1What: /sys/bus/cxl/flush 2Date: Januarry, 2022 3KernelVersion: v5.18 4Contact: linux-cxl@vger.kernel.org 5Description: 6 (WO) If userspace manually unbinds a port the kernel schedules 7 all descendant memdevs for unbind. Writing '1' to this attribute 8 flushes that work. 9 10 11What: /sys/bus/cxl/devices/memX/firmware_version 12Date: December, 2020 13KernelVersion: v5.12 14Contact: linux-cxl@vger.kernel.org 15Description: 16 (RO) "FW Revision" string as reported by the Identify 17 Memory Device Output Payload in the CXL-2.0 18 specification. 19 20 21What: /sys/bus/cxl/devices/memX/ram/size 22Date: December, 2020 23KernelVersion: v5.12 24Contact: linux-cxl@vger.kernel.org 25Description: 26 (RO) "Volatile Only Capacity" as bytes. Represents the 27 identically named field in the Identify Memory Device Output 28 Payload in the CXL-2.0 specification. 29 30 31What: /sys/bus/cxl/devices/memX/ram/qos_class 32Date: May, 2023 33KernelVersion: v6.8 34Contact: linux-cxl@vger.kernel.org 35Description: 36 (RO) For CXL host platforms that support "QoS Telemmetry" 37 this attribute conveys a comma delimited list of platform 38 specific cookies that identifies a QoS performance class 39 for the volatile partition of the CXL mem device. These 40 class-ids can be compared against a similar "qos_class" 41 published for a root decoder. While it is not required 42 that the endpoints map their local memory-class to a 43 matching platform class, mismatches are not recommended 44 and there are platform specific performance related 45 side-effects that may result. First class-id is displayed. 46 47 48What: /sys/bus/cxl/devices/memX/pmem/size 49Date: December, 2020 50KernelVersion: v5.12 51Contact: linux-cxl@vger.kernel.org 52Description: 53 (RO) "Persistent Only Capacity" as bytes. Represents the 54 identically named field in the Identify Memory Device Output 55 Payload in the CXL-2.0 specification. 56 57 58What: /sys/bus/cxl/devices/memX/pmem/qos_class 59Date: May, 2023 60KernelVersion: v6.8 61Contact: linux-cxl@vger.kernel.org 62Description: 63 (RO) For CXL host platforms that support "QoS Telemmetry" 64 this attribute conveys a comma delimited list of platform 65 specific cookies that identifies a QoS performance class 66 for the persistent partition of the CXL mem device. These 67 class-ids can be compared against a similar "qos_class" 68 published for a root decoder. While it is not required 69 that the endpoints map their local memory-class to a 70 matching platform class, mismatches are not recommended 71 and there are platform specific performance related 72 side-effects that may result. First class-id is displayed. 73 74 75What: /sys/bus/cxl/devices/memX/serial 76Date: January, 2022 77KernelVersion: v5.18 78Contact: linux-cxl@vger.kernel.org 79Description: 80 (RO) 64-bit serial number per the PCIe Device Serial Number 81 capability. Mandatory for CXL devices, see CXL 2.0 8.1.12.2 82 Memory Device PCIe Capabilities and Extended Capabilities. 83 84 85What: /sys/bus/cxl/devices/memX/numa_node 86Date: January, 2022 87KernelVersion: v5.18 88Contact: linux-cxl@vger.kernel.org 89Description: 90 (RO) If NUMA is enabled and the platform has affinitized the 91 host PCI device for this memory device, emit the CPU node 92 affinity for this device. 93 94 95What: /sys/bus/cxl/devices/memX/security/state 96Date: June, 2023 97KernelVersion: v6.5 98Contact: linux-cxl@vger.kernel.org 99Description: 100 (RO) Reading this file will display the CXL security state for 101 that device. Such states can be: 'disabled', 'sanitize', when 102 a sanitization is currently underway; or those available only 103 for persistent memory: 'locked', 'unlocked' or 'frozen'. This 104 sysfs entry is select/poll capable from userspace to notify 105 upon completion of a sanitize operation. 