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1# SPDX-License-Identifier: GPL-2.0-only2menuconfig DAX3 tristate "DAX: direct access to differentiated memory"4 default m if NVDIMM_DAX5 6if DAX7 8config DEV_DAX9 tristate "Device DAX: direct access mapping device"10 depends on TRANSPARENT_HUGEPAGE11 help12 Support raw access to differentiated (persistence, bandwidth,13 latency...) memory via an mmap(2) capable character14 device. Platform firmware or a device driver may identify a15 platform memory resource that is differentiated from the16 baseline memory pool. Mappings of a /dev/daxX.Y device impose17 restrictions that make the mapping behavior deterministic.18 19config DEV_DAX_PMEM20 tristate "PMEM DAX: direct access to persistent memory"21 depends on LIBNVDIMM && NVDIMM_DAX && DEV_DAX22 default DEV_DAX23 help24 Support raw access to persistent memory. Note that this25 driver consumes memory ranges allocated and exported by the26 libnvdimm sub-system.27 28 Say M if unsure29 30config DEV_DAX_HMEM31 tristate "HMEM DAX: direct access to 'specific purpose' memory"32 depends on EFI_SOFT_RESERVE33 select NUMA_KEEP_MEMINFO if NUMA_MEMBLKS34 default DEV_DAX35 help36 EFI 2.8 platforms, and others, may advertise 'specific purpose'37 memory. For example, a high bandwidth memory pool. The38 indication from platform firmware is meant to reserve the39 memory from typical usage by default. This driver creates40 device-dax instances for these memory ranges, and that also41 enables the possibility to assign them to the DEV_DAX_KMEM42 driver to override the reservation and add them to kernel43 "System RAM" pool.44 45 Say M if unsure.46 47config DEV_DAX_CXL48 tristate "CXL DAX: direct access to CXL RAM regions"49 depends on CXL_BUS && CXL_REGION && DEV_DAX50 default CXL_REGION && DEV_DAX51 help52 CXL RAM regions are either mapped by platform-firmware53 and published in the initial system-memory map as "System RAM", mapped54 by platform-firmware as "Soft Reserved", or dynamically provisioned55 after boot by the CXL driver. In the latter two cases a device-dax56 instance is created to access that unmapped-by-default address range.57 Per usual it can remain as dedicated access via a device interface, or58 converted to "System RAM" via the dax_kmem facility.59 60config DEV_DAX_HMEM_DEVICES61 depends on DEV_DAX_HMEM && DAX62 def_bool y63 64config DEV_DAX_KMEM65 tristate "KMEM DAX: map dax-devices as System-RAM"66 default DEV_DAX67 depends on DEV_DAX68 depends on MEMORY_HOTPLUG # for add_memory() and friends69 help70 Support access to persistent, or other performance71 differentiated memory as if it were System RAM. This allows72 easier use of persistent memory by unmodified applications, or73 adds core kernel memory services to heterogeneous memory types74 (HMEM) marked "reserved" by platform firmware.75 76 To use this feature, a DAX device must be unbound from the77 device_dax driver and bound to this kmem driver on each boot.78 79 Say N if unsure.80 81endif82