# SPDX-License-Identifier: GPL-2.0-only config DAX_DRIVER select DAX bool menuconfig DAX tristate "DAX: direct access to differentiated memory" select SRCU default m if NVDIMM_DAX if DAX config DEV_DAX tristate "Device DAX: direct access mapping device" depends on TRANSPARENT_HUGEPAGE help Support raw access to differentiated (persistence, bandwidth, latency...) memory via an mmap(2) capable character device. Platform firmware or a device driver may identify a platform memory resource that is differentiated from the baseline memory pool. Mappings of a /dev/daxX.Y device impose restrictions that make the mapping behavior deterministic. config DEV_DAX_PMEM tristate "PMEM DAX: direct access to persistent memory" depends on LIBNVDIMM && NVDIMM_DAX && DEV_DAX default DEV_DAX help Support raw access to persistent memory. Note that this driver consumes memory ranges allocated and exported by the libnvdimm sub-system. Say M if unsure config DEV_DAX_HMEM tristate "HMEM DAX: direct access to 'specific purpose' memory" depends on EFI_SOFT_RESERVE default DEV_DAX help EFI 2.8 platforms, and others, may advertise 'specific purpose' memory. For example, a high bandwidth memory pool. The indication from platform firmware is meant to reserve the memory from typical usage by default. This driver creates device-dax instances for these memory ranges, and that also enables the possibility to assign them to the DEV_DAX_KMEM driver to override the reservation and add them to kernel "System RAM" pool. Say M if unsure. config DEV_DAX_KMEM tristate "KMEM DAX: volatile-use of persistent memory" default DEV_DAX depends on DEV_DAX depends on MEMORY_HOTPLUG # for add_memory() and friends help Support access to persistent, or other performance differentiated memory as if it were System RAM. This allows easier use of persistent memory by unmodified applications, or adds core kernel memory services to heterogeneous memory types (HMEM) marked "reserved" by platform firmware. To use this feature, a DAX device must be unbound from the device_dax driver and bound to this kmem driver on each boot. Say N if unsure. config DEV_DAX_PMEM_COMPAT tristate "PMEM DAX: support the deprecated /sys/class/dax interface" depends on m && DEV_DAX_PMEM=m default DEV_DAX_PMEM help Older versions of the libdaxctl library expect to find all device-dax instances under /sys/class/dax. If libdaxctl in your distribution is older than v58 say M, otherwise say N. endif