-by the superset of capabilities need to support this ACPI 6 definition
-for NVDIMM resources.  The bulk of the kernel implementation is in place
-to handle the case where DPA accessible via PMEM is aliased with DPA
-accessible via BLK.  When that occurs a LABEL is needed to reserve DPA
-for exclusive access via one mode a time.
+The LIBNVDIMM subsystem provides support for PMEM described by platform
+firmware or a device driver. On ACPI based systems the platform firmware
+conveys persistent memory resource via the ACPI NFIT "NVDIMM Firmware
+Interface Table" in ACPI 6. While the LIBNVDIMM subsystem implementation
+is generic and supports pre-NFIT platforms, it was guided by the
+superset of capabilities need to support this ACPI 6 definition for
+NVDIMM resources. The original implementation supported the
+block-window-aperture capability described in the NFIT, but that support
+has since been abandoned and never shipped in a product.
 
 Supporting Documents
 --------------------
@@ -125,107 +116,38 @@ Git Trees
 ---------
 
 LIBNVDIMM:
-	https://git.kernel.org/cgit/linux/kernel/git/djbw/nvdimm.git
+	https://git.kernel.org/cgit/linux/kernel/git/nvdimm/nvdimm.git
 LIBNDCTL:
 	https://github.com/pmem/ndctl.git
-PMEM:
-	https://github.com/01org/prd
 
 
-LIBNVDIMM PMEM and BLK
-======================
+LIBNVDIMM PMEM
+==============
 
 Prior to the arrival of the NFIT, non-volatile memory was described to a
 system in various ad-hoc ways.  Usually only the bare minimum was
 provided, namely, a single system-physical-address range where writes
 are expected to be durable after a system power loss.  Now, the NFIT
 specification standardizes not only the description of PMEM, but also
-BLK and platform message-passing entry points for control and
-configuration.
-
-For each NVDIMM access method (PMEM, BLK), LIBNVDIMM provides a block
-device driver:
-
-    1. PMEM (nd_pmem.ko): Drives a system-physical-address range.  This
-       range is contiguous in system memory and may be interleaved (hardware
-       memory controller striped) across multiple DIMMs.  When interleaved the
-       platform may optionally provide details of which DIMMs are participating
-       in the interleave.
-
-       Note that while LIBNVDIMM describes system-physical-address ranges that may
-       alias with BLK access as ND_NAMESPACE_PMEM ranges and those without
-       alias as ND_NAMESPACE_IO ranges, to the nd_pmem driver there is no
-       distinction.  The different device-types are an implementation detail
-       that userspace can exploit to implement policies like "only interface
-       with address ranges from certain DIMMs".  It is worth noting that when
-       aliasing is present and a DIMM lacks a label, then no block device can
-       be created by default as userspace needs to do at least one allocation
-       of DPA to the PMEM range.  In contrast ND_NAMESPACE_IO ranges, once
-       registered, can be immediately attached to nd_pmem.
-
-    2. BLK (nd_blk.ko): This driver performs I/O using a set of platform
-       defined apertures.  A set of apertures will access just one DIMM.
-       Multiple windows (apertures) allow multiple concurrent accesses, much like
-       tagged-command-queuing, and would likely be used by different threads or
-       different CPUs.
-
-       The NFIT specification defines a standard format for a BLK-aperture, but
-       the spec also allows for vendor specific layouts, and non-NFIT BLK
-       implementations may have other designs for BLK I/O.  For this reason
-       "nd_blk" calls back into platform-specific code to perform the I/O.
-
-       One such implementation is defined in the "Driver Writer's Guide" and "DSM
-       Interface Example".
-
-
-Why BLK?
-========
+platform message-passing entry points for control and configuration.
+
+PMEM (nd_pmem.ko): Drives a system-physical-address range.  This range is
+contiguous in system memory and may be interleaved (hardware memory controller
+striped) across multiple DIMMs.  When interleaved the platform may optionally
+provide details of which DIMMs are participating in the interleave.
+
+It is worth noting that when the labeling capability is detected (a EFI
+namespace label index block is found), then no block device is created
+by default as userspace needs to do at least one allocation of DPA to
+the PMEM range.  In contrast ND_NAMESPACE_IO ranges, once registered,
+can be immediately attached to nd_pmem. This latter mode is called
+label-less or "legacy".
+
+PMEM-REGIONs, Atomic Sectors, and DAX
+-------------------------------------
 
