Kontron AM4320 - Manual (Page 19)

7 AM4320
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2.4 Hardware Management Overview
The AMC Carrier communicates with the Module Management Controller (MMC) using the IPMB_L channel.
The memory subsystem of the MMC consists of an integrated flash memory to hold the MMC operation code
and integrated RAM for data. The field replacement unit (FRU) inventory information is stored in the
nonvolatile memory on an EEPROM and connected via a local I2C interface to the MMC microcontroller. It is
possible to store up to 4 KBytes within the FRU inventory information. Event generation over IPMB-L bus to
reach the AMC Carrier that forward it to the ShMc ensure that 'post-mortem' logging information is available
even if the power of the AMC is disabled.
The onboard DC voltages and temperature are monitored by the MMC microcontroller device. The MMC will
send an event to the Carrier if any of the thresholds are exceeded.
To increase the reliability of the AM4320 management subsystem, an external watchdog supervisor for the
MMC is implemented. The MMC must strobe the external watchdog at two-second intervals to indicate
continuity of operation of the board's management subsystem. If the MMC ceases to strobe the watchdog
supervisor, the watchdog isolates the MMC from the IPMBs and resets the MMC. The watchdog supervisor
does not reset the payload power the restart of the MMC will not affect the payload and will restore the
previous Module Hot Swap state. The watchdog timeout expires after six seconds if strobes are not received.
The external watchdog supervisor is not configurable and must not be confused with the IPMI v1.5 watchdog
timer commands.
A boot block located on the microcontroller is responsible for managinge the MMC's fail safe firmware
upgrade process. It can sotre two Firmware copies located on an external flash memory. If a failure occurs
during firmware upgrade, the Boot Block will automatically rollback to the redundant MMC firmware image.
2.4.1 Sensor Data Record (SDR)
Every sensor on the baseboard is associated with a Sensor Data Record (SDR). Sensor Data Records contain
information about the sensors identification such as sensor type, sensor name, sensor unit. SDR also contain
the configuration of a specific sensor such as threshold/hysteresis and event generation capabilities that
specify sensor behavior. Some fields of the sensor SDR are configurable through IPMI v1.5 commands and
are set to built-in initial values. Finally one field which is the sensor owner must reflect the module addresses
that allow the AMC Carrier to identify the owner of the SDR when it is scanned by the module management
controller and merged within the AMC Carrier Device SDR repository.
From an IPMI perspective, the AM4320 management controller is set up as a satellite management controller
(SMC). It supports sensor devices, and uses the IPMI static sensor population feature of IPMI v1.5 to merge
the hot swapped AMC sensor with the carrier board sensors population. The AMC Carrier is informed of AMC
insertion events through the AMC Module Hot Swap sensor and a radial presence line on the AMC connector.
All SDRs can be queried using Device SDR commands to the firmware. Module sensors that have been
implemented are listed the next section.