What: /sys/class/dax/
Date: May, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description: Device DAX is the device-centric analogue of Filesystem
DAX (CONFIG_FS_DAX). It allows memory ranges to be
allocated and mapped without need of an intervening file
system. Device DAX is strict, precise and predictable.
Specifically this interface:
1/ Guarantees fault granularity with respect to a given
page size (pte, pmd, or pud) set at configuration time.
2/ Enforces deterministic behavior by being strict about
what fault scenarios are supported.
The /sys/class/dax/ interface enumerates all the
device-dax instances in the system. The ABI is
deprecated and will be removed after 2020. It is
replaced with the DAX bus interface /sys/bus/dax/ where
device-dax instances can be found under
/sys/bus/dax/devices/-
Dan Williams authored
On the expectation that some environments may not upgrade libdaxctl (userspace component that depends on the /sys/class/dax hierarchy), provide a default / legacy dax_pmem_compat driver. The dax_pmem_compat driver implements the original /sys/class/dax sysfs layout rather than /sys/bus/dax. When userspace is upgraded it can blacklist this module and switch to the dax_pmem driver going forward. CONFIG_DEV_DAX_PMEM_COMPAT and supporting code will be deleted according to the dax_pmem entry in Documentation/ABI/obsolete/. Signed-off-by:Dan Williams <dan.j.williams@intel.com>
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