-While PMEM provides direct byte-addressable CPU-load/store access to
-NVDIMM storage, it does not provide the best system RAS (recovery,
-availability, and serviceability) model.  An access to a corrupted
-system-physical-address address causes a CPU exception while an access
-to a corrupted address through an BLK-aperture causes that block window
-to raise an error status in a register.  The latter is more aligned with
-the standard error model that host-bus-adapter attached disks present.
-
-Also, if an administrator ever wants to replace a memory it is easier to
-service a system at DIMM module boundaries.  Compare this to PMEM where
-data could be interleaved in an opaque hardware specific manner across
-several DIMMs.
-
-PMEM vs BLK
------------
-
-BLK-apertures solve these RAS problems, but their presence is also the
-major contributing factor to the complexity of the ND subsystem.  They
-complicate the implementation because PMEM and BLK alias in DPA space.
-Any given DIMM's DPA-range may contribute to one or more
-system-physical-address sets of interleaved DIMMs, *and* may also be
-accessed in its entirety through its BLK-aperture.  Accessing a DPA
-through a system-physical-address while simultaneously accessing the
-same DPA through a BLK-aperture has undefined results.  For this reason,
-DIMMs with this dual interface configuration include a DSM function to
-store/retrieve a LABEL.  The LABEL effectively partitions the DPA-space
-into exclusive system-physical-address and BLK-aperture accessible
-regions.  For simplicity a DIMM is allowed a PMEM "region" per each
-interleave set in which it is a member.  The remaining DPA space can be
-carved into an arbitrary number of BLK devices with discontiguous
-extents.
-
-BLK-REGIONs, PMEM-REGIONs, Atomic Sectors, and DAX
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-One of the few
-reasons to allow multiple BLK namespaces per REGION is so that each
-BLK-namespace can be configured with a BTT with unique atomic sector
-sizes.  While a PMEM device can host a BTT the LABEL specification does
-not provide for a sector size to be specified for a PMEM namespace.
-
-This is due to the expectation that the primary usage model for PMEM is
-via DAX, and the BTT is incompatible with DAX.  However, for the cases
-where an application or filesystem still needs atomic sector update
-guarantees it can register a BTT on a PMEM device or partition.  See
+For the cases where an application or filesystem still needs atomic sector
+update guarantees it can register a BTT on a PMEM device or partition.  See
 LIBNVDIMM/NDCTL: Block Translation Table "btt"
 
 
@@ -236,51 +158,40 @@ For the remainder of this document the following diagram will be
 referenced for any example sysfs layouts::
 
 
-                               (a)               (b)           DIMM   BLK-REGION
+                               (a)               (b)           DIMM
             +-------------------+--------+--------+--------+
-  +------+  |       pm0.0       | blk2.0 | pm1.0  | blk2.1 |    0      region2
+  +------+  |       pm0.0       |  free  | pm1.0  |  free  |    0
   | imc0 +--+- - - region0- - - +--------+        +--------+
-  +--+---+  |       pm0.0       | blk3.0 | pm1.0  | blk3.1 |    1      region3
+  +--+---+  |       pm0.0       |  free  | pm1.0  |  free  |    1
      |      +-------------------+--------v        v--------+
   +--+---+                               |                 |
   | cpu0 |                                     region1
   +--+---+                               |                 |
      |      +----------------------------^        ^--------+
-  +--+---+  |           blk4.0           | pm1.0  | blk4.0 |    2      region4
+  +--+---+  |           free             | pm1.0  |  free  |    2
   | imc1 +--+----------------------------|        +--------+
-  +------+  |           blk5.0           | pm1.0  | blk5.0 |    3      region5
+  +------+  |           free             | pm1.0  |  free  |    3
             +----------------------------+--------+--------+
 
 In this platform we have four DIMMs and two memory controllers in one
-socket.  Each unique interface (BLK or PMEM) to DPA space is identified
-by a region device with a dynamically assigned id (REGION0 - REGION5).
+socket.  Each PMEM interleave set is identified by a region device with
+a dynamically assigned id.
 
