| # SPDX-License-Identifier: GPL-2.0-only |
| menuconfig DAX |
| tristate "DAX: direct access to differentiated memory" |
| 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 |
| select NUMA_KEEP_MEMINFO if NUMA_MEMBLKS |
| 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_CXL |
| tristate "CXL DAX: direct access to CXL RAM regions" |
| depends on CXL_BUS && CXL_REGION && DEV_DAX |
| default CXL_REGION && DEV_DAX |
| help |
| CXL RAM regions are either mapped by platform-firmware |
| and published in the initial system-memory map as "System RAM", mapped |
| by platform-firmware as "Soft Reserved", or dynamically provisioned |
| after boot by the CXL driver. In the latter two cases a device-dax |
| instance is created to access that unmapped-by-default address range. |
| Per usual it can remain as dedicated access via a device interface, or |
| converted to "System RAM" via the dax_kmem facility. |
| |
| config DEV_DAX_HMEM_DEVICES |
| depends on DEV_DAX_HMEM && DAX |
| def_bool y |
| |
| config DEV_DAX_KMEM |
| tristate "KMEM DAX: map dax-devices as System-RAM" |
| 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. |
| |
| endif |
