1 .. SPDX-License-Identifier: GPL-2.0
2
3 ==================================
4 NVDIMM Runtime Firmware Activation
5 ==================================
6
7 Some persistent memory devices run a firmware
8 "DIMM" to perform tasks like media management,
9 and health monitoring. The process of updating
10 involves a reboot because it has implications
11 transactions. However, reboots are disruptive
12 persistent memory platform implementation, des
13 DSM specification [1], has added support for a
14 runtime.
15
16 A native sysfs interface is implemented in lib
17 to advertise and control their local runtime f
18 capability.
19
20 The libnvdimm bus object, ndbusX, implements a
21 attribute that shows the state of the firmware
22 'armed', 'overflow', and 'busy'.
23
24 - idle:
25 No devices are set / armed to activate firmw
26
27 - armed:
28 At least one device is armed
29
30 - busy:
31 In the busy state armed devices are in the p
32 back to idle and completing an activation cy
33
34 - overflow:
35 If the platform has a concept of incremental
36 the activation it could be the case that too
37 activation. In that scenario the potential f
38 timeout is indicated by the 'overflow' state
39
40 The 'ndbusX/firmware/activate' property can be
41 either 'live', or 'quiesce'. A value of 'quies
42 run firmware activation from within the equiva
43 'freeze' state where drivers and applications
44 modifications of system memory. A value of 'li
45 firmware activation without this hibernation c
46 'ndbusX/firmware/activate' property will be el
47 firmware activation capability is detected.
48
49 Another property 'ndbusX/firmware/capability'
50 'live' or 'quiesce', where 'live' indicates th
51 does not require or inflict any quiesce period
52 firmware. A capability value of 'quiesce' indi
53 expect and injects a quiet period for the memo
54 may still be written to 'ndbusX/firmware/activ
55 assume the risk of racing firmware update with
56 application activity. The 'ndbusX/firmware/cap
57 elided completely if no firmware activation ca
58
59 The libnvdimm memory-device / DIMM object, nme
60 'nmemX/firmware/activate' and 'nmemX/firmware/
61 communicate the per-device firmware activation
62 'ndbusX/firmware/activate' attribute, the 'nme
63 attribute indicates 'idle', 'armed', or 'busy'
64 from 'armed' to 'idle' when the system is prep
65 firmware staged + state set to armed, and 'ndb
66 triggered. After that activation event the nme
67 attribute reflects the state of the last activ
68
69 - none:
70 No runtime activation triggered since the la
71
72 - success:
73 The last runtime activation completed succes
74
75 - fail:
76 The last runtime activation failed for devic
77
78 - not_staged:
79 The last runtime activation failed due to a
80 firmware image not being staged.
81
82 - need_reset:
83 Runtime firmware activation failed, but the
84 activated via the legacy method of power-cyc
85
86 [1]: https://docs.pmem.io/persistent-memory/
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