     1. The first portion of DIMM0 and DIMM1 are interleaved as REGION0. A
        single PMEM namespace is created in the REGION0-SPA-range that spans most
        of DIMM0 and DIMM1 with a user-specified name of "pm0.0". Some of that
-       interleaved system-physical-address range is reclaimed as BLK-aperture
-       accessed space starting at DPA-offset (a) into each DIMM.  In that
-       reclaimed space we create two BLK-aperture "namespaces" from REGION2 and
-       REGION3 where "blk2.0" and "blk3.0" are just human readable names that
-       could be set to any user-desired name in the LABEL.
+       interleaved system-physical-address range is left free for
+       another PMEM namespace to be defined.
 
     2. In the last portion of DIMM0 and DIMM1 we have an interleaved
        system-physical-address range, REGION1, that spans those two DIMMs as
        well as DIMM2 and DIMM3.  Some of REGION1 is allocated to a PMEM namespace
-       named "pm1.0", the rest is reclaimed in 4 BLK-aperture namespaces (for
-       each DIMM in the interleave set), "blk2.1", "blk3.1", "blk4.0", and
-       "blk5.0".
-
-    3. The portion of DIMM2 and DIMM3 that do not participate in the REGION1
-       interleaved system-physical-address range (i.e. the DPA address past
-       offset (b) are also included in the "blk4.0" and "blk5.0" namespaces.
-       Note, that this example shows that BLK-aperture namespaces don't need to
-       be contiguous in DPA-space.
+       named "pm1.0".
 
     This bus is provided by the kernel under the device
     /sys/devices/platform/nfit_test.0 when the nfit_test.ko module from
-    tools/testing/nvdimm is loaded.  This not only test LIBNVDIMM but the
-    acpi_nfit.ko driver as well.
+    tools/testing/nvdimm is loaded. This module is a unit test for
+    LIBNVDIMM and the  acpi_nfit.ko driver.
 
 
 LIBNVDIMM Kernel Device Model and LIBNDCTL Userspace API
@@ -469,17 +380,14 @@ identified by an "nfit_handle" a 32-bit value where:
 LIBNVDIMM/LIBNDCTL: Region
 --------------------------
 
-A generic REGION device is registered for each PMEM range or BLK-aperture
-set.  Per the example there are 6 regions: 2 PMEM and 4 BLK-aperture
-sets on the "nfit_test.0" bus.  The primary role of regions are to be a
-container of "mappings".  A mapping is a tuple of <DIMM,
-DPA-start-offset, length>.
+A generic REGION device is registered for each PMEM interleave-set /
+range. Per the example there are 2 PMEM regions on the "nfit_test.0"
+bus. The primary role of regions are to be a container of "mappings".  A
+mapping is a tuple of <DIMM, DPA-start-offset, length>.
 
-LIBNVDIMM provides a built-in driver for these REGION devices.  This driver
-is responsible for reconciling the aliased DPA mappings across all
-regions, parsing the LABEL, if present, and then emitting NAMESPACE
-devices with the resolved/exclusive DPA-boundaries for the nd_pmem or
-nd_blk device driver to consume.
+LIBNVDIMM provides a built-in driver for REGION devices.  This driver
+is responsible for all parsing LABELs, if present, and then emitting NAMESPACE
+devices for the nd_pmem driver to consume.
 
