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<table class="head">
<tr>
<td class="head-ltitle">IMCSMB(4)</td>
<td class="head-vol">Device Drivers Manual</td>
<td class="head-rtitle">IMCSMB(4)</td>
</tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">imcsmb</code> — <span class="Nd">Intel
integrated Memory Controller (iMC) SMBus controller driver</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="Cd">device pci</code>
<br/>
<code class="Cd">device smbus</code>
<br/>
<code class="Cd">device imcsmb</code></p>
<p class="Pp">Alternatively, to load the driver as a module at boot time, place
the following line in <a class="Xr">loader.conf(5)</a>:</p>
<div class="Bd Pp Bd-indent Li">
<pre>imcsmb_load="YES"</pre>
</div>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">imcsmb</code> driver provides
<a class="Xr">smbus(4)</a> 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.</p>
<p class="Pp" id="not">The iMC-SMBs are
<a class="permalink" href="#not"><b class="Sy">not</b></a> general-purpose
SMBus controllers. By their nature, they are only ever attached to DIMMs, so
they implement only the SMBus operations need for communicating with DIMMs.
Specifically:</p>
<p class="Pp"></p>
<ul class="Bl-dash Bd-indent Bl-compact">
<li>READB</li>
<li>READW</li>
<li>WRITEB</li>
<li>WRITEW</li>
</ul>
<p class="Pp">A more detailed discussion of the hardware and driver architecture
can be found at the top of
<span class="Pa">sys/dev/imcsmb/imcsmb_pci.c</span>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="WARNINGS"><a class="permalink" href="#WARNINGS">WARNINGS</a></h1>
<p class="Pp">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.</p>
<p class="Pp"></p>
<div class="Bf Sy">Therefore, it is highly recommended that developers contact
the motherboard vendor for any board-specific instructions on how to disable
and re-enable DIMM temperature monitoring.</div>
<p class="Pp" id="imcsmb_pci_request_bus">DIMM temperature monitoring should be
disabled before returning from
<a class="permalink" href="#imcsmb_pci_request_bus"><code class="Fn">imcsmb_pci_request_bus</code></a>(),
and re-enabled before returning from
<a class="permalink" href="#imcsmb_pci_release_bus"><code class="Fn" id="imcsmb_pci_release_bus">imcsmb_pci_release_bus</code></a>().
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.</p>
<p class="Pp">The <a class="Xr">smb(4)</a> driver will connect to the
<a class="Xr">smbus(4)</a> instances created by
<code class="Nm">imcsmb</code>. However, since the IMC-SMBs are not
general-purpose SMBus controllers, using <a class="Xr">smbmsg(8)</a> with
those <a class="Xr">smb(4)</a> devices is not supported.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
ALSO</a></h1>
<p class="Pp"><a class="Xr">jedec_dimm(4)</a>, <a class="Xr">smbus(4)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The <code class="Nm">imcsmb</code> driver first appeared in
<span class="Ux">FreeBSD 12.0</span>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
<p class="Pp">The <code class="Nm">imcsmb</code> driver was originally written
for Panasas by <span class="An">Joe Kloss</span>. It was substantially
refactored, and this manual page was written, by
<br/>
<span class="An">Ravi Pokala</span>
<<a class="Mt" href="mailto:rpokala@freebsd.org">rpokala@freebsd.org</a>></p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">March 2, 2018</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