106 107 108What: /sys/bus/cxl/devices/memX/security/sanitize 109Date: June, 2023 110KernelVersion: v6.5 111Contact: linux-cxl@vger.kernel.org 112Description: 113 (WO) Write a boolean 'true' string value to this attribute to 114 sanitize the device to securely re-purpose or decommission it. 115 This is done by ensuring that all user data and meta-data, 116 whether it resides in persistent capacity, volatile capacity, 117 or the LSA, is made permanently unavailable by whatever means 118 is appropriate for the media type. This functionality requires 119 the device to be disabled, that is, not actively decoding any 120 HPA ranges. This permits avoiding explicit global CPU cache 121 management, relying instead for it to be done when a region 122 transitions between software programmed and hardware committed 123 states. If this file is not present, then there is no hardware 124 support for the operation. 125 126 127What /sys/bus/cxl/devices/memX/security/erase 128Date: June, 2023 129KernelVersion: v6.5 130Contact: linux-cxl@vger.kernel.org 131Description: 132 (WO) Write a boolean 'true' string value to this attribute to 133 secure erase user data by changing the media encryption keys for 134 all user data areas of the device. This functionality requires 135 the device to be disabled, that is, not actively decoding any 136 HPA ranges. This permits avoiding explicit global CPU cache 137 management, relying instead for it to be done when a region 138 transitions between software programmed and hardware committed 139 states. If this file is not present, then there is no hardware 140 support for the operation. 141 142 143What: /sys/bus/cxl/devices/memX/firmware/ 144Date: April, 2023 145KernelVersion: v6.5 146Contact: linux-cxl@vger.kernel.org 147Description: 148 (RW) Firmware uploader mechanism. The different files under 149 this directory can be used to upload and activate new 150 firmware for CXL devices. The interfaces under this are 151 documented in sysfs-class-firmware. 152 153 154What: /sys/bus/cxl/devices/*/devtype 155Date: June, 2021 156KernelVersion: v5.14 157Contact: linux-cxl@vger.kernel.org 158Description: 159 (RO) CXL device objects export the devtype attribute which 160 mirrors the same value communicated in the DEVTYPE environment 161 variable for uevents for devices on the "cxl" bus. 162 163 164What: /sys/bus/cxl/devices/*/modalias 165Date: December, 2021 166KernelVersion: v5.18 167Contact: linux-cxl@vger.kernel.org 168Description: 169 (RO) CXL device objects export the modalias attribute which 170 mirrors the same value communicated in the MODALIAS environment 171 variable for uevents for devices on the "cxl" bus. 172 173 174What: /sys/bus/cxl/devices/portX/uport 175Date: June, 2021 176KernelVersion: v5.14 177Contact: linux-cxl@vger.kernel.org 178Description: 179 (RO) CXL port objects are enumerated from either a platform 180 firmware device (ACPI0017 and ACPI0016) or PCIe switch upstream 181 port with CXL component registers. The 'uport' symlink connects 182 the CXL portX object to the device that published the CXL port 183 capability. 184 185 186What: /sys/bus/cxl/devices/{port,endpoint}X/parent_dport 187Date: January, 2023 188KernelVersion: v6.3 189Contact: linux-cxl@vger.kernel.org 190Description: 191 (RO) CXL port objects are instantiated for each upstream port in 192 a CXL/PCIe switch, and for each endpoint to map the 193 corresponding memory device into the CXL port hierarchy. When a 194 descendant CXL port (switch or endpoint) is enumerated it is 195 useful to know which 'dport' object in the parent CXL port 196 routes to this descendant. The 'parent_dport' symlink points to 197 the device representing the downstream port of a CXL switch that 198 routes to {port,endpoint}X. 199 200 201What: /sys/bus/cxl/devices/portX/dportY 202Date: June, 2021 203KernelVersion: v5.14 204Contact: linux-cxl@vger.kernel.org 205Description: 206 (RO) CXL port objects are enumerated from either a platform 207 firmware device (ACPI0017 and ACPI0016) or PCIe switch upstream 208 port with CXL component registers. The 'dportY' symlink 209 identifies