 In addition to the generic attributes of "mapping"s, "interleave_ways"
 and "size" the REGION device also exports some convenience attributes.
@@ -493,8 +401,6 @@ LIBNVDIMM: region::
 
 	struct nd_region *nvdimm_pmem_region_create(struct nvdimm_bus *nvdimm_bus,
 			struct nd_region_desc *ndr_desc);
-	struct nd_region *nvdimm_blk_region_create(struct nvdimm_bus *nvdimm_bus,
-			struct nd_region_desc *ndr_desc);
 
 ::
 
@@ -527,8 +433,9 @@ LIBNDCTL: region enumeration example
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Sample region retrieval routines based on NFIT-unique data like
-"spa_index" (interleave set id) for PMEM and "nfit_handle" (dimm id) for
-BLK::
+"spa_index" (interleave set id).
+
+::
 
 	static struct ndctl_region *get_pmem_region_by_spa_index(struct ndctl_bus *bus,
 			unsigned int spa_index)
@@ -544,139 +451,23 @@ BLK::
 		return NULL;
 	}
 
-	static struct ndctl_region *get_blk_region_by_dimm_handle(struct ndctl_bus *bus,
-			unsigned int handle)
-	{
-		struct ndctl_region *region;
-
-		ndctl_region_foreach(bus, region) {
-			struct ndctl_mapping *map;
-
-			if (ndctl_region_get_type(region) != ND_DEVICE_REGION_BLOCK)
-				continue;
-			ndctl_mapping_foreach(region, map) {
-				struct ndctl_dimm *dimm = ndctl_mapping_get_dimm(map);
-
-				if (ndctl_dimm_get_handle(dimm) == handle)
-					return region;
-			}
-		}
-		return NULL;
-	}
-
-
-Why Not Encode the Region Type into the Region Name?
-----------------------------------------------------
-
-At first glance it seems since NFIT defines just PMEM and BLK interface
-types that we should simply name REGION devices with something derived
-from those type names.  However, the ND subsystem explicitly keeps the
-REGION name generic and expects userspace to always consider the
-region-attributes for four reasons:
-
-    1. There are already more than two REGION and "namespace" types.  For
-       PMEM there are two subtypes.  As mentioned previously we have PMEM where
-       the constituent DIMM devices are known and anonymous PMEM.  For BLK
-       regions the NFIT specification already anticipates vendor specific
-       implementations.  The exact distinction of what a region contains is in
-       the region-attributes not the region-name or the region-devtype.
-
-    2. A region with zero child-namespaces is a possible configuration.  For
-       example, the NFIT allows for a DCR to be published without a
-       corresponding BLK-aperture.  This equates to a DIMM that can only accept
-       control/configuration messages, but no i/o through a descendant block
-       device.  Again, this "type" is advertised in the attributes ('mappings'
-       == 0) and the name does not tell you much.
-
-    3. What if a third major interface type arises in the future?  Outside
-       of vendor specific implementations, it's not difficult to envision a
-       third class of interface type beyond BLK and PMEM.  With a generic name
-       for the REGION level of the device-hierarchy old userspace
-       implementations can still make sense of new kernel advertised
-       region-types.  Userspace can always rely on the generic region
-       attributes like "mappings", "size", etc and the expected child devices
-       named "namespace".  This generic format of the device-model hierarchy
-       allows the LIBNVDIMM and LIBNDCTL implementations to be more uniform and
-       future-proof.
-
-    4. There are more robust mechanisms for determining the major type of a
-       region than a device name.  See the next section, How Do I Determine the
-       Major Type of a Region?
-
-How Do I Determine the Major Type of a Region?
-----------------------------------------------
-
-Outside of the blanket recommendation of "use libndctl", or simply
-looking at the kernel header (/usr/include/linux/ndctl.h) to decode the
-"nstype" integer attribute, here are some other options.
-
-1. module alias lookup
-^^^^^^^^^^^^^^^^^^^^^^
-
-    The whole point of region/namespace device type differentiation is to
-    decide which block-device driver will attach to a given LIBNVDIMM namespace.
-    One can simply use the modalias to lookup the resulting module.  It's
-    important to note that this method is robust in the presence of a
-    vendor-specific driver down the road.  If a vendor-specific
-    implementation wants to supplant the standard nd_blk driver it can with
-    minimal impact to the rest of LIBNVDIMM.
-
-    In fact, a vendor may also want to have a vendor-specific region-driver
-    (outside of nd_region).  For example, if a vendor defined its own LABEL
-    format it would need its own region driver to parse that LABEL and emit
-    the resulting namespaces.  The output from module resolution is more
-    accurate than a region-name or region-devtype.
-
-2. udev
-^^^^^^^
-
-    The kernel "devtype" is registered in the udev database::
-
-	# udevadm info --path=/devices/platform/nfit_test.0/ndbus0/region0
-	P: /devices/platform/nfit_test.0/ndbus0/region0
-	E: DEVPATH=/devices/platform/nfit_test.0/ndbus0/region0
-	E: DEVTYPE=nd_pmem
-	E: MODALIAS=nd:t2
-	E: SUBSYSTEM=nd
-
-	# udevadm info --path=/devices/platform/nfit_test.0/ndbus0/region4
-	P: /devices/platform/nfit_test.0/ndbus0/region4
-	E: DEVPATH=/devices/platform/nfit_test.0/ndbus0/region4
-	E: DEVTYPE=nd_blk
-	E: MODALIAS=nd:t3
-	E: SUBSYSTEM=nd
-
-    ...and is available as a region attribute, but keep in mind that the
-    "devtype" does not indicate sub-type variations and scripts should
-    really be understanding the other attributes.
-
-3. type specific attributes
-^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-    As it currently stands a BLK-aperture region will never have a
-    "nfit/spa_index" attribute, but neither will a non-NFIT PMEM region.  A
-    BLK region with a "mappings" value of 0 is, as mentioned above, a DIMM
-    that does not allow I/O.  A PMEM region with a "mappings" value of zero
-    is a simple system-physical-address range.
-
 
