Penguin Computing Relion 1900e, Technical Manual

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Relion 1900e/2900e Manual
Revision 1.0 82
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The ME uses the SMLink1 on the SSB in multi-master mode bus for communication with PMBus*
devices in the power supplies for support of various NM-related features. This bus is shared with the
BMC, which polls these PMBus* power supplies for sensor monitoring purposes (for example, power
supply status, input power, and so on). This bus runs at
100 KHz.
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The Management Engine has access to the “Host SMBus*”.
8.4 PECI 3.0
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The BMC owns the PECI bus for all Intel server implementations and acts as a proxy for the ME when
necessary.
8.5 NM “Discovery” OEM SDR
A NM “discovery” OEM SDR must be loaded into the BMC’s SDR repository if and only if the NM feature is
supported on that product. This OEM SDR is used by management software to detect if NM is supported and
to understand how to communicate with it.
Since PMBus* compliant power supplies are required in order to support NM, the system should be probed
when the SDRs are loaded into the BMC’s SDR repository in order to determine whether or not the installed
power supplies do in fact support PMBus*. If the installed power supplies are not PMBus* compliant then the
NM “discovery” OEM SDR should not be loaded.
Please refer to the Intel® Intelligent Power Node Manager 2.0 External Architecture Specification using IPMI
for details of this interface.
8.6 SmaRT/CLST
The power supply optimization provided by SmaRT/CLST relies on a platform HW capability as well as ME
FW support. When a PMBus*-compliant power supply detects insufficient input voltage, an overcurrent
condition, or an over-temperature condition, it will assert the SMBAlert# signal on the power supply SMBus*
(such as, the PMBus*). Through the use of external gates, this results in a momentary assertion of the
PROCHOT# and MEMHOT# signals to the processors, thereby throttling the processors and memory. The ME
FW also sees the SMBAlert# assertion, queries the power supplies to determine the condition causing the
assertion, and applies an algorithm to either release or prolong the throttling, based on the situation.
System power control modes include:
1. SmaRT: Low AC input voltage event; results in a one-time momentary throttle for each event to the
maximum throttle state
2. Electrical Protection CLST: High output energy event; results in a throttling hiccup mode with fixed
maximum throttle time and a fix throttle release ramp time.
3. Thermal Protection CLST: High power supply thermal event; results in a throttling hiccup mode with
fixed maximum throttle time and a fix throttle release ramp time.
When the SMBAlert# signal is asserted, the fans will be gated by HW for a short period (~100ms) to reduce
overall power consumption. It is expected that the interruption to the fans will be of short enough duration
to avoid false lower threshold crossings for the fan tach sensors; however, this may need to be
comprehended by the fan monitoring FW if it does have this side-effect.
ME FW will log an event into the SEL to indicate when the system has been throttled by the SmaRT/CLST
power management feature. This is dependent on ME FW support for this sensor. Please reference the ME
FW EPS for SEL log details.