Clone this repo:
  1. 16f4575 ndctl: release v79 by Vishal Verma · 7 weeks ago main pending v79
  2. add0c37 Build: Fix deprecated str.format() usage by Dan Williams · 7 weeks ago
  3. 7c8c993 cxl/test: use max_available_extent in cxl-destroy-region by Alison Schofield · 8 weeks ago
  4. f533bd7 daxctl/device.c: Fix error propagation in do_xaction_device() by Vishal Verma · 10 weeks ago
  5. d78f57e daxctl/device.c: Handle special case of destroying daxX.0 by Vishal Verma · 10 weeks ago


Utility library for managing the libnvdimm (non-volatile memory device) sub-system in the Linux kernel


meson setup build;
meson compile -C build;

Optionally, to install:

meson install -C build

There are a number of packages required for the build steps that may not be installed by default. For information about the required packages, see the “BuildRequires:” lines in


See the latest documentation for the NVDIMM kernel sub-system here:

A getting started guide is also available on the nvdimm wiki:

Unit Tests

The unit tests run by meson test require the nfit_test.ko module to be loaded. To build and install nfit_test.ko:

  1. Obtain the kernel source. For example,
    git clone -b libnvdimm-for-next git://

  2. Skip to step 3 if the kernel version is >= v4.8. Otherwise, for kernel versions < v4.8, configure the kernel to make some memory available to CMA (contiguous memory allocator). This will be used to emulate DAX.


    cma=200M on the kernel command line.

  3. Compile the libnvdimm sub-system as a module, make sure “zone device” memory is enabled, and enable the btt, pfn, and dax features of the sub-system:

  4. Build and install the unit test enabled libnvdimm modules in the following order. The unit test modules need to be in place prior to the depmod that runs during the final modules_install

    make M=tools/testing/nvdimm
    sudo make M=tools/testing/nvdimm modules_install
    sudo make modules_install
  5. CXL test

    The unit tests will also run CXL tests by default. In order to make these work, we need to install the cxl_test.ko as well.

    Obtain the CXL kernel source(optional). For example, git clone -b pending git://

    Enable CXL-related kernel configuration options.

  6. Install cxl_test and related mock modules.

    make M=tools/testing/cxl
    sudo make M=tools/testing/cxl modules_install
    sudo make modules_install
  7. Now run meson test -C build in the ndctl source directory, or ndctl test, if ndctl was built with -Dtest=enabled as a configuration option to meson.

  8. To run the ‘destructive’ set of tests that may clobber existing pmem configurations and data, configure meson with the destructive option after the meson setup step:

    meson configure -Dtest=enabled -Ddestructive=enabled build;


The unit tests will validate that the environment is set up correctly before they try to run. If the platform is misconfigured, i.e. the unit test modules are not available, or the test versions of the modules are superseded by the “in-tree/production” version of the modules meson test will skip tests and report a message like the following in build/meson-logs/testlog.txt

SKIP: libndctl
test/init: nfit_test_init: nfit.ko: appears to be production version: /lib/modules/4.8.8-200.fc24.x86_64/kernel/drivers/acpi/nfit/nfit.ko.xz
__ndctl_test_skip: explicit skip test_libndctl:2684
nfit_test unavailable skipping tests

If the unit test modules are indeed available in the modules ‘extra’ directory the default depmod policy can be overridden by adding a file to /etc/depmod.d with the following contents:

override nfit * extra
override device_dax * extra
override dax_pmem * extra
override dax_pmem_core * extra
override dax_pmem_compat * extra
override libnvdimm * extra
override nd_btt * extra
override nd_e820 * extra
override nd_pmem * extra

The nfit_test module emulates pmem with memory allocated via vmalloc(). One of the side effects is that this breaks ‘physically contiguous’ assumptions in the driver. Use the '--align=4K option to ‘ndctl create-namespace’ to avoid these corner case scenarios.