NAME

       daxctl-migrate-device-model - Opt-in to the /sys/bus/dax device-model, allow for
       alternative Device-DAX instance drivers.

SYNOPSIS

       daxctl migrate-device-model

       Arrange for modprobe to disable the dax_pmem_compat, if present, and instead deploy the
       dax_pmem module to convert to the /sys/bus/dax model. Kernel versions prior to v5.1 may
       not support /sys/bus/dax in which case the result of this command is a nop until the
       kernel is updated. The motivation for changing from /sys/class/dax to /sys/bus/dax is to
       allow for alternative drivers for Device-DAX instances, in particular the dax_kmem driver.

       By default device-dax publishes a /dev/daxX.Y character device for userspace to directly
       map performance differentiated memory. This is fine if the memory is to be exclusively
       consumed / managed by userspace. Alternatively an administrator may want the kernel to
       manage the memory, make it available via malloc(), allow for over-provisioning, and / or
       apply kernel-based resource control schemes to the memory. In that case the memory fronted
       by a given Device-DAX instance can be assigned to the dax_kmem driver which arranges for
       the core-kernel memory-management sub-system to assume management of the memory range.

       This behavior is opt-in for consideration of existing applications / scripts that may be
       hard coded to use /sys/class/dax. Fixes have been submitted to applications known to have
       these direct dependencies FIO <http://git.kernel.dk/cgit/fio/commit/?id=b08e7d6b18b4> PMDK
       <https://github.com/pmem/pmdk/commit/91bc8620884e>, however, there may be others and a
       system-owner should be aware of the potential for regression of Device-DAX consuming
       scripts, applications, or older daxctl binaries.

       The modprobe policy established by this utility becomes effective after the next reboot,
       or after all DAX related modules have been removed and re-loaded with "udevadm trigger"

COPYRIGHT

       Copyright © 2016 - 2022, Intel Corporation. License GPLv2: GNU GPL version 2
       http://gnu.org/licenses/gpl.html. This is free software: you are free to change and
       redistribute it. There is NO WARRANTY, to the extent permitted by law.