one or more downstream ports that the upstream port 210 may target in its decode of CXL memory resources. The 'Y' 211 integer reflects the hardware port unique-id used in the 212 hardware decoder target list. 213 214 215What: /sys/bus/cxl/devices/portX/decoders_committed 216Date: October, 2023 217KernelVersion: v6.7 218Contact: linux-cxl@vger.kernel.org 219Description: 220 (RO) A memory device is considered active when any of its 221 decoders are in the "committed" state (See CXL 3.0 8.2.4.19.7 222 CXL HDM Decoder n Control Register). Hotplug and destructive 223 operations like "sanitize" are blocked while device is actively 224 decoding a Host Physical Address range. Note that this number 225 may be elevated without any regionX objects active or even 226 enumerated, as this may be due to decoders established by 227 platform firwmare or a previous kernel (kexec). 228 229 230What: /sys/bus/cxl/devices/decoderX.Y 231Date: June, 2021 232KernelVersion: v5.14 233Contact: linux-cxl@vger.kernel.org 234Description: 235 (RO) CXL decoder objects are enumerated from either a platform 236 firmware description, or a CXL HDM decoder register set in a 237 PCIe device (see CXL 2.0 section 8.2.5.12 CXL HDM Decoder 238 Capability Structure). The 'X' in decoderX.Y represents the 239 cxl_port container of this decoder, and 'Y' represents the 240 instance id of a given decoder resource. 241 242 243What: /sys/bus/cxl/devices/decoderX.Y/{start,size} 244Date: June, 2021 245KernelVersion: v5.14 246Contact: linux-cxl@vger.kernel.org 247Description: 248 (RO) The 'start' and 'size' attributes together convey the 249 physical address base and number of bytes mapped in the 250 decoder's decode window. For decoders of devtype 251 "cxl_decoder_root" the address range is fixed. For decoders of 252 devtype "cxl_decoder_switch" the address is bounded by the 253 decode range of the cxl_port ancestor of the decoder's cxl_port, 254 and dynamically updates based on the active memory regions in 255 that address space. 256 257 258What: /sys/bus/cxl/devices/decoderX.Y/locked 259Date: June, 2021 260KernelVersion: v5.14 261Contact: linux-cxl@vger.kernel.org 262Description: 263 (RO) CXL HDM decoders have the capability to lock the 264 configuration until the next device reset. For decoders of 265 devtype "cxl_decoder_root" there is no standard facility to 266 unlock them. For decoders of devtype "cxl_decoder_switch" a 267 secondary bus reset, of the PCIe bridge that provides the bus 268 for this decoders uport, unlocks / resets the decoder. 269 270 271What: /sys/bus/cxl/devices/decoderX.Y/target_list 272Date: June, 2021 273KernelVersion: v5.14 274Contact: linux-cxl@vger.kernel.org 275Description: 276 (RO) Display a comma separated list of the current decoder 277 target configuration. The list is ordered by the current 278 configured interleave order of the decoder's dport instances. 279 Each entry in the list is a dport id. 280 281 282What: /sys/bus/cxl/devices/decoderX.Y/cap_{pmem,ram,type2,type3} 283Date: June, 2021 284KernelVersion: v5.14 285Contact: linux-cxl@vger.kernel.org 286Description: 287 (RO) When a CXL decoder is of devtype "cxl_decoder_root", it 288 represents a fixed memory window identified by platform 289 firmware. A fixed window may only support a subset of memory 290 types. The 'cap_*' attributes indicate whether persistent 291 memory, volatile memory, accelerator memory, and / or expander 292 memory may be mapped behind this decoder's memory window. 293 294 295What: /sys/bus/cxl/devices/decoderX.Y/target_type 296Date: June, 2021 297KernelVersion: v5.14 298Contact: linux-cxl@vger.kernel.org 299Description: 300 (RO) When a CXL decoder is of devtype "cxl_decoder_switch", it 301 can optionally decode either accelerator memory (type-2) or 302 expander memory (type-3). The 'target_type' attribute indicates 303 the current setting which may dynamically change based on what 304 memory regions are activated in this decode hierarchy. 