IMCSMB(4) | Device Drivers Manual (x86) | IMCSMB(4) |
imcsmb
— Intel
integrated Memory Controller (iMC) SMBus controller driver
imc* at pci? dev ? func ?
imcsmb* at imc?
iic* at i2cbus?
Alternatively, to load the driver as a module at boot time, place the following line in boot.cfg(5):
load=imcsmb
or add the following line to your /etc/modules file:
imcsmb
The imcsmb
driver provides
iic(4) support for the SMBus
controller functionality in the integrated Memory Controllers (iMCs)
embedded in Intel Sandybridge-Xeon, Ivybridge-Xeon, Haswell-Xeon, and
Broadwell-Xeon CPUs. Each CPU implements one or more iMCs, depending on the
number of cores; each iMC implements two SMBus controllers (iMC-SMBs). The
iMC-SMBs are used by the iMCs to read configuration information from the
DIMMs during POST. They may also be used, by motherboard firmware or a BMC,
to monitor the temperature of the DIMMs.
The iMC-SMBs are not general-purpose SMBus controllers. By their nature, they are only ever attached to DIMMs, so they implement only the SMBus operations needed for communicating with DIMMs. Specifically:
A more detailed discussion of the hardware and driver architecture can be found at the top of sys/dev/imcsmb/imc.c.
As mentioned above, firmware might use the iMC-SMBs to read DIMM temperatures. The public iMC documentation does not describe any sort of coordination mechanism to prevent requests from different sources — such as the motherboard firmware, a BMC, or the operating system — from interfering with each other.
DIMM temperature monitoring should be
disabled before returning from
imcsmb_pci_request_bus
(),
and re-enabled before returning from
imcsmb_pci_release_bus
().
The driver includes comments to that effect at the appropriate locations.
The driver has been tested and shown to work, with only that type of
modification, on certain motherboards from Intel. (Unfortunately, those
modifications were based on material covered under a non-disclosure
agreement, and therefore are not included in this driver.) The driver has
also been tested and shown to work as-is on various motherboards from
SuperMicro and ASUS.
Because of the above, the imcsmb
driver is
not included in the default GENERIC
kernel. In order
to use the imcsmb
driver, you must compile a custom
kernel, or load the driver using
modload(8).
The iic(4) driver
will connect to the i2cbus instances created by
imcsmb
.
The imcsmb
driver first appeared in
FreeBSD 12.0. It was later ported to
NetBSD 9.0.
The imcsmb
driver was originally written
for Panasas by Joe Kloss. It was substantially
refactored, and this manual page was written, by Ravi
Pokala
<rpokala@freebsd.org>.
It was adapted to NetBSD by Paul
Goyette
<pgoyette@NetBSD.org>.
April 16, 2020 | NetBSD 10.99 |