1# SPDX-License-Identifier: GPL-2.0-only 2config DAX_DRIVER 3 select DAX 4 bool 5 6menuconfig DAX 7 tristate "DAX: direct access to differentiated memory" 8 select SRCU 9 default m if NVDIMM_DAX 10 11if DAX 12 13config DEV_DAX 14 tristate "Device DAX: direct access mapping device" 15 depends on TRANSPARENT_HUGEPAGE 16 help 17 Support raw access to differentiated (persistence, bandwidth, 18 latency...) memory via an mmap(2) capable character 19 device. Platform firmware or a device driver may identify a 20 platform memory resource that is differentiated from the 21 baseline memory pool. Mappings of a /dev/daxX.Y device impose 22 restrictions that make the mapping behavior deterministic. 23 24config DEV_DAX_PMEM 25 tristate "PMEM DAX: direct access to persistent memory" 26 depends on LIBNVDIMM && NVDIMM_DAX && DEV_DAX 27 default DEV_DAX 28 help 29 Support raw access to persistent memory. Note that this 30 driver consumes memory ranges allocated and exported by the 31 libnvdimm sub-system. 32 33 Say M if unsure 34 35config DEV_DAX_HMEM 36 tristate "HMEM DAX: direct access to 'specific purpose' memory" 37 depends on EFI_SOFT_RESERVE 38 select NUMA_KEEP_MEMINFO if (NUMA && X86) 39 default DEV_DAX 40 help 41 EFI 2.8 platforms, and others, may advertise 'specific purpose' 42 memory. For example, a high bandwidth memory pool. The 43 indication from platform firmware is meant to reserve the 44 memory from typical usage by default. This driver creates 45 device-dax instances for these memory ranges, and that also 46 enables the possibility to assign them to the DEV_DAX_KMEM 47 driver to override the reservation and add them to kernel 48 "System RAM" pool. 49 50 Say M if unsure. 51 52config DEV_DAX_HMEM_DEVICES 53 depends on DEV_DAX_HMEM && DAX=y 54 def_bool y 55 56config DEV_DAX_KMEM 57 tristate "KMEM DAX: volatile-use of persistent memory" 58 default DEV_DAX 59 depends on DEV_DAX 60 depends on MEMORY_HOTPLUG # for add_memory() and friends 61 help 62 Support access to persistent, or other performance 63 differentiated memory as if it were System RAM. This allows 64 easier use of persistent memory by unmodified applications, or 65 adds core kernel memory services to heterogeneous memory types 66 (HMEM) marked "reserved" by platform firmware. 67 68 To use this feature, a DAX device must be unbound from the 69 device_dax driver and bound to this kmem driver on each boot. 70 71 Say N if unsure. 72 73config DEV_DAX_PMEM_COMPAT 74 tristate "PMEM DAX: support the deprecated /sys/class/dax interface" 75 depends on m && DEV_DAX_PMEM=m 76 default DEV_DAX_PMEM 77 help 78 Older versions of the libdaxctl library expect to find all 79 device-dax instances under /sys/class/dax. If libdaxctl in 80 your distribution is older than v58 say M, otherwise say N. 81 82endif 83