 LIBNVDIMM/LIBNDCTL: Namespace
 -----------------------------
 
-A REGION, after resolving DPA aliasing and LABEL specified boundaries,
-surfaces one or more "namespace" devices.  The arrival of a "namespace"
-device currently triggers either the nd_blk or nd_pmem driver to load
-and register a disk/block device.
+A REGION, after resolving DPA aliasing and LABEL specified boundaries, surfaces
+one or more "namespace" devices.  The arrival of a "namespace" device currently
+triggers the nd_pmem driver to load and register a disk/block device.
 
 LIBNVDIMM: namespace
 ^^^^^^^^^^^^^^^^^^^^
 
-Here is a sample layout from the three major types of NAMESPACE where
-namespace0.0 represents DIMM-info-backed PMEM (note that it has a 'uuid'
-attribute), namespace2.0 represents a BLK namespace (note it has a
-'sector_size' attribute) that, and namespace6.0 represents an anonymous
-PMEM namespace (note that has no 'uuid' attribute due to not support a
-LABEL)::
+Here is a sample layout from the 2 major types of NAMESPACE where namespace0.0
+represents DIMM-info-backed PMEM (note that it has a 'uuid' attribute), and
+namespace1.0 represents an anonymous PMEM namespace (note that has no 'uuid'
+attribute due to not support a LABEL)
+
+::
 
 	/sys/devices/platform/nfit_test.0/ndbus0/region0/namespace0.0
 	|-- alt_name
@@ -691,20 +482,7 @@ LABEL)::
 	|-- type
 	|-- uevent
 	`-- uuid
-	/sys/devices/platform/nfit_test.0/ndbus0/region2/namespace2.0
-	|-- alt_name
-	|-- devtype
-	|-- dpa_extents
-	|-- force_raw
-	|-- modalias
-	|-- numa_node
-	|-- sector_size
-	|-- size
-	|-- subsystem -> ../../../../../../bus/nd
-	|-- type
-	|-- uevent
-	`-- uuid
-	/sys/devices/platform/nfit_test.1/ndbus1/region6/namespace6.0
+	/sys/devices/platform/nfit_test.1/ndbus1/region1/namespace1.0
 	|-- block
 	|   `-- pmem0
 	|-- devtype
@@ -786,9 +564,9 @@ Why the Term "namespace"?
 LIBNVDIMM/LIBNDCTL: Block Translation Table "btt"
 -------------------------------------------------
 
