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