| What: /sys/bus/dax/devices/daxX.Y/align | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RW) Provides a way to specify an alignment for a dax device. | |
| Values allowed are constrained by the physical address ranges | |
| that back the dax device, and also by arch requirements. | |
| What: /sys/bus/dax/devices/daxX.Y/mapping | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (WO) Provides a way to allocate a mapping range under a dax | |
| device. Specified in the format <start>-<end>. | |
| What: /sys/bus/dax/devices/daxX.Y/mapping[0..N]/start | |
| What: /sys/bus/dax/devices/daxX.Y/mapping[0..N]/end | |
| What: /sys/bus/dax/devices/daxX.Y/mapping[0..N]/page_offset | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) A dax device may have multiple constituent discontiguous | |
| address ranges. These are represented by the different | |
| 'mappingX' subdirectories. The 'start' attribute indicates the | |
| start physical address for the given range. The 'end' attribute | |
| indicates the end physical address for the given range. The | |
| 'page_offset' attribute indicates the offset of the current | |
| range in the dax device. | |
| What: /sys/bus/dax/devices/daxX.Y/resource | |
| Date: June, 2019 | |
| KernelVersion: v5.3 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) The resource attribute indicates the starting physical | |
| address of a dax device. In case of a device with multiple | |
| constituent ranges, it indicates the starting address of the | |
| first range. | |
| What: /sys/bus/dax/devices/daxX.Y/size | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RW) The size attribute indicates the total size of a dax | |
| device. For creating subdivided dax devices, or for resizing | |
| an existing device, the new size can be written to this as | |
| part of the reconfiguration process. | |
| What: /sys/bus/dax/devices/daxX.Y/numa_node | |
| Date: November, 2019 | |
| KernelVersion: v5.5 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) If NUMA is enabled and the platform has affinitized the | |
| backing device for this dax device, emit the CPU node | |
| affinity for this device. | |
| What: /sys/bus/dax/devices/daxX.Y/target_node | |
| Date: February, 2019 | |
| KernelVersion: v5.1 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) The target-node attribute is the Linux numa-node that a | |
| device-dax instance may create when it is online. Prior to | |
| being online the device's 'numa_node' property reflects the | |
| closest online cpu node which is the typical expectation of a | |
| device 'numa_node'. Once it is online it becomes its own | |
| distinct numa node. | |
| What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/available_size | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) The available_size attribute tracks available dax region | |
| capacity. This only applies to volatile hmem devices, not pmem | |
| devices, since pmem devices are defined by nvdimm namespace | |
| boundaries. | |
| What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/size | |
| Date: July, 2017 | |
| KernelVersion: v5.1 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) The size attribute indicates the size of a given dax region | |
| in bytes. | |
| What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/align | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) The align attribute indicates alignment of the dax region. | |
| Changes on align may not always be valid, when say certain | |
| mappings were created with 2M and then we switch to 1G. This | |
| validates all ranges against the new value being attempted, post | |
| resizing. | |
| What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/seed | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) The seed device is a concept for dynamic dax regions to be | |
| able to split the region amongst multiple sub-instances. The | |
| seed device, similar to libnvdimm seed devices, is a device | |
| that starts with zero capacity allocated and unbound to a | |
| driver. | |
| What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/create | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RW) The create interface to the dax region provides a way to | |
| create a new unconfigured dax device under the given region, which | |
| can then be configured (with a size etc.) and then probed. | |
| What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/delete | |
| Date: October, 2020 | |
| KernelVersion: v5.10 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (WO) The delete interface for a dax region provides for deletion | |
| of any 0-sized and idle dax devices. | |
| What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/id | |
| Date: July, 2017 | |
| KernelVersion: v5.1 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RO) The id attribute indicates the region id of a dax region. | |
| What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory | |
| Date: January, 2024 | |
| KernelVersion: v6.8 | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RW) Control the memmap_on_memory setting if the dax device | |
| were to be hotplugged as system memory. This determines whether | |
| the 'altmap' for the hotplugged memory will be placed on the | |
| device being hotplugged (memmap_on_memory=1) or if it will be | |
| placed on regular memory (memmap_on_memory=0). This attribute | |
| must be set before the device is handed over to the 'kmem' | |
| driver (i.e. hotplugged into system-ram). Additionally, this | |
| depends on CONFIG_MHP_MEMMAP_ON_MEMORY, and a globally enabled | |
| memmap_on_memory parameter for memory_hotplug. This is | |
| typically set on the kernel command line - | |
| memory_hotplug.memmap_on_memory set to 'true' or 'force'." | |
| What: /sys/bus/dax/devices/daxX.Y/state | |
| Contact: nvdimm@lists.linux.dev | |
| Description: | |
| (RW) Controls the state of the memory region. | |
| Applies to all memory blocks associated with the device. | |
| Only applies to dax_kmem devices. | |
| Reading returns the current state; the writable states mirror | |
| the per-block /sys/devices/system/memory/memoryX/state ABI:: | |
| "unplugged": memory blocks are not present | |
| "online": memory is online, zone chosen by the kernel | |
| "online_kernel": memory is online in ZONE_NORMAL | |
| "online_movable": memory is online in ZONE_MOVABLE | |
| "offline" (memory blocks are present but offline) may also be | |
| reported - this happens when the device is bound while the | |
| auto_online_blocks policy is "offline". It cannot be written, | |
| as it's not useful and creates device destruction races. | |
| A device can only be onlined from the "unplugged" state, so a | |
| device must be returned to "unplugged" before it can be onlined | |
| into a different state. |