-A BTT (design document: https://pmem.io/2014/09/23/btt.html) is a stacked
-block device driver that fronts either the whole block device or a
-partition of a block device emitted by either a PMEM or BLK NAMESPACE.
+A BTT (design document: https://pmem.io/2014/09/23/btt.html) is a
+personality driver for a namespace that fronts entire namespace as an
+'address abstraction'.
 
 LIBNVDIMM: btt layout
 ^^^^^^^^^^^^^^^^^^^^^
@@ -815,7 +593,9 @@ LIBNDCTL: btt creation example
 Similar to namespaces an idle BTT device is automatically created per
 region.  Each time this "seed" btt device is configured and enabled a new
 seed is created.  Creating a BTT configuration involves two steps of
-finding and idle BTT and assigning it to consume a PMEM or BLK namespace::
+finding and idle BTT and assigning it to consume a namespace.
+
+::
 
 	static struct ndctl_btt *get_idle_btt(struct ndctl_region *region)
 	{
@@ -863,25 +643,15 @@ For the given example above, here is the view of the objects as seen by the
 LIBNDCTL API::
 
               +---+
-              |CTX|    +---------+   +--------------+  +---------------+
-              +-+-+  +-> REGION0 +---> NAMESPACE0.0 +--> PMEM8 "pm0.0" |
-                |    | +---------+   +--------------+  +---------------+
-  +-------+     |    | +---------+   +--------------+  +---------------+
-  | DIMM0 <-+   |    +-> REGION1 +---> NAMESPACE1.0 +--> PMEM6 "pm1.0" |
-  +-------+ |   |    | +---------+   +--------------+  +---------------+
+              |CTX|
+              +-+-+
+                |
+  +-------+     |
+  | DIMM0 <-+   |      +---------+   +--------------+  +---------------+
+  +-------+ |   |    +-> REGION0 +---> NAMESPACE0.0 +--> PMEM8 "pm0.0" |
   | DIMM1 <-+ +-v--+ | +---------+   +--------------+  +---------------+
-  +-------+ +-+BUS0+---> REGION2 +-+-> NAMESPACE2.0 +--> ND6  "blk2.0" |
-  | DIMM2 <-+ +----+ | +---------+ | +--------------+  +----------------------+
-  +-------+ |        |             +-> NAMESPACE2.1 +--> ND5  "blk2.1" | BTT2 |
-  | DIMM3 <-+        |               +--------------+  +----------------------+
-  +-------+          | +---------+   +--------------+  +---------------+
-                     +-> REGION3 +-+-> NAMESPACE3.0 +--> ND4  "blk3.0" |
-                     | +---------+ | +--------------+  +----------------------+
-                     |             +-> NAMESPACE3.1 +--> ND3  "blk3.1" | BTT1 |
-                     |               +--------------+  +----------------------+
-                     | +---------+   +--------------+  +---------------+
-                     +-> REGION4 +---> NAMESPACE4.0 +--> ND2  "blk4.0" |
-                     | +---------+   +--------------+  +---------------+
-                     | +---------+   +--------------+  +----------------------+
-                     +-> REGION5 +---> NAMESPACE5.0 +--> ND1  "blk5.0" | BTT0 |
-                       +---------+   +--------------+  +---------------+------+
+  +-------+ +-+BUS0+-| +---------+   +--------------+  +----------------------+
+  | DIMM2 <-+ +----+ +-> REGION1 +---> NAMESPACE1.0 +--> PMEM6 "pm1.0" | BTT1 |
+  +-------+ |        | +---------+   +--------------+  +---------------+------+
+  | DIMM3 <-+
+  +-------+