305 306 307What: /sys/bus/cxl/devices/endpointX/CDAT 308Date: July, 2022 309KernelVersion: v6.0 310Contact: linux-cxl@vger.kernel.org 311Description: 312 (RO) If this sysfs entry is not present no DOE mailbox was 313 found to support CDAT data. If it is present and the length of 314 the data is 0 reading the CDAT data failed. Otherwise the CDAT 315 data is reported. 316 317 318What: /sys/bus/cxl/devices/decoderX.Y/mode 319Date: May, 2022 320KernelVersion: v6.0 321Contact: linux-cxl@vger.kernel.org 322Description: 323 (RW) When a CXL decoder is of devtype "cxl_decoder_endpoint" it 324 translates from a host physical address range, to a device local 325 address range. Device-local address ranges are further split 326 into a 'ram' (volatile memory) range and 'pmem' (persistent 327 memory) range. The 'mode' attribute emits one of 'ram', 'pmem', 328 'mixed', or 'none'. The 'mixed' indication is for error cases 329 when a decoder straddles the volatile/persistent partition 330 boundary, and 'none' indicates the decoder is not actively 331 decoding, or no DPA allocation policy has been set. 332 333 'mode' can be written, when the decoder is in the 'disabled' 334 state, with either 'ram' or 'pmem' to set the boundaries for the 335 next allocation. 336 337 338What: /sys/bus/cxl/devices/decoderX.Y/dpa_resource 339Date: May, 2022 340KernelVersion: v6.0 341Contact: linux-cxl@vger.kernel.org 342Description: 343 (RO) When a CXL decoder is of devtype "cxl_decoder_endpoint", 344 and its 'dpa_size' attribute is non-zero, this attribute 345 indicates the device physical address (DPA) base address of the 346 allocation. 347 348 349What: /sys/bus/cxl/devices/decoderX.Y/dpa_size 350Date: May, 2022 351KernelVersion: v6.0 352Contact: linux-cxl@vger.kernel.org 353Description: 354 (RW) When a CXL decoder is of devtype "cxl_decoder_endpoint" it 355 translates from a host physical address range, to a device local 356 address range. The range, base address plus length in bytes, of 357 DPA allocated to this decoder is conveyed in these 2 attributes. 358 Allocations can be mutated as long as the decoder is in the 359 disabled state. A write to 'dpa_size' releases the previous DPA 360 allocation and then attempts to allocate from the free capacity 361 in the device partition referred to by 'decoderX.Y/mode'. 362 Allocate and free requests can only be performed on the highest 363 instance number disabled decoder with non-zero size. I.e. 364 allocations are enforced to occur in increasing 'decoderX.Y/id' 365 order and frees are enforced to occur in decreasing 366 'decoderX.Y/id' order. 367 368 369What: /sys/bus/cxl/devices/decoderX.Y/interleave_ways 370Date: May, 2022 371KernelVersion: v6.0 372Contact: linux-cxl@vger.kernel.org 373Description: 374 (RO) The number of targets across which this decoder's host 375 physical address (HPA) memory range is interleaved. The device 376 maps every Nth block of HPA (of size == 377 'interleave_granularity') to consecutive DPA addresses. The 378 decoder's position in the interleave is determined by the 379 device's (endpoint or switch) switch ancestry. For root 380 decoders their interleave is specified by platform firmware and 381 they only specify a downstream target order for host bridges. 382 383 384What: /sys/bus/cxl/devices/decoderX.Y/interleave_granularity 385Date: May, 2022 386KernelVersion: v6.0 387Contact: linux-cxl@vger.kernel.org 388Description: 389 (RO) The number of consecutive bytes of host physical address 390 space this decoder claims at address N before the decode rotates 391 to the next target in the interleave at address N + 392 interleave_granularity (assuming N is aligned to 393 interleave_granularity). 