1DAXCTL-MIGRATE-DEV(1)            daxctl Manual           DAXCTL-MIGRATE-DEV(1)
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NAME

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

10       daxctl migrate-device-model
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12       Arrange for modprobe to disable the dax_pmem_compat, if present, and
13       instead deploy the dax_pmem module to convert to the /sys/bus/dax
14       model. Kernel versions prior to v5.1 may not support /sys/bus/dax in
15       which case the result of this command is a nop until the kernel is
16       updated. The motivation for changing from /sys/class/dax to
17       /sys/bus/dax is to allow for alternative drivers for Device-DAX
18       instances, in particular the dax_kmem driver.
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20       By default device-dax publishes a /dev/daxX.Y character device for
21       userspace to directly map performance differentiated memory. This is
22       fine if the memory is to be exclusively consumed / managed by
23       userspace. Alternatively an administrator may want the kernel to manage
24       the memory, make it available via malloc(), allow for
25       over-provisioning, and / or apply kernel-based resource control schemes
26       to the memory. In that case the memory fronted by a given Device-DAX
27       instance can be assigned to the dax_kmem driver which arranges for the
28       core-kernel memory-management sub-system to assume management of the
29       memory range.
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31       This behavior is opt-in for consideration of existing applications /
32       scripts that may be hard coded to use /sys/class/dax. Fixes have been
33       submitted to applications known to have these direct dependencies
34       FIO[1] PMDK[2], however, there may be others and a system-owner should
35       be aware of the potential for regression of Device-DAX consuming
36       scripts, applications, or older daxctl binaries.
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38       The modprobe policy established by this utility becomes effective after
39       the next reboot, or after all DAX related modules have been removed and
40       re-loaded with "udevadm trigger"
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43       Copyright © 2016 - 2020, Intel Corporation. License GPLv2: GNU GPL
44       version 2 http://gnu.org/licenses/gpl.html. This is free software: you
45       are free to change and redistribute it. There is NO WARRANTY, to the
46       extent permitted by law.
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NOTES

49        1. FIO
50           http://git.kernel.dk/cgit/fio/commit/?id=b08e7d6b18b4
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52        2. PMDK
53           https://github.com/pmem/pmdk/commit/91bc8620884e
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57daxctl 71.1                       07/22/2021             DAXCTL-MIGRATE-DEV(1)
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