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33 .Nd Intel integrated Memory Controller (iMC) SMBus controller driver
39 Alternatively, to load the driver as a module at boot time, place the following
42 .Bd -literal -offset indent
50 support for the SMBus controller functionality in the integrated Memory
51 Controllers (iMCs) embedded in Intel Sandybridge-Xeon, Ivybridge-Xeon,
52 Haswell-Xeon, and Broadwell-Xeon CPUs.
53 Each CPU implements one or more iMCs, depending on the number of cores;
54 each iMC implements two SMBus controllers (iMC-SMBs).
55 The iMC-SMBs are used by the iMCs to read configuration information from the
57 They may also be used, by motherboard firmware or a BMC, to monitor the
58 temperature of the DIMMs.
62 general-purpose SMBus controllers.
63 By their nature, they are only ever attached to DIMMs, so they implement only
64 the SMBus operations need for communicating with DIMMs.
67 .Bl -dash -offset indent -compact
78 A more detailed discussion of the hardware and driver architecture can be found
80 .Pa sys/dev/imcsmb/imcsmb_pci.c .
82 As mentioned above, firmware might use the iMC-SMBs to read DIMM temperatures.
83 The public iMC documentation does not describe any sort of coordination
84 mechanism to prevent requests from different sources -- such as the motherboard
85 firmware, a BMC, or the operating system -- from interfering with each other.
88 Therefore, it is highly recommended that developers contact the motherboard
89 vendor for any board-specific instructions on how to disable and re-enable DIMM
90 temperature monitoring.
93 DIMM temperature monitoring should be disabled before returning from
94 .Fn imcsmb_pci_request_bus ,
95 and re-enabled before returning from
96 .Fn imcsmb_pci_release_bus .
97 The driver includes comments to that effect at the appropriate locations.
98 The driver has been tested and shown to work, with only that type of
99 modification, on certain motherboards from Intel.
101 Unfortunately, those modifications were based on material covered under a
102 non-disclosure agreement, and therefore are not included in this driver.
104 The driver has also been tested and shown to work as-is on various motherboards
109 driver will connect to the
113 However, since the IMC-SMBs are not general-purpose SMBus controllers, using
117 devices is not supported.
124 driver first appeared in
129 driver was originally written for Panasas by
131 It was substantially refactored, and this manual page was written, by
132 .An Ravi Pokala Aq Mt rpokala@freebsd.org