394 395 396What: /sys/bus/cxl/devices/decoderX.Y/create_{pmem,ram}_region 397Date: May, 2022, January, 2023 398KernelVersion: v6.0 (pmem), v6.3 (ram) 399Contact: linux-cxl@vger.kernel.org 400Description: 401 (RW) Write a string in the form 'regionZ' to start the process 402 of defining a new persistent, or volatile memory region 403 (interleave-set) within the decode range bounded by root decoder 404 'decoderX.Y'. The value written must match the current value 405 returned from reading this attribute. An atomic compare exchange 406 operation is done on write to assign the requested id to a 407 region and allocate the region-id for the next creation attempt. 408 EBUSY is returned if the region name written does not match the 409 current cached value. 410 411 412What: /sys/bus/cxl/devices/decoderX.Y/delete_region 413Date: May, 2022 414KernelVersion: v6.0 415Contact: linux-cxl@vger.kernel.org 416Description: 417 (WO) Write a string in the form 'regionZ' to delete that region, 418 provided it is currently idle / not bound to a driver. 419 420 421What: /sys/bus/cxl/devices/decoderX.Y/qos_class 422Date: May, 2023 423KernelVersion: v6.5 424Contact: linux-cxl@vger.kernel.org 425Description: 426 (RO) For CXL host platforms that support "QoS Telemmetry" this 427 root-decoder-only attribute conveys a platform specific cookie 428 that identifies a QoS performance class for the CXL Window. 429 This class-id can be compared against a similar "qos_class" 430 published for each memory-type that an endpoint supports. While 431 it is not required that endpoints map their local memory-class 432 to a matching platform class, mismatches are not recommended and 433 there are platform specific side-effects that may result. 434 435 436What: /sys/bus/cxl/devices/regionZ/uuid 437Date: May, 2022 438KernelVersion: v6.0 439Contact: linux-cxl@vger.kernel.org 440Description: 441 (RW) Write a unique identifier for the region. This field must 442 be set for persistent regions and it must not conflict with the 443 UUID of another region. For volatile ram regions this 444 attribute is a read-only empty string. 445 446 447What: /sys/bus/cxl/devices/regionZ/interleave_granularity 448Date: May, 2022 449KernelVersion: v6.0 450Contact: linux-cxl@vger.kernel.org 451Description: 452 (RW) Set the number of consecutive bytes each device in the 453 interleave set will claim. The possible interleave granularity 454 values are determined by the CXL spec and the participating 455 devices. 456 457 458What: /sys/bus/cxl/devices/regionZ/interleave_ways 459Date: May, 2022 460KernelVersion: v6.0 461Contact: linux-cxl@vger.kernel.org 462Description: 463 (RW) Configures the number of devices participating in the 464 region is set by writing this value. Each device will provide 465 1/interleave_ways of storage for the region. 466 467 468What: /sys/bus/cxl/devices/regionZ/size 469Date: May, 2022 470KernelVersion: v6.0 471Contact: linux-cxl@vger.kernel.org 472Description: 473 (RW) System physical address space to be consumed by the region. 474 When written trigger the driver to allocate space out of the 475 parent root decoder's address space. When read the size of the 476 address space is reported and should match the span of the 477 region's resource attribute. Size shall be set after the 478 interleave configuration parameters. Once set it cannot be 479 changed, only freed by writing 0. The kernel makes no guarantees 480 that data is maintained over an address space freeing event, and 481 there is no guarantee that a free followed by an allocate 482 results in the same address being allocated. 483 484 485What: /sys/bus/cxl/devices/regionZ/mode 486Date: January, 2023 487KernelVersion: v6.3 488Contact: linux-cxl@vger.kernel.org 489Description: 490 (RO) The mode of a region is established at region creation time 491 and dictates the mode of the endpoint decoder that comprise the 492 region. For more details on the possible modes see 493 /sys/bus/cxl/devices/decoderX.Y/mode 494 495 496What: /sys/bus/cxl/devices/regionZ/resource 497Date: May, 2022 498KernelVersion: v6.0 499Contact: linux-cxl@vger.kernel.org 500Description: 501 (RO) A region is a contiguous partition of a CXL root decoder 502 address space. Region capacity is allocated by writing to the 503 size attribute, the resulting physical address space determined 504 by the driver is reflected here. It is therefore not useful to 505 read this before writing a value to the size attribute. 