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authorDan Williams <dan.j.williams@intel.com>2017-07-16 13:51:53 -0700
committerDan Williams <dan.j.williams@intel.com>2019-01-06 21:41:57 -0800
commit730926c3b0998943654019f00296cf8e3b02277e (patch)
tree9bdff0b62f4a020427144de5b703048bfb1f7c16 /Documentation/ABI/obsolete
parentd200781ef237a354d918ceff5cee350d88a93d42 (diff)
device-dax: Add /sys/class/dax backwards compatibility
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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+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/