Prompted by the review of "[PATCH 0/9] Allow persistent memory to be used like normal RAM" [1] introduce a new bus / device-driver-model for device-dax. Currently device-dax instances result from attaching an nvdimm namespace device to the dax_pmem driver. These instances are registered with the /sys/class/dax sub-system. With the expectation that platforms will describe performance differentiated memory [2] for ranges other than persistent memory (pmem) a new device-model is needed. Arrange for dax_pmem to be one of potentially several drivers that know how to discover differentiated memory and register a device instance on the dax bus. The expectation is that, by default, this device is consumed by the typical device-dax driver that will expose the range through a /dev/daxX.Y character device. Optionally other drivers can consume the dax device instance. For example, the kmem driver [1] can attach to device-dax device instance to hot-add the related memory range to the core page-allocator. Going forward, provider drivers outside of dax_pmem can be created to register other memories with unique performance properties. Since /sys/class/dax is a released ABI, a compat driver is provided so that distros can opt-in to the new bus based ABI. The /sys/class/dax interface is then deprecated and scheduled to be removed. [1]: https://lkml.org/lkml/2018/10/23/9 [2]: Section 5.2.27 Heterogeneous Memory Attribute Table (HMAT) http://www.uefi.org/sites/default/files/resources/ACPI%206_2_A_Sept29.pdf --- Dan Williams (8): device-dax: Kill dax_region ida device-dax: Kill dax_region base device-dax: Remove multi-resource infrastructure device-dax: Start defining a dax bus model device-dax: Introduce bus + driver model device-dax: Move resource pinning+mapping into the common driver device-dax: Add support for a dax override driver device-dax: Add /sys/class/dax backwards compatibility Documentation/ABI/obsolete/sysfs-class-dax | 22 + drivers/dax/Kconfig | 12 + drivers/dax/Makefile | 5 drivers/dax/bus.c | 449 ++++++++++++++++++++++++++++ drivers/dax/bus.h | 60 ++++ drivers/dax/dax-private.h | 30 +- drivers/dax/dax.h | 18 - drivers/dax/device-dax.h | 25 -- drivers/dax/device.c | 365 +++++------------------ drivers/dax/pmem.c | 161 ---------- drivers/dax/pmem/Makefile | 7 drivers/dax/pmem/compat.c | 73 +++++ drivers/dax/pmem/core.c | 69 ++++ drivers/dax/pmem/pmem.c | 40 ++ drivers/dax/super.c | 41 ++- tools/testing/nvdimm/Kbuild | 7 tools/testing/nvdimm/dax-dev.c | 16 - 17 files changed, 880 insertions(+), 520 deletions(-) create mode 100644 Documentation/ABI/obsolete/sysfs-class-dax create mode 100644 drivers/dax/bus.c create mode 100644 drivers/dax/bus.h delete mode 100644 drivers/dax/dax.h delete mode 100644 drivers/dax/device-dax.h delete mode 100644 drivers/dax/pmem.c create mode 100644 drivers/dax/pmem/Makefile create mode 100644 drivers/dax/pmem/compat.c create mode 100644 drivers/dax/pmem/core.c create mode 100644 drivers/dax/pmem/pmem.c