506 507 508What: /sys/bus/cxl/devices/regionZ/target[0..N] 509Date: May, 2022 510KernelVersion: v6.0 511Contact: linux-cxl@vger.kernel.org 512Description: 513 (RW) Write an endpoint decoder object name to 'targetX' where X 514 is the intended position of the endpoint device in the region 515 interleave and N is the 'interleave_ways' setting for the 516 region. ENXIO is returned if the write results in an impossible 517 to map decode scenario, like the endpoint is unreachable at that 518 position relative to the root decoder interleave. EBUSY is 519 returned if the position in the region is already occupied, or 520 if the region is not in a state to accept interleave 521 configuration changes. EINVAL is returned if the object name is 522 not an endpoint decoder. Once all positions have been 523 successfully written a final validation for decode conflicts is 524 performed before activating the region. 525 526 527What: /sys/bus/cxl/devices/regionZ/commit 528Date: May, 2022 529KernelVersion: v6.0 530Contact: linux-cxl@vger.kernel.org 531Description: 532 (RW) Write a boolean 'true' string value to this attribute to 533 trigger the region to transition from the software programmed 534 state to the actively decoding in hardware state. The commit 535 operation in addition to validating that the region is in proper 536 configured state, validates that the decoders are being 537 committed in spec mandated order (last committed decoder id + 538 1), and checks that the hardware accepts the commit request. 539 Reading this value indicates whether the region is committed or 540 not. 541 542 543What: /sys/bus/cxl/devices/memX/trigger_poison_list 544Date: April, 2023 545KernelVersion: v6.4 546Contact: linux-cxl@vger.kernel.org 547Description: 548 (WO) When a boolean 'true' is written to this attribute the 549 memdev driver retrieves the poison list from the device. The 550 list consists of addresses that are poisoned, or would result 551 in poison if accessed, and the source of the poison. This 552 attribute is only visible for devices supporting the 553 capability. The retrieved errors are logged as kernel 554 events when cxl_poison event tracing is enabled. 555 556 557What: /sys/bus/cxl/devices/regionZ/accessY/read_bandwidth 558 /sys/bus/cxl/devices/regionZ/accessY/write_banwidth 559Date: Jan, 2024 560KernelVersion: v6.9 561Contact: linux-cxl@vger.kernel.org 562Description: 563 (RO) The aggregated read or write bandwidth of the region. The 564 number is the accumulated read or write bandwidth of all CXL memory 565 devices that contributes to the region in MB/s. It is 566 identical data that should appear in 567 /sys/devices/system/node/nodeX/accessY/initiators/read_bandwidth or 568 /sys/devices/system/node/nodeX/accessY/initiators/write_bandwidth. 569 See Documentation/ABI/stable/sysfs-devices-node. access0 provides 570 the number to the closest initiator and access1 provides the 571 number to the closest CPU. 572 573 574What: /sys/bus/cxl/devices/regionZ/accessY/read_latency 575 /sys/bus/cxl/devices/regionZ/accessY/write_latency 576Date: Jan, 2024 577KernelVersion: v6.9 578Contact: linux-cxl@vger.kernel.org 579Description: 580 (RO) The read or write latency of the region. The number is 581 the worst read or write latency of all CXL memory devices that 582 contributes to the region in nanoseconds. It is identical data 583 that should appear in 584 /sys/devices/system/node/nodeX/accessY/initiators/read_latency or 585 /sys/devices/system/node/nodeX/accessY/initiators/write_latency. 586 See Documentation/ABI/stable/sysfs-devices-node. access0 provides 587 the number to the closest initiator and access1 provides the 588 number to the closest CPU. 589